A peer-reviewed open-access journal PhytoKeys 194: 123–133 (2022) doi: 10.3897/phytokeys.194.80967 RESEARCH ARTICLE https://phytokeys.pensoft.net Launched to accelerate biodiversity research A phylogeny of the Triraphideae including Habrochloa and Nematopoa (Poaceae, Chloridoideae) Paul M. Peterson1, Konstantin Romaschenko1, Yolanda Herrera Arrieta2 1 Department of Botany MRC-166, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013-7012, USA 2 Instituto Politécnico Nacional, CIIDIR Unidad Durango-COFAA, Durango, C.P. 34220, Mexico Corresponding author: Paul M. Peterson (peterson@si.edu) Academic editor: Clifford Morden | Received 21 January 2022 | Accepted 21 March 2022 | Published 18 April 2022 Citation: Peterson PM, Romaschenko K, Herrera Arrieta Y (2022) A phylogeny of the Triraphideae including Habrochloa and Nematopoa (Poaceae, Chloridoideae). PhytoKeys 194: 123–133. https://doi.org/10.3897/phytokeys.194.80967 Abstract To investigate the evolutionary relationships among species of the tribe Triraphideae (including two monotypic genera, Habrochloa and Nematopoa), we generated a phylogeny based on DNA sequences from nuclear ribosomal (ITS) and four plastid markers (rps16-trnK, rps16 intron, rpl32-trnL, and ndhA intron). Habrochloa and Nematopoa form a clade that is sister to Neyraudia and Triraphis. Member of the Triraphideae have paniculate inflorescences, 3-veined, marginally ciliate lemmas, usually with hairy lateral veins, that are apically bifid and awned from between a sinus. A description of the Triraphideae and key to the genera is provided, and the biogeography is discussed, likely originating in Africa. Keywords Classification, Habrochloa, molecular phylogenetics, Nematopoa, Neyraudia, Triraphideae, Triraphis Introduction Clayton and Renvoize (1986) pointed out that Neyraudia R. Br. was perhaps an ally of Triraphis R. Br. since both genera possess slender microhairs and the two have keeled lemmas that are villous on the lateral veins (Watson and Dallwitz 1992). Based on DNA sequence studies Bouchenak-Khelladi et al. (2008) were first to show strong support for Neyraudia and Triraphis as being sister in the subfamily Chloridoideae Kunth ex Beilschm. Hilu and Alice (2001) and Bouchenak-Khelladi et al. Copyright Paul M. Peterson et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 124 Paul M. Peterson et al. / PhytoKeys 194: 123–133 (2022) (2008), using the same matK sequence marker placed these two genera in the subtribe Uniolinae Clayton, now a member of tribe Eragrostideae Stapf. Another DNA sequence study supported the placement of the Neyraudia–Triraphis clade as being sister to remaining species in the Chloridoideae and, subsequently, the tribe Triraphideae P.M. Peterson [based on subtribe Triraphidinae Stapf (1917)] was erected to include these two genera (Peterson et al. 2010). Using unpublished DNA sequence phylogenies (Peterson and Romaschenko, unpubl.), the monotypic Habrochloa C.E. Hubb., was added to the Triraphideae in the classification of all genera within the Poaceae (Soreng et al. 2015, 2017). Hubbard (1935, 1957a, b) transferred Triraphis longipes Stapf & C.E. Hubb. to Crinipes Hochst. (Arundinoideae) since it possessed a bearded callus, then later moved it to a new monotypic genus, Nematopoa C.E. Hubb. Nematopoa was included in the Arundinoideae by Clayton and Renvoize (1986). In more recent classifications (Soreng et al. 2015, 2017), Nematopoa longipes (Stapf & C.E. Hubb.) C.E. Hubb. was placed as a synonym of Triraphis as originally described. Based on unpublished DNA sequence phylogenies (Peterson and Romaschenko, unpubl.), Soreng et al. (2022) and Gallaher et al. (2022) placed Nematopoa in the Triraphideae. Therefore, the current concept of the Triraphideae consists of four genera, Habrochloa, Nematopoa, Neyraudia, and Triraphis. Habrochloa bullockii C.E. Hubb. is a small, delicate, African annual (culms 10– 25 cm tall) with a fringe of hairs for a ligule and delicate panicles bearing 3–5-flowered spikelets, each including awned, apically bifid, marginally ciliate lemmas that bear trigonous caryopses, whereas Nematopoa longipes is a caespitose, southern African perennial (culms 30–80 cm tall) with ciliate, membranous ligules and capillary panicles bearing 4–7-flowered spikelets, each including awned, apically bifid, marginally ciliate lemmas (Clayton et al. 2016). Neyraudia consists of four reedlike perennials [culms (0.8–) 1–5 m tall], a cartilaginous ridge with a line of hairs apically for a ligule, and plumose panicles bearing 3–8-flowered spikelets, each including awned, apically bifid lemmas that are ciliate marginally and along lateral veins; three species in tropical and temperate Asia and one species in Africa (Watson et al. 1992; Filgueiras and Zuloaga 1999; Guala 2003; Clayton et al. 2016). Triraphis consists of eight annual or perennials (culms 4−140 cm tall) with membranous ligules or a fringe of hairs and open or contracted (rarely spiciform) panicles bearing 4−24-flowered spikelets, each including apically 3-lobed and 3-awned lemmas that are ciliate marginally and villous along the lateral veins, and trigonous caryopses; six species in Africa, one in Australasia and one in South America (Watson et al. 1992; Nightingale and Weiller 2005; Clayton et al. 2016). In the present phylogenetic study, using DNA sequences from nuclear ribosomal (ITS) and four plastid markers (rps16-trnK, rps16 intron, rpl32-trnL, and ndhA intron), we include for the first time Habrochloa bullockii, Nematopoa longipes, and Neyraudia arundinacea (L.) Henrard with two other species of Neyraudia and five species of Triraphis. In addition, we include a description of the Triraphideae, key to the genera in the tribe, and hypothesize its biogeographical history. Phylogeny of the Triraphideae 125 Materials and methods Detailed methods for DNA extraction, amplification, and sequencing are given in Romaschenko et al. (2012) and Peterson et al. (2010, 2014a, b, 2015a, b, 2016). We used Geneious Prime 2020 (Kearse et al. 2012) for contig assembly of bidirectional sequences of ndhA intron, rpl32-trnL, rps16 intron, rps16-trnK and ITS regions, and implemented in Geneious Muscle algorithm (Edgar 2004) to align the sequences and adjust the final alignment. The maximum likelihood parameters for each region were estimated with GARLI 2.0 (Zwickl 2006) and were used as priors in Bayesian calculations to infer overall phylogeny. The Bayesian tree was constructed using MrBayes v3.2.7 (Huelsenbeck and Ronquist 2001; Ronquist et al. 2012). All compatible branches were saved. The Bayesian analysis was initiated with random starting trees sampling once per 100 generations and continued until the value of the standard deviation of split sequences dropped below 0.01 indicating convergence of the chains. The effective sample size (ESS) value for all the parameters was greater than 200 and the first 25% of the sampled values were discarded. Maximum likelihood bootstrap analyses (Felsenstein 1985) were performed using GARLI with 1000 repetitions. The resulted file containing 1000 trees from the bootstrap analysis was then read into PAUP* v.5.0 (Swofford 2000) to compute the majority rule consensus tree. Our study was designed to test relationships among species residing in four genera (Habrochloa, Nematopoa, Neyraudia, and Triraphis) attributed to the Triraphideae. Representative species from all remaining tribes (Centropodieae P.M. Peterson, N.P. Barker & H.P. Linder, Cynodonteae Dumort., Eragrostideae Stapf, and Zoysieae Benth.) in the Chloridoideae have been included to test the monophyly of the tribe (Peterson et al. 2010). In addition, the phylogeny includes two species from the Danthonioideae, Danthonia compressa Austin and Merxmuellera drakensbergensis (Schweick.) Conert, and one species from the Panicoideae, Chasmanthium latifolium (Michx.) H.O. Yates, which was used as an outgroup. Results and discussion Thirty-five new sequences (16%) from five species (nine individuals) are newly reported in GenBank, along with all other sequences for 48 individuals and 41 species included in this study (Table 1). Total aligned characters, numbers of sequences, proportion of invariable sites, and other parameters are noted in Table 2. The resulting plastid and ITS topologies were inspected for conflicting nodes with ≥ 95% posterior probabilities. No supported conflict was found so plastid and ITS sequences were combined. The Bayesian tree from the combined plastid and ITS regions is well resolved (Fig. 1). Most clades have posterior probabilities equal to 1.00 and additional bootstrap values of 90% or greater. There is strong support for Habrochloa bullockii + Nematopoa longipes sister to a monophyletic Neyraudia with three individuals of N. reynaudiana (Kunth) Keng ex Hitchc. sister to one individual of N. arundinacea (type of the genus) Voucher Country 1 2 3 4 5 Centropodia glauca (Nees) Cope Centropodia mossamedensis (Rendle) Cope Chasmanthium latifolium (Michx.) H.O. Yates Chloris barbata Sw. Cottea pappophoroides Kunth South Africa South Africa USA, Maryland Mexico, Sinaloa Peru, Ancash JF729075 JF729076 GU360517 GU360514 GU360600 – JF729182 GU360438 GU360435 GU360456 JF729175 JF729176 GU359891 GU359873 GU359842 6 7 8 9 Danthonia compressa Austin Eleusine indica (L.) Gaetrn. Eleusine poiflora (Chiov.) Chiov. Ellisochloa rangei (Pilg.) P.M. Peterson & N.P. Barker Enneapogon scaber Lehm. Entoplocamia aristulata (Hack. & Rendle) Stapf Eragrostis kennedyae F. Turner Eragrostis wiseana (C.A. Gardner & C.E. Hubb.) R.L. Barrett & P.M. Peterson Gouinia virgata var. robusta J.J. Ortíz Gymnopogon grandiflorus Roseng., B.R. Arill. & Izag. Habrochloa bullockii C.E. Hubb. Davidse 6367 (US) Schweickerdt 2250 (US) Peterson 22463 (US) Peterson 22255& Saarela (US) Peterson 21463, Soreng, LaTorre & Rojas Fox (US) Peterson 21986 & Levine (US) Peterson 21362, Saarela & Flores Villegas (US) Burger 2915 (US) Barker 960 (BOL) ndhA ITS intron JF729164 JF729164 – – GU359379 GU359319 GU359377 GU359320 GU359363 GU359237 USA, North Carolina Mexico, Mexico Ethiopia Namibia GU360521 GU360496 GU360601 JF729079 GU360483 GU360472 GU360457 JF729184 GU359865 GU359797 GU359843 – GU359370 GU359345 GU359473 GU359338 – GU359236 JF729166 JQ345167 Sachse 008 (MO) Seydel 187 (US) Latz 13486 (MO) Peterson 14345, Soreng & Rosenberg (US) South Africa, Western Cape South Africa Australia Australia, Western Australia JQ345237 GU360492 JQ345238 GU360703 JQ345279 GU360468 JQ345281 GU360288 JQ345322 GU359793 JQ345323 GU359986 JQ345208 JQ345168 GU359469 GU359342 JQ345209 JQ345169 GU359533 GU359137 Reeder 4714 & Reeder (US) Peterson 16642 & Refulio-Rodriguez (US) Mexico, Zacatecas Peru, Apurimac KF827775 GU360581 KF827710 GU360383 KF827639 GU359816 KF827584 KF827521 GU359436 GU359200 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Leptocarydion vulpiastrum (De Not.) Stapf Leptochloa digitata (R.Br.) Domin Leptothrium senegalense (Kunth) Clayton Merxmuellera drakensbergensis (Schweikerdt) Conert Monelytrum luederitzianum Hack. Mosdenia leptostachys (Ficalho & Hiern) Clayton Muhlenbergia japonica Steud. Peterson 23927b, Soreng, Romaschenko & Tanzania, Ruvuma Abeid (US) Peterson 24238, Soreng & Romaschenko (US) Tanzania Risler 476 & Kerrigan (MO) Australia, Northern Territory Belsky 336 (MO) Kenya Mafa 4 (GRA) South Africa Smook 10031 (US) Schweickerdt 1542 (US) Soreng 5240, Peterson & Sun Hang (US) South Africa South Africa China, Yunnan rps16-trnK rps16 intron rpl32-trnL ON012448 ON012442 ON012427 ON012435 OM980631 KF827792 JQ345246 KF827795 JF729078 KF827660 JQ345331 KF827663 – KF827725 JQ345289 KF827728 JF729183 KF827595 JQ345213 KF827597 JF729165 KF827539 JQ345178 KF827542 – GU360682 GU360421 GU359969 GU359459 GU359158 GU360681 GU360420 GU359967 GU359458 GU359159 HM143667 HM143571 HM143183 HM143388 HM143081 Paul M. Peterson et al. / PhytoKeys 194: 123–133 (2022) Taxon 126 Table 1. Taxon voucher (collector, number, and where the specimen is housed), country of origin, and GenBank accession for DNA sequences of rps16-trnK, rps16 intron, rpl32-trnL, ndhA intron, and ITS regions; bold indicates new accession; a dash (–) indicates missing data, an asterisk (*) indicates sequences not generated in our lab. 24 25 26 27 28 29 30 41 42 43 Country Neesiochloa barbata (Nees) Pilg. Nematopoa longipes (Stapf & C.E. Hubb.) C.E. Hubb. Neyraudia arundinacea (L.) Henrard Swallen 4491 (US) Simon 2353 Brazil Africa Peterson 23991, Soreng, Romaschenko & Abeid (US) Neyraudia reynaudiana (Kunth) Keng ex Hitchc. Columbus 5302 (RSA) Neyraudia reynaudiana (Kunth) Keng ex Hitchc. Soreng 5318, Peterson & Sun Hang (US) Neyraudia reynaudiana (Kunth) Keng ex Hitchc. Srisanga 97923, Norsaengsri, Unwin, Rodda, Schuettpelz, Tin Tin Mu & Ling Shein Man (US) Pappophorum pappiferum (Lam.) Kuntze Peterson 21689, Soreng, La Torre & Rojas Fox (US) Perotis indica (L.) Kuntze Peterson 23880, Soreng & Romaschenko (US) Psilolemma jaegeri (Pilg.) S.M. Phillips Peterson 24247, Soreng & Romaschenko (US) Sporobolus virginicus (L.) Kunth Peterson 15683 & Soreng (US) Tragus berteronianus Schult. FLSP 457 (US) Tridens flavus var. chapmanii (Small) Shinners McCauley 438 (MO) Triplasis americana P. Beauv. Kral 12065 (MO) Triraphis andropogonoides (Steud.) E. Phillips Mennell s.n. (US) Triraphis mollis R. Br. Lazarides 046 & Palmer (US) Triraphis mollis R. Br. Peterson 14344, Soreng & Rosenberg (US) Triraphis mollis R. Br. Saarela 1608, Peterson, Soreng & Judziewicz (US) Triraphis mollis R. Br. Saarela 1615, Peterson, Soreng & Judziewicz (US) Triraphis mollis R. Br. Saarela 1648, Peterson, Soreng & Judziewicz (US) Triraphis mollis R. Br. Saarela 1656, Peterson, Soreng & Judziewicz (US) Triraphis purpurea Hack. Schweickerdt 2115 (US) Triraphis ramosissima Hack. Seydel 4278 (US) Triraphis schinzii Hack. Smook 1933 (US) Uniola condensata Hitchc. Peterson 9342 & Judziewicz (US) Zoysia macrantha subsp. walshii M.E. Nightingale Loch 435 (US) rps16-trnK rps16 intron rpl32-trnL ndhA ITS intron GU360724 GU360279 GU360005 – GU359122 MF035992* MF035992* MF035992* MF035992* – Tanzania, Njomba ON012449 ON012443 ON012428 ON012436 OM980632 China, Yunnan China, Myanmar KF356392* KF356392* GU360272 – – – KF356392* KF356392* – GU360003 GU359397 GU359124 ON012429 – OM980633 GU360700 GU360276 GU359996 GU359402 GU359128 Tanzania Tanzania Chile, Region I Peru USA, Missouri USA, Georgia South Africa, Cape Province Australia, Uluru National Park Australia, Western Australia Australia, Northern Territory KF827801 KF827734 KM011122 KM010919 GU360610 GU360362 GU360616 GU360370 KF827817 KF827751 KF827818 KF827752 GU360654 GU360335 – – GU360669 GU360336 ON012450 ON012444 KF827669 KM010695 GU359892 GU359898 KF827689 KF827690 GU359949 ON012430 GU359933 ON012431 KF827601 KM010535 GU359502 GU359503 KF827615 KF827616 ON012437 – GU359539 ON012438 Australia, Northern Territory ON012451 ON012445 ON012432 ON012439 OM980636 Australia, Northern Territory ON012452 ON012446 ON012433 ON012440 OM980637 Australia, Northern Territory ON012453 ON012447 ON012434 ON012441 OM980638 GU360652 GU360651 GU360650 GU360649 GU360642 GU359932 GU359931 GU359930 GU359927 GU359922 Peru, Ancash Namibia Namibia South Africa Ecuador, Chimborazo Australia GU360337 GU360338 GU360339 GU360340 GU360345 KF827546 KM010326 GU359215 GU359224 KF827568 KJ768887 – OM980634 GU359187 OM980635 GU359549 – GU359541 GU359188 – – GU359534 GU359191 GU359548 GU359197 127 44 45 46 47 48 Voucher Phylogeny of the Triraphideae 31 32 33 34 35 36 37 38 39 40 Taxon 128 Paul M. Peterson et al. / PhytoKeys 194: 123–133 (2022) plus a monophyletic Triraphis. The Triraphis clade includes six individuals of T. mollis R. Br. (type of the genus as treated by Burbidge 1946 and Peterson et al. 2022) sister to T. schinzii Hack. and T. ramosissima Hack. sister to T. andropogonoides (Steud.) E. Phillips + T. purpurea Hack. Our molecular data clearly support independent recognition of Nematopoa since it is sister to Habrochloa and not a member of the Triraphis clade. Habrochloa bullockii and Nematopoa longipes are clearly aligned within the Triraphideae, and together with Neyraudia and Triraphis, share the following salient morphological features: paniculate inflorescences, 3-veined, marginally ciliate lemmas, usually with hairy lateral veins, and lemmas that are apically bifid and awned from between the sinus (Watson and Dallwitz 1992; Watson et al. 1992; Peterson et al. 2010; Clayton et al. 2016). Another probable synapomorphy for these four genera is possession of panicoid-type bicellular microhairs (long, narrow basal and terminal cells; Amarasinghe and Watson 1988). Watson et al. (1992) verified the presence of panicoid bicellular microhairs for Habrochloa, Nematopoa, and Triraphis but indicate that they are absent in Neyraudia arundinacea. However, Clayton and Renvoize (1986) previously indicated that Neyraudia possesses slender microhairs similar to those in Triraphis. Based on a sample containing Nematopoa, Neyraudia, and Triraphis, Gallaher et al. (2022) determined the crown age (10.62 Ma) and stem age (46.76 Ma) of the Triraphideae. Although at least three species of Neyraudia include tropical and temperate Asia in their distribution, Africa is the most likely area of origin for the Triraphideae since all four genera in the tribe include species distributed in Africa. In addition, the Triraphideae shares a common ancestor with Centropodieae, also from Africa and temperate Asia (Peterson et al. 2011). Because more than half of the genera of Chloridoideae reside in Africa and the larger tribes, i.e., the Eragrostideae Table 2. Characteristics of the five DNA regions (rps16-trnK, rps16 intron, rpl32-trnL, ndhA and ITS) and parameters used as priors in Bayesian analyses estimated with GARLI. 2.0. Characteristic Total aligned characters Number of sequences Number of new sequences rps16-trnK rps16 intron rpl32-trnL ndhA intron Combined plastid data ITS Overall 887 1046 844 1146 3923 769 4692 45 45 46 42 178 41 219 6 (13%) 6 (13%) 8 (17%) 7 (17%) 27 (15%) 8 (20%) 35 (16%) Likelihood score (-lnL) 3909.0 3405.6 3778.7 4281.4 7973.0 Number of substitution types 6 6 6 6 Model for among-sites rate variation gamma Gamma gamma gamma Substitution rates 1.2071 1.2951 1.0625 0.9848 – 1.1422 2.7093 1.2876 1.7914 2.5216 2.6273 0.4083 0.3028 0.3251 0.2912 1.7222 1.5405 1.1547 1.4401 1.9389 0.6568 2.9778 2.0746 1.5146 2.3679 4.5253 1.0000 1.0000 1.0000 1.0000 1.0000 Character state frequencies 0.3088 0.3779 0.3693 0.3669 – 0.2404 0.1363 0.1226 0.1380 0.1348 0.2374 0.1462 0.1743 0.1222 0.1484 0.2582 0.4084 0.3251 0.3703 0.3497 0.2641 Proportion of invariable sites 0.1666 0.3154 0.0413 0.2537 – 0.2547 Gamma shape parameter (α) 2.1848 1.0833 0.9498 1.0636 – 0.9409 Phylogeny of the Triraphideae 129 Chasmanthium latifolium (outgroup) DAN Danthonia compressa .86 86 Merxmuellera drakensbergensis Ellisochloa rangei CEN Centropodia glauca Centropodia mossamedensis Habrochloa bullockii Nematopoa longipes Neyraudia arundinacea Neyraudia reynaudiana Soreng 5318 Neyraudia reynaudiana Columbus 5302 Neyraudia reynaudiana Srisanga 97923 Triraphis ramosissima Triraphis andropogonoides Triraphis purpurea Triraphis schinzii Triraphis mollis Saarela 1615 Triraphis mollis Peterson 14344 Triraphis mollis Saarela 1608 Triraphis mollis Lazarides 046 Triraphis mollis Saarela 1648 .84 Triraphis mollis Saarela 1656 .59 1 81 TRI * .76 50 1 86 ERA ZOY .75 74 1 75 CYN NA 1 56 SA Africa Australia Eastern Asia (China, Mongolia, Japan, India) 0.02 Cottea pappophoroides Enneapogon scaber Entoplocamia aristulata Uniola condensata Eragrostis kennedyae Eragrostis wiseana Zoysia macrantha ssp. walshii Psilolemma jaegeri Sporobolus virginicus Muhlenbergia japonica Monelytrum luederitzianum Tragus berteronianus Neesiochloa barbata Pappophorum pappiferum Tridens flavus var. chapmanii Chloris barbata Leptochloa digitata Eleusine poiflora Eleusine indica Gouinia virgata var. robusta Triplasis americana Mosdenia leptostachys Perotis indica Leptothrium senegalense 1 Gymnopogon grandiflorus 82 Leptocarydion vulpiastrum Figure 1. Maximum-likelihood tree inferred from combined plastid (rps16-trnK, rps16 intron, rpl32trnL, and ndhA intron) and ITS sequences. Numbers above branches are posterior probabilities; numbers below branches are bootstrap values; thick branches indicate bootstrap ≥ 90% and posterior probabilities of 1.00; DAN = Danthonioideae; tribes within the Chloridoideae = *, include: CEN = Centropodieae, TRI = Triraphideae, ERA = Eragrostideae, ZOY = Zoysieae, and CYN = Cynodonteae. Scale bar: 2%. and Zoysieae have centers of diversity there, Hartley and Slater (1960) earlier concluded that the subfamily probably originated on the African continent and spread to other parts of the world (Bouchenak-Khelladi et al. 2008; Peterson et al. 2007, 2010, 2011, 2014c). 130 Paul M. Peterson et al. / PhytoKeys 194: 123–133 (2022) Taxonomy Triraphideae P.M. Peterson, Molec. Phylogen. Evol. 55(2): 591. 2010 ≡ Triraphidinae Stapf, Fl. Trop. Afr. 9: 22. 1917 – Type: Triraphis R. Br., Prodr. 185. 1810. Description (emendation). Annuals or perennials, sometimes rhizomatous or reedlike (Neyraudia) culms 4–500 cm tall, erect or decumbent; ligules membranous and ciliate or a fringe of hairs; inflorescence a panicle, open to contracted, rarely spiciform; spikelets 2–15 mm long, 3–24-flowered, laterally compressed; glumes usually shorter than the spikelets or upper glume 2 × as long as adjacent lemma (Habrochloa), 0-, 1- or 3-veined, membranous, sometimes hyaline, apex entire to mucronate, rarely awned; lemmas membranous, rarely cartilaginous, 3-veined with ciliate or pilose margins, lateral veins, if present, usually hairy and sometimes extending as awns (Triraphis), apex bifid and awned from between the sinus; paleas 0.5 to as long as lemma, 2-veined; stamens 3; caryopses with adherent pericarp, often trigonous to ellipsoid, sometimes linear. Included genera. Habrochloa, Nematopoa, Neyraudia, Triraphis. Key to the genera 1 – 2 – 3 – Lemmas 3-awned, the lateral veins extending into awns.................Triraphis Lemmas 1-awned, the lateral veins never extending into awns ....................2 Culms (80–) 100–500 cm tall, generally 1–1.5 cm wide at base, often woody; plants perennial, reedlike; ligules cartilaginous at base, apically with a line of hairs; panicles 30–80 cm long, plumose .......................................Neyraudia Culms 10–80 cm tall, ≤ 3 mm wide at base, herbaceous; plants annual not reedlike; ligules membranous with a fringe of hairs, not cartilaginous at base; panicles 2–30 cm long, not plumose ...........................................................3 Spikelets 2–2.5 mm long; lemmas 1–1.3 mm long, 3-veined, awned, the awns 4–6 mm long; upper glumes 2 × as long as adjacent lemma ................. ..................................................................................................Habrochloa Spikelets 6–10 mm long; lemmas 3.5–4.3 mm long, 1-veined, awned, the awns 8–13 mm long; upper glumes 0.5–0.6 × as long as adjacent lemma ..... .................................................................................................. Nematopoa Acknowledgements We thank the National Geographic Society Committee for Research and Exploration (Grant No. 8848-10, 8087-06) for field and laboratory support; the Smithsonian Institution’s Restricted Endowments Fund, the Scholarly Studies Program, Research Opportunities, Atherton Seidell Foundation, Biodiversity Surveys and Inventories Program, Small Grants Program, the Laboratory of Analytical Biology, and the United States Department of Agriculture. We thank Neil Snow, Clifford W. Morden, and Ana Isabel Honfi for suggesting changes to the manuscript. Phylogeny of the Triraphideae 131 References Amarasinghe V, Watson L (1988) Comparative ultrastructure of microhairs in grasses. 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