Veget Hist Archaeobot (2003) 12:187–204 DOI 10.1007/s00334-003-0016-5 ORIGINAL ARTICLE Barbara Zach · Marlies Klee Four thousand years of plant exploitation in the Chad Basin of NE Nigeria II: discussion on the morphology of caryopses of domesticated Pennisetum and complete catalogue of the fruits and seeds of Kursakata Received: 22 August 2002 / Accepted: 27 July 2003 / Published online: 23 September 2003
Springer-Verlag 2003 Abstract This paper continues the presentation of archaeobotanical remains from Kursakata, northeast Nigeria, with a more detailed discussion on Pennisetum (part 1) and the catalogue of the fruits and seeds (part 2). The settlement mound of Kursakata was introduced in an earlier publication (Klee et al. 2000). An important topic is the morphological criteria for separating domesticated pearl millet grains from those of wild species. Very small naked grains of Pennisetum glaucum (L.) R. Br. (pearl millet) were noticeable among the rich archaeobotanical remains in deposits at least from 800 cal B.C. and younger. The question is raised whether these grains really derived from domesticated Pennisetum glaucum or from wild Pennisetum species. The club-shaped outline and the thickness to breadth (T/B) index which correspond to modern domesticated caryopses are the main features which led to the conclusion that they belong to a domesticated type. The catalogue comprises all identified taxa from this archaeological site. As descriptions are rarely available for most of these West African species, it gives their morphological portraits which are particularly outstanding in African archaeobotany. Introduction The Nigerian Chad Basin is one of the study areas of a Joint Research Project of the Universities of Frankfurt am Main, Germany and Maiduguri, Nigeria. In 1994, excavations were carried out at the settlement mound of Kursakata, located near Lake Chad in northeast Nigeria, by Detlef Gronenborn (Gronenborn 1998), (Fig. 1). As presented in the first paper (Klee et al. 2000), the Late Stone Age and Iron Age sequence at Kursakata is dated from about 1000 cal. b.c. to cal. a.d. 100. More than 6,000 mostly carbonised seeds or fruits of 54 taxa were counted, of which 70% were identified (Table 1). These were domesticated Pennisetum glaucum (pearl millet), wild rice and Paniceae, tree fruits, other useful plants and some wild plants. Most of the wild plants were probably collected for food. Pearl millet is the only cultigen which was found. Imprints of its remains Keywords West Africa · Morphology of seeds · Domesticated Pennisetum · Late Stone Age · Early Iron Age B. Zach ()) Labor fr Archobotanik Zach Bernbeuren, Team Archobotanik c/o Universitt Hohenheim, Weidachring 4, 86975 Bernbeuren, Germany e-mail: Zach@uni-hohenheim.de M. Klee Seminar fr Ur- und Frhgeschichte, Abteilung Archobiologie, Archobotanik, Universitt Basel, Spalenring 145, 4055, Basel, Switzerland Fig. 1 The study area: northeast Nigeria, the Chad Basin southwest of Lake Chad 188 Table 1 Kursakata, northern Nigeria. Late Stone Age and Early Iron Age carbonised seeds and fruits. Complete list of seeds and fruits with sum of specimens. Species in alphabetical order, nomenclature after Burkill (1985–1997) Species Family total Acacia nilotica vel Parkia biglobosa cf. Aeschynomene sp. Brachiaria sp. cf. Bulbostylis congolensis cf. Carex sp. Caryophyllaceae/Molluginaceae indet. Celtis integrifolia Celtis integrifolia (uncharred) Cenchrus biflorus Commelina cf. benghalensis cf. Cyperus (tuber) Cyperaceae indet. Dactyloctenium aegyptium Digitaria cf. ciliaris Digitaria sp. Echinochloa colona/E. pyramidalis Echinochloa sp. Eleusine cf. coracana Eleusine indica Eragrostis cf. pilosa Fimbristylis hispidula vel Bulbostylis congolensis Fimbristylis hisp. vel Bulbostylis congol. (uncharred) cf. Fimbristylis hisp. vel Bulbostylis congol. (inner fruit) Gramineae indet. Gramineae indet., culms Gramineae indet., culms (uncharred) Gynandropsis gynandra Heliotropium cf. subulatum Heliotropium sp. Hibiscus esculentus Hibiscus trionum cf. Indigofera sp. cf. Malvaceae indet. Mimosaceae/Caesalpinaceae indet. Oryza sp. Oryza (uncharred) Paniceae indet., type 1 Paniceae indet., type 2 Papilionaceae indet., type 1 Papilionaceae indet., type 2 Papilionaceae indet., type 3 Papilionaceae indet., type 4 Papilionaceae indet., type 5 Papilionaceae indet. (fragments) Pennisetum glaucum Pennisetum glaucum (involucres) Pennisetum sp. ( wild) Portulaca oleracea Sorghum sp. Trianthema pentandra Trifoliae-type Vitex simplicifolia Vitex sp. (pieces of epidermis) Vitex sp. (fragments) Ziziphus mauritania vel spina-christi KUR 1 type KUR 2 type KUR 3 type KUR 4 type KUR 5 type KUR 6 type Indeterminata Indeterminata (uncharred) Sum Mimosaceae Papilionaceae Gramineae Cyperaceae Cyperaceae Caryophyllaceae/Molluginaceae Ulmaceae Ulmaceae Gramineae Commelinaceae Cyperaceae Cyperaceae Gramineae Gramineae Gramineae Gramineae Gramineae Gramineae Gramineae Gramineae Cyperaceae Cyperaceae Cyperaceae Gramineae Gramineae Gramineae Capparaceae Boraginaceae Boraginaceae Malvaceae Malvaceae Papilionaceae Malvaceae Papilionaceae Gramineae Gramineae Gramineae Gramineae Papilionaceae Papilionaceae Papilionaceae Papilionaceae Papilionaceae Papilionaceae Gramineae Gramineae Gramineae Portulacaceae Gramineae Ficoidaceae Papilionaceae Verbenaceae Verbenaceae Verbenaceae Rhamnaceae Indeterminata Indeterminata Indeterminata Indeterminata Indeterminata Indeterminata Indeterminata Indeterminata 1 2 24 1 1 1 3 294 1 8 1 2 9 2 40 26 5 1 12 33 30 10 1 96 731 13 1 3 7 17 1 1 2 8 407 3 462 58 1 1 6 2 1 23 823 2 59 1 19 8 11 10 99 964 35 644 10 19 10 512 1 655 5 6,239 189 (spikelets, bristles, involucres and grains) in potsherds will be discussed together with those in the pottery of the “Gajiganna Culture” complex in a third part following in a later volume (Klee et al., in preparation). An introduction to the site of Kursakata and the archaeological background, ecological considerations and the presentation of the results of the charcoal analyses were subject of the first part (Klee et al. 2000). Palaeoenvironment and the economy of Kursakata were discussed for the Late Stone Age and the Iron Age. Both cultivated pearl millet and collected wild grasses were found to play an important role together in the economies which developed in the African savannah regions. This feature can be observed not only in the Late Stone Age but also in all following layers up to modern times. This paper first discusses Pennisetum glaucum (L.) R. Br. (pearl millet) in a probably early domesticated stage. Secondly, it aims to furnish descriptions for the complete seed assemblage of the 1,000 year old sequence dating into the first millennium b.c. Wasylikowa’s descriptions of archaeobotanical remains of Nabta Playa, Egypt (Wasylikowa 1997) were the first detailed descriptions on taxa of the African flora north of the equator. They were taken as reference for our identifications, as some of the taxa which occurred in Nabta Playa were also present in Kursakata. segregated by Brunken into three subspecies: the domesticated ssp. americanum, the wild ssp. monodii (Maire) Brunken and the weedy ssp. stenostachyum (Klotzsch) Brunken. Pennisetum americanum ssp. americanum (pearl millet) is interfertile with its wild and weedy races, but hybrids with P. purpureum are sterile (Brunken 1977). The wild subspecies P. americanum ssp. monodii includes P. fallax (Fig. & De Not) Stapf & Hubbard and P. violaceum (Lam.) L. Rich. and represents the wild progenitor of cultivated pearl millet (Brunken 1977, Brunken et al. 1977). The weedy subspecies, the so-called shibras, are the result of hybridisation between wild and domesticated pearl millets. Therefore shibras show an intermediate morphology. Both pearl millet and shibras depend in their reproduction upon cultivation processes and therefore upon humans. P. americanum (L.) Leeke is a synonym for P. glaucum (L.) R. Br. (Burkill 1985– 1997). In this paper the nomenclature for P. follows Burkill, with the exception of this chapter where Brunken’s (1977 and Brunken et al.1977) taxonomy is employed. He uses P. americanum ssp. americanum without noting down an author for the domesticated pearl millet. The reference material applied for identification of P. spp. (see part 2) used inconsistent nomenclatures. Some of the wild P. species in the following catalogue are not listed in Brunken’s classification. Part 1: taxonomy, morphology, early evidence and cultivation of Pennisetum glaucum (L.) R. Br. Early evidence of pearl millet Taxonomy Several authors have described the taxonomy of the genus Pennisetum in different, non-congruent ways. Some authors divide Pennisetum sect. Pennisetum into many different species, while Brunken (1977) gives the most compact taxonomy. He distinguishes between P. purpureum Schumach. which includes perennial stoloniferous plants and P. americanum (L.) Leeke, a group of annual, tillering grasses. P. americanum (L.) Leeke is Archaeobotanical evidence for Pennisetum ssp. and information on its early domestication history are still very scarce. The available information comes from a broad region extending from the margins of the Sahara to the dry woodland savannah. Sites with earliest evidence of domesticated pearl millet are located in southern Mauretania and northern Ghana (around 1800–1700 b.c.). They do not only represent the northernmost but also the southernmost known places. The easternmost early remains, which are 500 years younger, are from the Lake Table 2 Compilation of the oldest known archaeobotanical remains of Pennisetum glaucum published in the literature State Location Uncal. b.p. Cal. b.c. Preservation Author(s) SE Mauritania Dhars Tichitt and Oualata, Sahara 3500€100 1936–1683 Imprints in potsherds N Ghana Mali 3460€200 Probably 3310€110 2931€32 1740 Carbonised remains Imprints in potsherds N Burkina Faso NE Nigeria Birimi, dry woodland savanna Karkarichinkat, Lower Tilemsi Valley, Sahara Oursi, Sahel Gajiganna, Lake Chad Basin Jacques-Felix (1971); Amblard and Perns (1989); Amblard (1996) D’Andrea et al. (2001) Smith (1974); Smith (1975) 1257–1053 1260–1061 Carbonised remains Imprints in potsherds N Burkina Faso NE Nigeria Tin-Akof, Sahel Kursakata, Lake Chad Basin 2840€49 2615€36 1034–916 808–792 Carbonised remains Carbonised remains Neumann (1999) Wendt (1997); Klee and Zach (1999) Neumann (1999) Neumann et al. (1996); Klee and Zach (1999); Klee et al. (2000) 190 Table 3 Measurements and T/B (thickness/breadth) indices of domesticated, intermediate shibras, and wild Pennisetum glaucum caryopses from carbonised remains from Birimi, Arondo, and Kursakata, published values in Brunken (1977; Table 1, “measurements and compression ratio”) and measurements from the reference collections in Frankfurt and Berlin. The measurements give the values in mm: average (maximum–minimum) or the parts which are published. The T/B ratios are calculated by the authors, published values in italics Taxa Origin Age No. of specimens Length (mm) Breadth (mm) Thickness (mm) T/B Domesticated pearl millet Birimi, N Ghana (after D’Andrea et al. 2001) Kursakata, Nigeria Arondo, Senegal (after Gallagher 1999) Frankfurt ref. coll. After Brunken (1977) After Brunken (1977), No. 1673a After Brunken (1977) Frankfurt /Berlin ref. coll. 1740 cal. b.c. 376 b 0.9 (1.9–0.6) 0.8 (1.7–0.6) 88 0.6–2 1.28 0.6–1.1 1.15 86 90 1.2–2.5 1.6–3.2 2.4 1–2.4 1.2–2.5 2.1 90 88 Shibra Shibra or wild Pennisetum Wild Pennisetum Kursakata, Nigeria After Brunken (1977) After Brunken (1977), No. 662a After Brunken (1977), No. 1659a 800 cal. b.c. L: 8 B, T: 29 1.3–2.4 400–1000 cal. a.d. 1.86 Extant Extant Extant Extant Extant 30 16 12 2–5 2–5.5 3.8 2–4.5 1–2.2 1–2 1.55 (2.8–0.8) 0.69 (1.0–0.5) 0.48 (0.8–0.3) 68 800 cal. B.C. Extant Extant - 1.28 1.9–0.8) 2–3 2.8 0.76 (1.0–0.5) 0.76 (1.0–0.5) 64 1–1.5 0.6–1 1.4 1.0 71 Extant - 3.0 1.4 0.9 64 a Accession b No. after Brunken (1977), Table 1, domesticated pearl millet p. 169, shibra p. 170, wild Pennisetum spp. p. 173 Scutellum is missing Chad Basin (Gajiganna). The following table (Table 2) gives a list of the published results. Typical features of domesticated caryopses Features of caryopses of domesticated Pennisetum glaucum (L.) R. Br. were acquired from descriptions given by Brunken et al. (1977a) and from the available reference material. Values of length, breadth and thickness are comparable (Table 3 and catalogue). Although seed size varies in a single ear and varies highly in different taxa of domesticates (Harlan 1992), domesticated pearl millet is undoubtedly distinguishable from the wild Pennisetum ssp. grains by the typical club-shaped to spherical outline (see Part 2, Catalogue). Caryopses of Pennisetum sp. from Kursakata The archaeobotanical remains of charred domesticated Pennisetum are restricted to naked grains, apart from two involucres. Club-shaped forms could be easily separated from elliptical ones, the latter similar in size and outline to wild types in the modern reference material (Fig. 11, nos. 1 and 2). Although the old club-shaped specimens looked very much like modern domesticated grains, they were very small compared with them. Only a few barely reached the size (length with embryo tip and without, thickness and breadth) of modern domesticated grains, while the greater number fell into the range of the wild specimens (Fig. 2, Table 3). It was not often possible to Fig. 2 Measurements of wild (W) and domesticated (D), carbonised Pennisetum spp. caryopses from Kursakata (o for old), Nigeria (Late Stone Age and Iron Age) and modern (e for extant) references (Frankfurt and Berlin). Thickness vs. breadth dimensions measure the length because only eight caryopses showed an entire scutellum. The values of those eight fall into the range of modern wild specimens (Fig. 3). The index of thickness vs. breadth (T/B) is a feature found to be highly reliable. The T/B index of the caryopses of domesticated P. glaucum from Kursakata corresponded to modern specimens as well as those of the wild P. ssp., and between the values of the domesticated and the wild taxa there is a significant difference (Table 4, Fig. 2). 191 highest increase can be recorded in the transition to the modern grains. Discussion Fig. 3 Measurements of wild (W) and domesticated (D) carbonised Pennisetum spp. caryopses from Kursakata (o for old), Nigeria (Late Stone Age and Iron Age) and modern (e for extant) references (Frankfurt and Berlin). Length vs. breadth dimensions Table 4 Comparison of descriptions of achenes of Fimbristylis spp. and Bulbostylis spp. and synonyms given in various sources concerning the presence of transverse undulations: FWTA, Berhaut (1988) and the Frankfurt reference collection (Ffm collection, nomenclature after FWTA) species FWTA Berhaut Ffm collection Fimbristylis bisumbellata F. cioniana (syn: Bulbostylis cioniana) F. debilis F. dichotoma F. hispidula F. obtusifolia (syn: F. cymosa) F. pilosa F. striolata F. tisserantii B. abortiva B. barbara B. coelotricha B. congolensis B. densa B. guineensis B. lanifera B. pusilla B. scabricaulis Yes Yes Yes Yes - No Yes Yes No No Yes Yes No No No Yes No Yes No No No Yes Yes No No Yes No No No No No Yes No No No Yes No No No No No Yes Yes No No Comparison of measurements of caryopses of pearl millet from Kursakata with other published archaeological sites (dating and location of the sites see Tables 2 and 3) As in Iron Age Kursakata, the grains of pearl millet from Late Stone Age Birimi (northern Ghana), and the medieval site Arondo (Senegal) are rather small compared with modern grains. This is also reported from Late Stone Age Tin-Akof and Oursi (both in northern Burkina Faso). A slight increase in size measurements is visible from Birimi (D’Andrea et al 2001) to Kursakata and again to Arondo (Gallagher 1999) although the number of measurements is too small to be of statistical validity. The Concerning the question of the history of domestication of Pennisetum glaucum, “non-shattering in ... seed crops is considered one of key differences between domesticated and spontaneous races” (Harlan 1992). This implies changes in the morphology of rachis and spikelets, which can only be detected in the threshing remains. “Grainbased characteristics” do not “necessarily date the beginning of cultivation” (Davies and Hillman 1992). Useful archaeobotanical features for domestication in naked grains are the shape and the size (Harlan 1992, Smith 1998, Zohary and Hopf 2000). Most authors describing domestication processes in the Near East regard the grain size as the most important feature for domestication. In these publications the definition of the word “size” is not always clear, whether it means the length or other dimensions. A more detailed view reveals that for wheats and barleys the shape of caryopses provides the evidence of whether grains were of the wild or the domestic type (Zeist 1976, Zeist and Bakker-Heeres 1985, Zeist and De Roller 1994, Zohary and Hopf 2000). The shape of the wild types is narrower than in the domesticated forms. The result of the analysis of the small P. glaucum (L.) R. Br. caryopses of Kursakata is that they are assumed to be domesticated because of their club-shaped outline and their correspondence in the T/B index with modern domesticated P. glaucum caryopses. Several reasons can be put forward to explain their smallness. Shrinking during the carbonisation process is one conjecture, but the difference to modern caryopses is too big to explain their small size (Nesbitt 1997). The grains might have come from the end of the ears, but if so, the number of small ones should be few in comparison with the rest. Or the grains are from P. glaucum in an early domesticated form. The investigations of grain sizes of P. glaucum in different archaeobotanical records now show that the first step in domestication visible in caryopses is the change in outline. The shape of the grains seems to be more important than their size, length, breath and thickness for the domesticated stage (Neumann et al. 1996, D’Andrea et al. 2001). However, in the process of selection for human consumption, the club-shaped form means an increase in volume and weight. The length of the grains seems to have increased in a second step. The increase of the size in time might also reflect improved cultivation methods. Caryopses of shibra weeds and pearl millet may look similar in shape. For the interpretation of domestication they do not play a role because their occurrence in the archaeobotanical record only proves the existence of domesticated forms (D’Andrea et al. 2001). 192 Conclusions Not only in Kursakata, but also in several other published archaeobotanical records, small grains of Pennisetum glaucum (domesticated pearl millet), looking like small modern ones, were observed. They may represent an early domesticated stage of this cereal. The records of the earliest pearl millet grains (Dhars Tichitt in southeast Mauretania, Birimi in northern Ghana) are still few in number and widely spaced over West Africa. They do not yet allow a plausible synthesis of the expansion of its cultivation. Kursakata is a relatively young site compared with these two other sites. To prove the hypothesis that agriculture first developed at the southern fringe of the Sahara (Harlan 1971), more archaeobotanical investigations of early sites are needed. At the beginning of agriculture in West Africa, pearl millet seems to be the only domesticate, continuing for a long time. At the same time, an extended number of wild grasses was collected and yet, no domestication features can be discovered in these species up to today. This indicates an important difference to the history of the crops of the Near East, where a simultaneous domestication of a combination of cereals and pulses is known. Part 2: Catalogue of the identified taxa The taxa described in this catalogue appear in alphabetical order of families and within these of the genera. The nomenclature follows the Flora of West Tropical Africa (FWTA 1954–1972) with the exception of Pennisetum glaucum (L.) R. Br. (in FWTA: P. americanum (L.) K. Schum.). If newer synonyms exist, they follow the name in brackets with citation of the author. The identification of the taxa is based on the reference collection of the Institute for Pre- and Protohistory at Frankfurt University, African Archaeology and Archaeobotany. This reference collection contains seeds and fruits from 850 species. For the genus Pennisetum the herbarium of the “Botanischer Garten und Botanisches Museum Berlin Dahlem” was consulted, which includes a “Togo Herbarium”. For each genus mentioned, the available species in the collections are noted to illustrate the species the subfossil seeds and fruits were compared with. Sometimes only very few specimens were available. Measurements of well preserved subfossil seeds are given in millimetres in the order: length (L), breadth (B), thickness (T) or diameter. The scale in the figures and the plate always equals 1 mm. All subfossil seeds are preserved in a carbonised condition if not separately noted. Boraginaceae Heliotropium cf. subulatum (Hochst. ex A. DC.) Vatke. Number of specimens: 3 at two levels (Figs. 4 , no. 1 and 5, nos. 1 and 2). The dorsal margin of the trigonous nutlets is keeled but not winged, the reticulate surface has 9 isodiametric cells in a row along the back, the hilum on the ventral side is curved. The strongly marked ventral side with depressions or grooves which follow the outline of the seed resembles no other species of the reference collection. Nevertheless, its identification has to remain in an uncertain status because the characteristic cells on the dorsal side could not be found in the extant species and in addition, other possible species occurring in northern Nigeria are absent from the reference collection. This Heliotropium species is also recorded from Arondo, Senegal (Gallagher 1999). Measurements of the two complete nutlets: L 1.5–1.8, B 1.0, D 0.8–0.9 The seeds available in the reference collection are: Heliotropium bacciferum (1.5 mm long, outer surface nearly smooth with two veins running down the back, inner face wrinkled with a curved hilum), H. subulatum (1.8 mm, wrinkled outer surface, inner side with depressions or grooves which follow the outline of the seed, relatively symmetrical), H. strigosum (1.3 mm long, spherical with smooth surface), H. supinum (L ca 3 mm, ventral side flat, hilum in the middle of the ventral side, more or less straight). Heliotropium sp. Number of specimens: 7 in 4 levels. Trigonous nutlets with ovate outline, the dorsal side convex and broader than the inner walls, the ventral side shows a rough surface. All sides are covered with wrinkles. A wrinkled wing runs around the dorsal side. Measurements of the complete nutlets (n=3): L 2.1– 2.8, B 1.2–2.0, D 0.9–1.1 Similar to the seed reported for Nabta Playa, southern Egypt (Wasylikowa 1997, PL. 3, nos. 1–3) as cf. Heliotropium sp. Capparidaceae (Capparaceae, Burkill 1985) Gynandropsis gynandra (L.) Briq. (Cleome gynandra L., Burkill 1985). Number of specimens: 1 (Fig. 5, no. 3). One incomplete circular seed with both sides slightly convex, the micropylar end overlapping the other end completely, forming a spiral, but not becoming flat like the bill of a parrot as in the genus Cleome. The surface is reticulate with rectangular cells in parallel rows, without any additional sculptures like seeds of Cleome. Measurements: Maximum diameter 1.2 mm, thickness 0.6 mm. Available species studied in the reference collection are: Gynandropsis gynandra with a diameter of 1.3 to 1.4 mm, 0.5 mm thick, which is the only species without additional ridges on the reticulate surface; Cleome monophylla, with a diameter of 1.5 mm and radial ridges starting at the micropylar end; C. scaposa, diameter 0.8 mm, C. villosa, diameter 1.3 to 1.1 mm, all with additional sculptures on the somewhat reticulate surface. 193 Fig. 4 Carbonised remains from Kursakata, Nigeria (Late Stone Age and Iron Age). 1 Heliotropium cf. subulatum seen from ventral, lateral and dorsal side, 2 Commelina cf. benghalensis seen from the dorsal, lateral and ventral side, 3 Fimbristylis hispidula vel Bulbostylis congolensis, 4 cf. Carex sp. seen from the lateral side and from the base, 5 Cyperaceae indet. seen from the lateral side and from the apex, 6 Trianthema pentandra seen in dorsal, ventral and lateral view, 7 Dactyloctenium aegyptium, seen from dorsal, ventral and lateral side, 8 cf. Cyperus sp. tuber, 9 Eleusine indica seen from dorsal, ventral and lateral side, 10 Eragrostis cf. pilosa seen from ventral, dorsal and lateral side, 11 Gramineae indet., ventral, dorsal and lateral side, 12 Paniceae indet., type 1 seen from ventral, dorsal and lateral side, 13 Oryza sp. seen from lateral and dorsal side and in cross section Caryophyllaceae/Molluginaceae Commelinaceae Caryophyllaceae/Molluginaceae indet. Number of specimens: 1. Half of a flattened, nearly circular seed, with an extension of the radicula, short undulating irregular ridges on the surface. Measurements: 1.51.3 mm. Commelina cf. benghalensis L. Number of specimens: 8 at 6 levels (Figs. 4, no. 2 and 5, no. 4). The well preserved seeds in the half-spherical shape show a round, deep depression on the convex side and furrows. Crosswise arranged furrows or ribs give the picture of nearly rectangular panels. On the opposite flat side a thin longitudinal structure exists (not visible in Fig. 4, no. 2). 194 Fig. 5 Photographs of seeds and fruits from Kursakata, Nigeria (Late Stone Age and Iron Age). 1 Heliotropium cf. subulatum seen from dorsal side; 2 from ventral side, 3 Gynandropsis gynandra seen from lateral, 4 Commelina cf. benghalensis seen from lateral, 5 and 6 Fimbristylis hispidula vel Bulbostylis congolensis, uncharred, 7 cf. Bulbostylis congolensis, uncharred, 8 cf. Carex sp., 9 Trianthema pentandra, seen from lateral side, 10 cf. Cyperus sp., tuber, 11 Oryza sp., seen from lateral side, 12 and 13 Hibiscus esculentus, 12 seen from ventral and 13 seen from lateral side, 14 Cenchrus biflorus, seen from dorsal side, 15 Digitaria sp., seen from dorsal side, 16 and 17 Echinochloa colona/E. pyramidalis, 16 seen from dorsal and 17 from ventral side; 18 Eleusine indica, seen from dorsal side, 19 Eragrostis cf. pilosa, seen from lateral side, 20 Paniceae indet., type 2, seen from dorsal side, 21 and 22 Mimosaceae/Caesalpinaceae indet., 21 seen from outside and 22 from inside, 23 and 24 Pennisetum glaucum, two caryopses, dorsal side, 25 Pennisetum sp. (wild), seen from dorsal side, 26 and 27 Hibiscus trionum, 26 seen from ventral and 27 seen from lateral side, 28 Ziziphus mauritiana vel Ziziphus spina-christi, fragment of kernel seen from inside, 29 and 30 cf. Aeschynomene sp., 29 seen from ventral and 30 from lateral side, 31–33 Celtis integrifolia, uncharred kernel, seen from two lateral sides and the top, 34 KUR-1 type, 35 KUR-2 type, 36 and 37 KUR-6 type seen in two views, 38 Papilionaceae indet., type 3, seen from lateral side, 39 Vitex simplicifolia, kernel Measurements (n=5): L 2.0–2.8, B 1.3–2.0, D 0.8–1.5 Seeds of the genus Commelina have more or less the shape of half a ball with a deep round depression in the centre of the convex side. They are flat on the opposite side where the seed was attached to the placenta. Very characteristic are the radial furrows overlain by a reticulate surface sculpture on the upper side. The hilum is formed as a narrow line in the middle of the seed. The length is half that of the seed. Commelina benghalensis is about 2.5 mm long, 1.8 mm wide and 0.8 mm high, the smooth reticulate sculpture stressed by raised points mainly on the rims. Seven to twelve shallow furrows can be counted. The reference collection contains the species Commelina benghalensis, C. diffusa, C. erecta, C. forskalaei, C. nigritana, C. subulata (syn. Cyanotis lanata). Additionally the following species are reported for northern Nigeria of the all in all 23 species noted in the FWTA: C. africana, C. macrospatha, C. capitata, C. zambesica, C. 195 petersii, C. schweinfurthii, C. bracteosa, C. erecta, C. nigritana and C. aspera. Commelina benghalensis shows more furrows than C. erecta and C. subulata which both reach a length of not more than 2 mm. Its reticulate surface sculpture is smooth compared with the winged network of C. diffusa and C. nigritana which do not show distinct furrows. The surface sculpture of the seed of C. forskalaei is not visible because it is fused with the pericarp. Commelina cf. benghalensis was also found in Arondo, Senegal by D. Gallagher (1999). Cyperaceae Fimbristylis hispidula (Vahl) Kunth. (Bulbostylis hispidula (Vahl) Haines after Berhaut 1988) vel Bulbostylis congolensis De Wild. Number of specimens: 30 charred achenes in 11 levels (Fig. 4, no. 3); and 10 uncharred achenes in 5 levels (Fig. 5, nos. 5–6). The charred trigonous achenes are obovate to obcordate, with transversely undulate ridges. The base is narrowly elongated, the length of the fruits more than 1 mm. One side is a little bit broader than the others. The keels are mostly very prominent. The uncarbonised achenes are white in colour and similar in size and morphology to the charred ones. Two fruits have nodules along robust keels. Measurements (n=8): L 1.1–1.2, B 0.8–1.3, D 0.6–1.1 Modern achenes of Fimbristylis hispidula are obovate, trigonous with prominent keels, truncated or slightly notched at the apex, about 1–1.2 (–1.5) mm long, the surface marked by 6 to 12 transverse undulations. At both sides of the keels a row of distinct to faint nodules is discernible, sometimes no nodules are present. Achenes of Bulbostylis congolensis are similar in shape and size, with 8 to 12 transverse undulations. The keels are smaller than those of Fimbristylis hispidula and nodules never appear. The reference material available includes Fimbristylis cymosa (no transverse undulations and much smaller in size), F. debilis (mucronate; having a very short bristlelike tip), F. dichotoma (no transverse undulations), F. hispidula, F. pilosa (no transverse undulations). Of the genus Bulbostylis the collection contains Bulbostylis abortiva (much smaller, smooth surface), B. barbata (much smaller, smooth surface), B. coleotricha (smooth surface), B. congolensis, B. densa (with transverse undulations but much smaller), B. lanifera (smooth surface) and B. scabricaulis (shape ovoid, smooth surface). In Table 4 Fimbristylis spp. and Bulbostylis spp. are compared concerning the presence of transversal undulations on the achenes. cf. Fimbristylis hispidula vel Bulbostylis congolensis. Number of specimens: 1 charred inner part of a fruit. One charred trigonous specimen, obcordate, at the base narrowly elongated with adhering fragments of the outer rough surface, is very likely the inner part of a fruit of cf. Fimbristylis hispidula vel Bulbostylis congolensis. Measurements: 0.50.50.6 mm cf. Bulbostylis congolensis De Wild. Number of specimens: 1 (Fig. 5, no. 7). One of the achenes is probably cf. Bulbostylis congolensis because its base is not distinctly narrowly elongated, there are no nodules along the faint keels and the achene has three convex walls on which six rows of transverse ridges can be counted. Measurements: 1.01.00.9 mm cf. Carex sp. Number of specimens: 1 nutlet (Figs. 4, no. 4 and 5, no. 8). Measurements: 1.30.80.6 mm The trigonous fruit is long oval in shape with an acute apex, the base faintly elongated. Its surface is covered by a reticulate epidermal structure. Referring to the FWTA at least two species of Carex occur in northern Nigeria: C. preussii and C. neochevalieri, but no reference specimens were available. The fruit was also compared with fruits of the genus Cyperus which is very rich in species in West Africa. Available species with ripe nutlets in the reference collection are Cyperus amabilis, C. difformis, C. esculentus, C. haspan, C. iria, C. karlschumannii, C. reduncus, C. rotundus, C. tenuispica. cf. Cyperus sp. Number of specimens: 1 tuber (Figs. 4, no. 8 and 5, no. 10). The tuber has an oblong shape, is circular in crosssection and narrowed at the apex. A small furrow goes spirally around the tuber showing, faintly visible, some deeper nearly round impressions. Measurements: 7.05.05.0 mm Tubers are available from C. esculentus. Species of other genera were also studied, namely Eleocharis, Fimbristylis, Kyllinga, Lipocarpha, Mariscus, Pycreus, Rhynchospora, Scirpus and Scleria. Cyperaceae indet. Number of specimens: 2 uncharred nutlets (Fig. 4, no. 5). Measurements:1.31.11.1 mm The trigonous fruits are truncate and narrowed at the base. A reticulate structure of narrow cells in longitudinal rows covers the surface. There were no species in the reference collection matching this specimen. Ficoidaceae (Aizoaceae Burkill 1985) Trianthema pentandra L. (Zaleya pentandra (L.) Jeffry, Burkill 1985), Number of specimens: 8 in 5 levels (Figs. 4, no. 6 and 5, no. 9). The seeds are nearly circular in shape with a small elevation above the hilum. The hilum itself has a swollen surrounding. The surface is covered by parallel undulating ridges. Measurements (n=7): L 1.0–1.5, B 1.0–1.3, D 0.6–1.1 The reference collection contains seeds of Trianthema pentandra and T. portulacastrum. 196 Fig. 6 Charred seeds from Kursakata, Nigeria (Late Stone Age and Iron Age). 1–4 Four caryopses of Brachiaria sp.; 1 seen from dorsal and lateral side, 2–4 seen from dorsal, lateral and ventral side Gramineae (Poaceae) The grains of all Poaceae were found without glumes, in some cases, small remnants of those were adhering to the surface. Most of the subfossil caryopses have lost the basis with the hilum. Brachiaria sp. Tribe Paniceae. Number of specimens: 24 in 8 levels (Fig. 6, nos. 1–4). The oval caryopses, which are broadest slightly above the middle, can only be identified as belonging to the genera Brachiaria, Setaria or Urochloa when there are at least some adhering fragments of glumes with large wrinkles. This is the case in the 24 specimens described here. Together with an oblong hilum and a scutellum reaching up to more than half of the length of the caryopsis these seem to be characteristic features which occur only in these three genera. Brachiaria can be distinguished from Setaria by the broader outline, Brachiaria and Setaria are not as flat in profile as Urochloa. Specimens of this taxa are already described by Wasylikowa (1997) and Gallagher (1999). Measurements (n=3): L 1.2–1.8, B 1.0–1.1, D 0.6–0.8 The average L/B index is 145. Available species in the reference collection are Brachiaria deflexa, B. distichophylla, B. lata, B. stigmatisata, B. xantholeuca, Setaria pallide-fusca, S. verticillata and Urochloa trichopus. Cenchrus biflorus Roxb. Tribe Paniceae. Number of specimens: 1 (Figs. 7, no. 1 and 5, no.14). Compared with other Paniceae, caryopses of the genus Cenchrus are quite large, ovate and faintly apiculate (pointed at the end). The outline of Cenchrus biflorus is asymmetrical. The triangular scutellum reaches much more than two thirds of the length of the caryopsis. No other species of Paniceae was found with a similar size and outline of grains. Measurements:1.81.30.8 mm, L/B index is 138. Available species in the reference collection are Cenchrus biflorus, C. ciliaris and C. setigerus. Caryopses of C. ciliaris are smaller, narrower and more flattened, but Fig. 7 Charred seeds from Kursakata, Nigeria (Late Stone Age and Iron Age). 1 Cenchrus biflorus seen from ventral, lateral and dorsal side, 2 Digitaria cf. ciliaris seen from dorsal, lateral and ventral side, 3–5 three caryopses of cf. Digitaria sp. each seen from dorsal, lateral and ventral side the scutellum is larger than in C. biflorus. Caryopses of C. setigerus are also smaller and more triangular in shape. Clearly C. biflorus caryopses are large and asymmetrical. Dactyloctenium aegyptium (L.) Beauv. Tribe Eragrostideae. Number of specimens: 9 in 6 levels (Fig. 4, no. 7). The caryopses are very characteristic in their triangular shape with truncated ends when seen from the lateral side, and the surface which is strongly sculptured by parallel ridges. The caryopsis cannot be confused with any other species. Nevertheless the grains are larger than those of the reference collection. Measurements (n=9): L 0.75–1.0, B 0.5–0.75, D 0.3– 0.5 The average L/B index is 118. Dactyloctenium aegyptium is also described by Gallagher (1999). Digitaria cf. ciliaris L. Tribe Paniceae. Number of specimens: 2 in 2 levels (Fig. 7, no. 2). The two charred caryopses without glumes are narrow long-oval in outline and acute at the apex. The scutellum reaches less than half of the grain length. Both ventral and dorsal sides are convex, the thickest point at the middle of the grain. The surface of the caryopses shows longitudinal cell rows which is, besides the narrow outline (L/B index 300), an important characteristic feature for this species. Measurements: 1.80.60.3 mm, L/B index is 300. The species compared with in the Frankfurt reference collection are Digitaria ciliaris, D. exilis, D. horizontalis, D. longiflora, D. lecardii, D. gayana, D. ternata and D. delicata. Modern caryopses of the genus Digitaria are narrow (with some exceptions like Digitaria exilis), most of them are flattened with an acute apex. The hilum is obovate, the scutellum reaches one third of the length of the caryopses. cf. Digitaria sp. Number of specimens: 40 in 14 levels (Figs. 5, no. 15 and 7, nos. 3–5). The charred caryopses without glumes are narrow obovate to long-oval with a narrowed to acute apex. The ventral side is not as convex as the dorsal side, with the 197 Fig. 8 Charred seeds from Kursakata, Nigeria (Late Stone Age and Iron Age). 1–4 Echinochloa colona/E. pyramidalis seen in three views, 5 Echinochloa sp. seen from dorsal and lateral side, 6 and 7 Pennisetum sp. (wild) both seen from dorsal and lateral side highest point at the middle of the grain; the scutellum never reaches half the length of the caryopsis. This outline is typical for the genus Digitaria, but without further details, for example surface structure, identification to species level is not possible. Measurements (n=7): L 1.1–1.5, B 0.5–1.0, D 0.5–0.6 The average L/B index is 148. Digitaria sp. is also reported from Nabta Playa, southern Egypt (Wasylikowa 1997), where the grains are somewhat longer and broader. Echinochloa colona (L.) Link / E. pyramidalis (Lam.) Hitchc. and Chase. Tribe Paniceae. Number of specimens: 26 in 7 levels (Figs. 5, nos. 16–17 and 8, nos. 1–4). The caryopses are nearly circular to broad oval in outline and sometimes narrowed or faintly truncated at the apex. The ventral side is completely flat, the dorsal side strongly convex with the highest point in the middle or slightly above the middle of the caryopses. The scutellum reaches more than two thirds of the length of the caryopses. In one of the carbonised caryopses, fragments of the smooth lemma with rows of fine, longitudinal cell rows were preserved. The caryopses of Panicum laetum, which are similar in size, never have a flat ventral side and those of Setaria verticillata possess an acute apex. Measurements (n=7): L 1.25–1.75, B 1.0–1.25, D 0.6– 0.8 The average L/B index is 134. In the reference collection caryopses of Echinochloa colona, E. pyramidalis, E. obtusiflora and E. stagnina were available. Echinochloa colona and E. pyramidalis cannot be distinguished from each other, both show the same shape of hilum which is broad ovate. The grains of E. stagnina are larger than the others. Caryopses of Echinochloa colona described from Nabta Playa are very similar in shape and L/B index but are somewhat smaller (Wasylikowa 1997). Echinochloa sp. Number of specimens: 5 in 1 level (Fig. 8, no. 5). The caryopses are flat at the ventral side and convex at the dorsal side, the broadest in the middle. The hilum is nearly circular, but mostly not visible because the basal part is often broken off the seed. Eleusine indica (L.) Gartn. Tribe Eragrostideae. Number of specimens: 12 in 9 levels (Figs. 4, no. 9 and 5, no. 18). The very easily recognisable caryopsis is somewhat triangular in shape, laterally flattened, with a trigonal cross-section. The apex is truncate, the ventral groove runs from shortly above the hilum up to the apical end, and is the broadest in the middle. Six to ten ridges run over the lateral sides to the ventral groove. The hilum is circular. The triangular scutellum is located at an acute angle to the dorsal side. Measurements (n=9) L 0.75–1.5, B 0.3–1.0, D 0.3–1.0 The average L/B index is 154. In the reference collection Eleusine indica and E. coracana were available. Specimens of Eleusine indica are also described from Arondo, Senegal (Gallagher 1999). Eleusine cf. coracana (L.) Gaertn. Tribe Eragrostideae. Number of specimens: 1 The grain of E. coracana, compared with E. indica is a little larger, has a more spherical outline and no ventral groove. The ridges are faintly visible, the small elevations are mostly arranged in lines. The hilum is circular, the scutellum triangular in shape and twice as large as in E. indica and placed at a very acute angle to the dorsal side. Measurements: 1.41.41.2 mm, L/B index is 100. Eragrostis cf. pilosa (L.) P. Beauv. Tribe Eragrostideae. Number of specimens: 33 in 8 levels (Figs. 4, no. 10 and 5, no. 19). The very small caryopses are oval in outline, the narrow scutellum reaches at an acute end, at least half of the grain length. Most of the caryopses are larger than those of E. pilosa in the reference collection. Measurements (n=4): L 0.8–1.0, B 0.3–0.4, D 0.4– 0.75. The average L/B index is 288. Species seen in the reference collection are Eragrostis pilosa and E. turgida. Gramineae indet. Number of specimens: 84 in 19 levels (Fig. 4, no. 11). All naked caryopses which could not be identified do not belong to the described taxa. Most of them are very small (L: 1 mm, B: 0.5 mm), some very badly preserved. Gramineae indet., culms. Number of specimens: 731 in 23 levels. Charred fragments of culms, circular in cross section and with longitudinal grooves. Oryza sp. L. Tribe Oryzeae. Number of specimens: 407 (including fragments) in 26 levels (Fig. 4, nos. 13 and 5, 11). 198 The rice caryopses are oblong and laterally flattened, the scutellum reaches one sixth to a quarter of the length of the caryopsis, the hilum lies more or less in the middle of the base. The apical end is bluntly pointed, the tip deriving from the former style. The lateral sides are notched by the imprints of the glumes. Without glumes, the differentiation between the species seems to be very difficult, even the domesticated species cannot be distinguished from the wild ones with certainty. Nevertheless caryopses of O. longistaminata, seen in lateral view, show beyond the acute apex a small shoulder at the side of the scutellum and thus seem to be distinguishable from the other species of the genus. Measurements (n=4): L 5.0–7.0, B 1.0, D 1.5–2.2 The average L/B index is 322. The reference collection contains Oryza barthii A. Chev., O. glaberrima Steud., O. longistaminata A. Chev. & Roehr., O. punctata Kotschy ex Steud. and O. sativa L., which means all Oryza species growing in Nigeria according to the FWTA (1954–1972) and Clayton (1960). Six of the seven species mentioned in the Flora of West Tropical Africa grow wild in West Africa, O. glaberrima is the indigenous domesticated species in Africa. Although O. punctata is reported only for the southern part of Nigeria (FWTA) it was collected by the authors in the Lake Chad basin. O. sativa was introduced to Africa only 500 years ago and is therefore excluded from the possible species. The identifications of the subfossil caryopses remain unclear because only few grains were available for comparison. Paniceae indet. Tribe Paniceae. Most of the caryopses clearly identifiable as Paniceae, but not belonging to the genus Pennisetum, had to remain unidentified. Typical of the grains of this group are a broad oval outline and the dorsal-ventral compression. In contrast, most of the other Gramineae genera are laterally compressed. The dorsal side of Paniceae caryopses is mostly convex, the ventral side more or less flattened. The scutellum reaches half the length of the grain, sometimes more. Paniceae indet., type 1. Number of specimens: 462 in all levels (Figs. 4, no. 12 and 9, nos. 1–5). The caryopses have a broad oval outline and a narrow profile seen from the lateral side. They resemble more Panicum or Brachiaria in the reference collection than Echinochloa, Setaria or Digitaria. The different shapes figures probably represent different species. Paniceae indet., type 2. Number of specimens: 58 in 13 levels (Figs. 5, no. 20 and 9, nos. 6–8). The grains resemble very much those of the genus Echinochloa with the convex dorsal and very flat ventral side and the scutellum reaching half the length of the grain. But the slightly acute apex never occurs in Echinochloa and no other genus in the reference collection matched. The different shapes probably represent different species. Pennisetum glaucum (L.) R. Br. (after Burkill 1995; Pennisetum americanum (L.) K. Schum. in FWTA). Tribe Fig. 9 Charred seeds from Kursakata, Nigeria (Late Stone Age and Iron Age). 1–5 Paniceae indet. type 1, seen from dorsal, lateral and ventral side, 6–8 Paniceae indet. type 2, seen from dorsal, lateral and ventral side Paniceae. Number of specimens: 823 caryopses and 2 involucres in 19 levels (Figs. 5, nos. 23–24 and 11, no. 1). The charred caryopses are spherical to club shaped (and nowhere flattened). Sometimes the base is narrowed to acute. The scutellum takes half of the grain length, the grain is thickest at the apex of the scutellum. The embryo is deeply embedded. In most cases the base with the hilum is not preserved. The grains could be divided into two groups: those with a length of more than 2 mm which are mostly spherical, and smaller grains, mostly club shaped. They were both identified as domesticated Pennisetum glaucum (syn.: Pennisetum americanum ssp. americanum after Brunken 1977) even though they are much smaller than the modern grains of domesticated forms or of shibras (weedy subspecies of Pennisetum glaucum) in the Frankfurt reference collection (see part 1, Fig. 3). Measurements of complete caryopses (n=8): L 1.2–2.8, B 0.8–2.4, D 0.5–2.0 Average D/B index is 89. Measurements of caryopses where the hilum is not preserved (n=21): L 1.0–2.1, B 0.6–2.0, D 0.5–2.0, D/B 0.6–1.0 Average D/B index is 86 (see Table 3). Nearly 70% of the subfossil grains, most of them without scutellum, are between 1 and 2 mm long and only few are shorter or longer. Measurements of 8 specimens L (without scutellum): 1.86 (2.8–1.2) mm, measurements of 29 specimens B, D (with and without scutellum): B: 1.17 (2.4–0.6) mm, D: 1.0 (2.0–0.5) mm. In modern ears, which can reach 1.5–2 m length, grains are always smaller at the end and the base than in 199 the middle of an ear and they vary from spherical to club shaped. Some small grains (L: 2,2 mm) of modern domesticated Pennisetum were found in the herbarium of the botanical garden in Berlin in a record from Libya (Coll. J. Lonard 4695 5.10.1968) in an ear of 4 cm length. In modern grains of domesticated form, measurements of 30 specimens of the reference collection are: L: 3.5 (5.0–2.0) mm, B: 2.0 (2.5–1.2) mm, D: 1.8 (1.0–2.4) mm, average L/B index is 177 (Fig. 2). Average D/B index is 90 (Fig. 2). Domesticated pearl millet is also described from Arondo, Senegal, where the average measurements as well as the calculated T/B index are larger (Gallagher 1999). Many domesticated pearl millet grains were recovered in Birimi (northern Ghana). Their T/B index seems to be very similar to the one of Kursakata and most of the grains are as small as the smallest grains from Kursakata (D’Andrea et al. 2001). Involucres The charred involucres consist of a swollen part like a ball where the bases of the bristles are inserted. In the middle of the ball a short stalk (pedicel) is visible which carries the spikelet. The involucre is carried by a stalk (peduncle) which does not exist in the wild progenitor (Brunken et al. 1977). Pennisetum sp. (wild) Number of specimens: 59 in 15 levels (Figs. 5, no 25, 11, no. 2, 8, nos. 6–7) . Important features for identification of the ventrally flattened wild Pennisetum caryopses are, besides the length and breadth, the length of the scutellum and the form of its apical end. The length of the scutellum is between half and two third of the length of the caryopses, the apical end is flat to truncated. Shape oval to oblong. The different shapes presumably represent different species. Measurements (S = Length of scutellum) (n=12): L 0.8–1.9, B 0.5–1.0, D 0.3–0.7, S 0.4–1.0 Species compared with are Pennisetum fallax (Fig. & De Not) Stapf & Hubbard, P. hordeoides (Lam.) Steud., P. pedicellatum Trin., P. polystachion (L.) Schult., P. purpureum Schumach., P. ramosum (Hochst.) Schweinf., P. setaceum Forssk.) Chiov. P. trachyphyllum Pilger and P. violaceum (Lam.) L. Rich. Modern grains of P. hordeoides, P. pedicellatum, P. polystachion, P. trachyphyllum are long-oval, ventrally and dorsally flattened with a rounded or acute apex, with their broadest point in the middle of the grain; the scutellum reaches slightly more than half of the grain length. Caryopses of P. setaceum are oblong and have a rounded to more or less truncated apex, their broadest point is near the apex, and the scutellum reaches slightly more than half of the grain length. P. fallax, P. purpureum, P. violaceum, P. ramosum are oblong and dorsally flattened, the scutellum reaches more than half of the grain length, their apical end is truncated. Panicum subalbidum which is similar in size has an acute apex. Wild races of Sorghum are much larger and more rounded to obovate in outline. Similar Digitaria species never show a scutellum reaching more than half of the grain length. The broadest part of the grain is in the lower half. Small specimens of Tragus can be confused with the small specimens of Pennisetum. Most of the grains of wild Pennisetum sp. in the Kursakata samples are similar to the grains of wild species with a more or less truncated apex, comprising the perennials, for example P. purpureum and the supposed wild progenitor of pearl millet P. violaceum (see Part 1). Sorghum sp. Moench. Tribe Andropogoneae. Number of specimens: 19 in 10 levels (Fig. 11, no. 3). The caryopses of Sorghum sp. are oblong in outline and broadest in the upper part of the grain. They are dorsally and even more ventrally flattened, the thickest in the upper part of the scutellum and nearly always show a short point at the apical end, deriving from the former style. The surface shows narrow longitudinal wrinkles. The hilum is oval and only faintly embedded. The ovate scutellum reaches more than half of the length of the grain. Some of the grains show a keel-like wing running around the margin when seen from the ventral side. Measurements (n=4): L 2.0–3.0, B 1.25–1.75, D 0.5– 1.25 The species available in the reference collection (taxonomy follows Harlan and de Wet 1972, de Wet 1978) are classified into several cultivated (Sorghum bicolor ssp. bicolor) and truly wild taxa (S. bicolor ssp. arundinaceum), including the races aethiopicum and verticilliflorum. Sorghum bicolor ssp. arundinaceum was found in Nabta Playa, described in detail by Wasylikowa (1997, p. 122). The grains from Kursakata bear a strong resemblance to those, but spikelets giving better diagnostic criteria are absent. Malvaceae Hibiscus esculentus Linn. (Abelmoschus esculentus (L.) Moench (Burkill 1985–1997). Number of specimens: 16 in 7 levels (Figs. 5, nos .12 and 13 and 11, no. 6). The subfossil seeds of Kursakata are spheroid and show the typical wrinkled area around the narrow line of the hilum. The seeds have often lost their testa, and show tiny dots on the exposed surface. The preserved layers show polygonal cracks giving the seed surface a very characteristic appearance. Measurements (n=3): L 1.8–3.5, 2.0–3.0, D 1.0–2.5 In the reference collection, seeds of the genus Hibiscus are spheroid or flattened triangular to discoid in shape. 33 species are given in the FWTA. The reference collection contains Hibiscus asper, H. cannabinus, H. esculentus, H. trionum H. sabdariffa, H. scotellii and H. squamosus. The only one with spheroid seeds is Hibiscus esculentus (Ochra). Around the elongated narrow hilum characteristic radial small grooves form a disk-like wrinkled area. This area is covered by a membrane and invisible in untreated seeds. The surface of the seed carries small pointed projections in rows running around the seed, from the hilum over the back. 200 The seeds have an average diameter of around 4 to 5 mm. The seeds collected in the surrounding of Kursakata from so called wild Ochra growing spontaneously at the edge of fields show exactly the same structures, but are smaller in diameter, around 3 mm. Hibiscus trionum L. Number of specimens: 1 (Figs. 5, nos. 26 and 27 and 11, no. 4). The seed is triangular due to the projecting radicula. The hilum is shorter than that of H. esculentus but reveals the same wrinkled area. Measurements: 2.01.71.1 mm The surface of the slightly flattened modern seeds, discoid to triangular in shape, is smooth or with few small papillae. It shows a similar radially wrinkled area around the elongated hilum to H. esculentus. A projecting radicula makes a confusion with Fabaceae seeds possible, but can be distinguished by the wrinkles around the hilum. The average diameter is around 2.5 mm and therefore clearly smaller than H. esculentus. cf. Malvaceae indet. Number of specimen: 2 (Fig. 11, no. 8). The laterally flattened seeds are oval in shape when seen from the lateral side, with a keel running in the middle of the back, flanked by two wings forming the outline of both lateral sides. The seeds resemble the European genus Malva but nothing similar was found in the Frankfurt collection. Measurements: 0.750.50.5 mm, 0.750.50.4 mm The reference collection contains several species of the genera Abutilon, Gossypium, Cienfuegosia, Hibiscus, Pavonia, Sida, Urena and Wissadula. Mimosaceae Acacia nilotica (L.) Willd. ex Del. vel Parkia biglobosa (Jacq.) Benth. Number of specimens: 1 in sample 17 (Fig. 10, no. 1). The seed is laterally compressed. The lateral face of the fragment shows more than half of the complete seed and a nearly round shape can be reconstructed. The size of the seed is larger than in most of the other Acacia species. The furrow typical for Acacia species (areole) runs parallel to the margin at a distance of about 1.2 mm. This is the characteristic feature to distinguish A. nilotica from other Acacia species having seeds of round shape and similar size. Parkia biglobosa is comparable in shape, size, position and course of the areole, whereas the shape of the seed and the course of the areole at the micropylar end, which is not preserved, differ from Acacia nilotica. Measurements: sample 17 (fragment): 6.34.51.8 mm Seeds of Mimosaceae can be identified by their size and shape and by the position and size of the areole which can be found on both lateral faces of the seeds. Species compared with in the reference collection: Acacia albida, A. ataxacantha, A. dudgeoini, A. gourmaensis, A. hockii, A. macrostachya, A. mellifera, A. nilotica, A. nubica, A. raddiana, A. senegal, A. seyal, A. sieberiana, A. tortilis, Dicrostachys glomerata, Entada Fig. 10 Charred seeds from Kursakata, Nigeria (Late Stone Age and Iron Age). 1 Acacia nilotica vel Parkia biglobosa seen from outside, 2 Mimosaceae/Caesalpiniaceae seen from outside and inside, 3 and 4 Mimosaceae/Caesalpiniaceae, two specimens each seen from inside and outside abyssinica, E. africana, Neptunia oleracea, Prosopis africana, and Parkia biglobosa. Mimosaceae/Caesalpiniaceae indet. Number of specimens: 8 in 5 levels (Figs. 5, nos. 21–22 and 10, nos. 2–4). The seeds, most of them incomplete or broken, were identified, according to their size and shape, with certainty as belonging to Mimosaceae or Caesalpiniaceae. Identification to the species level was not possible. Some of the fragments show a part of the areole, some an incomplete hilum. Measurements (n=4): Sample 13, 22, 27 (2x), L 6.0– 7.8, B 4.8–6.2, D (half seed) 1.8–2.5 Genera in the reference collection are Acacia, Bauhinia, Dichrostachys, Entada, Neptunia, Parkia, Prosopis, Tetrapleura. Papilionaceae (Leguminosae, Fabaceae) One small and six larger types of Papilionaceae seeds could be identified. In the larger ones the testa is mostly missing. cf. Aeschynomene sp. L. Number of specimens: 2 in 2 levels (Figs. 5, nos. 29–30 and 12, no. 1). The seeds are broadly crescent-shaped, laterally flattened, with a distinct extended micropylar end and an oval hilum. 201 Fig. 11 Charred seeds from Kursakata, Nigeria (Late Stone Age and Iron Age). 1 Pennisetum glaucum seen from dorsal and ventral side and in cross section, 2 Pennisetum sp. seen from dorsal, ventral and lateral side, 3 Sorghum sp. seen from ventral, dorsal and lateral side, 4 Hibiscus trionum seen from lateral, ventral and opposite lateral side, 5 KUR-3 type seen from different views, dorsal, ventral, lateral, from the base and from the apex, 6 Hibiscus esculentus seen from lateral and ventral side, 7 KUR-2 type seen from three views, 8 cf. Malvaceae indet. seen from lateral side and two views on the back, 9 Vitex simplicifolia seen from two sides, 10 KUR-6 type, 11 KUR-1 type seen from lateral side and from the base Measurements: 2.41.41.4 mm, 2.82.11.5 mm Species in the reference collection compared with are: Aeschynomene indica, A. lateritia and A. sensitiva. cf. Indigofera sp. L. Number of specimens: 1. Seed with a rectangular outline, both ends truncated, the faintly visible hilum positioned in one corner, the surface uneven. The radicula is not protruding. Measurements: 1.51.11.1 Charred seeds of Indigofera types are also reported from Nabta Playa (Wasylikowa 1997). Trifolieae-type. Number of specimens: 11 seeds in 8 levels. Outline of the seeds oval to trigonous, seeds laterally flattened, surface reticulate to tuberculate, the hilum is minute and circular, but often missing. In size and shape seeds of this type resemble the European Trifolium repens. Measurements (n=7): L0.7–1.0, B 0.6–0.9, D 0.5–0.75 A great number of charred Trifolieae seeds with the L/ B index of 123 are reported from Nabta Playa (southern 202 Measurements: 2.01.71.2 mm, 2.01.710 mm. Papilionaceae indet., type 5. Number of specimens: 1. Seed in dorsal view broad oval, in lateral view nearly rectangular in shape, truncate at both ends, hilum round nearly taking half of the lateral side. Measurements: 1.91.41.2 mm Papilionaceae indet., fragments. Number of specimens: 23 fragments in 9 levels. The fragments could be identified as belonging to Papilionaceae, but it was not possible to identify them to genus level. Portulacaceae Portulaca oleracea L. Number of specimens: 1. The seed is circular in shape with a small extension of the tip of the radicula, laterally flattened, the surface shiny with four rows of star-like cells running in circles on the lateral face. Measurements: 0.50.50.2 mm Rhamnaceae Fig. 12 Charred seeds from Kursakata, Nigeria (Late Stone Age and Iron Age). 1 cf. Aeschynomene sp. seen from ventral, lateral and dorsal side, 2 Papilionaceae indet., type 1, seen from ventral, lateral and dorsal side, 3 Papilionaceae indet., type 2, seen from ventral, lateral and dorsal side Egypt, Wasylikowa 1997). The seeds from Kursakata are smaller, their L/B index is 110. The genus Trifolium is reported in the FWTA with four species, but no reference material was available. Papilionaceae, type 1. Number of specimens: 1 (Fig. 12, no. 2). Seed with an obovate outline, radicula not protrude, hilum round with radial small furrows. Measurements: 2.51.81.8 mm Papilionaceae indet., type 2. Number of specimens: 1 (Fig. 12, no. 3). Seed slightly kidney-shaped (reniform), broad, a part of the long and broad hilum is visible and parts of the smooth testa. Measurements: 3.82.52.5 Papilionaceae indet., type 3. Number of specimens: 6 in 4 levels (Fig. 5, no. 38). The shape of the seeds is nearly cylindrical, slightly reniform, flattened with both ends truncated, the pointed radicula is extended. Measurements (n=6): L 2.3–3.0, B 1.5–2.0, D 1.0–1.8 Papilionaceae indet., type 4. Number of specimens: 2 in 1 level. Seeds crescent-shaped, the radicula is extended, in both seeds the hilum is missing. Ziziphus mauritiana (L.) Desf. vel Ziziphus spina-christi Lam. Number of specimens: 35 fragments in 15 levels (Fig. 5, no. 28). Ziziphus is represented by fragments of the stones, which show the characteristic outer surface and sometimes the inner surface of the seed chambers. The surface of the globose stones is “characterised by network-like furrows” as described in Neumann et al. (1998, p. 60; Fig. 3, no. 2) from Burkina Faso. They contain two seeds. The authors distinguish Z. mauritiana/ spina-christi from other Ziziphus species occurring in West Africa by their stones with a finer sculpture (smaller elevated interspaces) and broad, more or less smooth points of septae (Z. lotus) or conspicuous prominent bulge-like outgrowths (Z. abyssinica, Z. mucronata). The average diameter of Z. cf. spina-christi in the reference collection is 8.5 mm while the one of Z. mauritiana is 9 mm. The inner surface of seed chamber is covered with criss-crossing striae resembling the pattern visible on the seed surface in Malus domestica. Ulmaceae Celtis integrifolia Lam. Number of specimens: 3 charred fruit stones in one level, 294 uncharred fruitstones and fragments of fruit stones in 11 levels (Fig. 5, nos. 31–33). Stones are rarely charred as described also from Burkina Faso by Neumann et al. (1998, p.61; Fig. 3, no. 1). On charred as well as on uncharred remains “sometimes the reticulate network is eroded, giving the stone a smooth surface” Stones of Celtis integrifolia are “ovoid, slightly acute and characteristically covered with several longitudinal 203 veins and a reticulate network in between..... The relatively thin-walled stone bears one chamber with one seed” as described by Neumann et al. (1998, p.61). The average diameter of stones in the reference collection is 7 mm. Verbenaceae Vitex simplicifolia Oliv. Number of specimens: 10 in 7 levels (Fig. 5, no. 9; and 11, no. 39). Half stones or nearly complete stones are all (except one in sample 27) flattened like extant V. simplicifolia and show a pear-like outline compared with fruit stones of other Vitex species. In cross section of the wall the vesicles can be seen which are characteristic of Vitex and allow the identification of many broken pieces as Vitex sp. Most probably, the pieces of the epidermis of a fleshy fruit also derive from Vitex sp. and are therefore listed in the table as cf. Vitex sp. epidermis fragments. Measurements: 7.66.55.5 mm Vitex sp. fruit stones are described by Neumann, et al. (1998, p 61 and Fig. 2, no. 2). Twelve species are mentioned in the Flora of West Tropical Africa, of which five are reported for northern Nigeria: V. thyrsiflora in forests, V. doniana in savannah woodland and open country, V. madiensis in savannah areas, V. simplicifolia (syn. V. diversifolia) in savannah and V. chrysocarpa on banks of rivers. The reference collection in Frankfurt contains the fruits of V. doniana, V. madiensis and V. simplicifolia. The shape of the cross section of the stones of V. doniana and V. madiensis is more or less a circle, only V. simplicifolia is obovate. Again only the stones of V. simplicifolia are a little flattened and pear-shaped in outline. The seeds have a smooth surface and resemble apple seeds in size. The inner chamber of the stone bears exactly the shape of the seed like an imprint. Vitex sp. (fragments). Number of specimens: 964 fragments in 23 levels. Vitex sp. (pieces of epidermis). Number of specimens: 99 in 16 levels Catalogue of unknown morphological types of seeds and fruits Some unidentified seeds were grouped into types with similar morphological characteristics. KUR-1 type. Number of specimens: 644 in 26 levels (Figs. 5, no. 34 and 11, nos. 11). Spherical to cylindrical seeds, most of them with a hole at the base and characteristic faintly longitudinal rims on the surface, which are sometimes underlain by transverse rims. The length varies from 0.6 to 1.8 mm length. KUR-2 type. Number of specimens: 10 in 6 levels (Figs. 5, no. 35 and 11, no. 7). Spherical to slightly elongated seeds with smooth surface, conspicuously spiny all over the surface. Measurements: 0.90.7 mm, broken, 1.00.8 mm, broken KUR-3 type. Number of specimens: 19 in 8 levels (Fig. 11, no. 5). Trigonous seeds which remind of Polygonaceae or Carex fruits. Measurements: sample 26:1.51.51.0 mm KUR-4 type. Number of specimens: 10 in 6 levels Trigonous small seeds, oblong, at the base faintly narrowed, surface smooth, one wall convex and a little bit broader than the other two, which are concave towards the base resembling European small Lamiaceae nutlets with less than 1 mm length. Measurements: sample 1:0.70.4 mm, apex and base truncated, three walls have equal size, sample 13:0.8 0.30.25 with a distinct acute base, sample 18:0.70.4 0.4 mm, 0.80.40.35 mm, sample 26:0.80.40.3 mm with an acute base, 0.70.250.3 mm, base broken, 0.60.250.28 mm, base truncate, 0.5 x 0.250.25 mm, base truncate. KUR-5 type. Unidentified fragments of fruit stones. Number of specimens: 512 fragments in 24 levels. This fragments may belong to Ziziphus sp., Celtis sp., Balanites sp., Kigelia sp. or others and make 14% of all charred remains counted. KUR-6 type. Number of specimens: 1 (Figs. 5, nos. 36 and 37 and 11, no. 10). Obovate seed or fruit with parallel sides, winged around both margins. Surface wrinkled with deep depressions near the wing. Measurements: 1.20.80.4 mm Indeterminata. Number of specimens: 655 in 25 levels. Mostly fragments of fruits and seeds which could not be identified. Acknowledgements We want to thank Krystyna Wasylikowa for personal discussions which were very helpful in finding out identification features, Katharina Neumann and Stefanie Kahlheber, Frankfurt, for fruitful discussions and critical reading of the manuscript and Richard J. Byer, Frankfurt, for correcting the English. Many thanks to Manfred Bsler of the Herbarium of the Botanischer Garten and Botanisches Museum Berlin-Dahlem, to Urs M. Weber, Basel, for photographs, Monika Heckner, Barbara Voss and Dirk Uebel, Frankfurt, for drawings. 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