The Families of Angiosperms

L. Watson and M.J. Dallwitz

Cyperaceae Juss.

Including Kobresiaceae Gilly, Lepistichaceae Dulac, Scirpaceae Burnett

Habit and leaf form. Herbs. ‘Normal’ plants, or switch-plants (sometimes elaminate); sometimes with the principal photosynthesizing function transferred to stems. Annual, or biennial, or perennial; with a basal aggregation of leaves (usually), or without conspicuous aggregations of leaves. Young stems not breaking easily at the nodes. (0.005–)0.05–3(–5) m high; rhizomatous, or tuberous. Hydrophytic, or helophytic, or mesophytic, or xerophytic (rarely, e.g. Caustis); when hydrophytic, free floating, or rooted. Leaves of aquatics submerged and emergent. Leaves alternate; spiral (rarely), or distichous (often), or tristichous (usually); flat, or folded (and occasionally plicate), or rolled, or terete; ‘herbaceous’, or leathery; sessile, or petiolate (occasionally); sheathing. Leaf sheaths with joined margins (usually), or with free margins. Leaves with blades borne edgewise to the stem, or with blades ‘normally orientated’; simple. Lamina entire; setaceous, or acicular, or linear to obovate; parallel-veined; cross-venulate, or without cross-venules. Leaves ligulate (commonly), or eligulate. Lamina margins usually entire (but commonly with prickle hairs); flat, or revolute, or involute. Prophylls 1. Leaf development ‘graminaceous’. Vernation conduplicate, or plicate, or involute, or revolute, or convolute.

General anatomy. Plants with silica bodies (usually). Chlorenchyma including ‘peg cells’ (if ‘lobed cells’ (Metcalfe 1971) be so interpreted), or without ‘peg cells’ (if not).

Leaf anatomy. The leaf lamina dorsiventral, or bifacial, or centric. Epidermis without differentiation into ‘long’ and ‘short’ cells; containing silica bodies (usually), or without silica bodies. Stomata present; usually paracytic. The mesophyll not containing mucilage cells; without crystals (or very rare(?), and raphides absent). Foliar vessels present; with scalariform end-walls, or with simple end-wall perforations, or with scalariform end-walls and with simple end-wall perforations. Minor leaf veins without phloem transfer cells (Cyperus, Eriophorum, Eleocharis).

Axial (stem, wood) anatomy. Young stems triangular in section (commonly), or cylindrical, or oval in section, or flattened; with solid internodes to with spongy internodes, or with hollow internodes (uncommonly). Cork cambium absent. Secondary thickening absent (with compound vascular bundles in Gahnia).

The vessel end-walls scalariform, or simple, or scalariform and simple.

Root anatomy. Root xylem with vessels; vessel end-walls scalariform, or simple, or scalariform and simple.

Reproductive type, pollination. Unisexual flowers present, or absent. Plants hermaphrodite, or monoecious, or andromonoecious, or gynomonoecious, or dioecious, or androdioecious, or gynodioecious. Floral nectaries absent (nectaries lacking). Pollination anemophilous (mostly), or entomophilous (occasionally, associated with white or coloured bracts or upper leaves).

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in ‘spikelets’. The ultimate inflorescence units cymose, or racemose (the flowers solitary, or 1–50 in ‘spikelets’). Inflorescences with the spikelets often numerous, in branched, paniculate inflorescences. Flowers bracteate, or ebracteate; bracteolate (each borne in the axil of a ‘glume’); usually small, or minute. Perigone tube absent. Hypogynous disk absent (usually), or present (in a few genera).

Perianth of ‘tepals’, or vestigial (represented by bristles or hairs), or absent; when present, often 6; free; sometimes more or less sepaloid.

Androecium 1–3, or 4–6(–22). Androecial members free of the perianth; free of one another (usually), or coherent (connate filaments in some Carex species). Androecium exclusively of fertile stamens. Stamens 1–3, or 4–6(–22). Anthers basifixed; introrse, or latrorse; tetrasporangiate; appendaged (via prolongation of the connective into an apiculus), or unappendaged. Endothecium developing fibrous thickenings. The endothecial thickenings spiral (consistently so in a sample of 30 genera, Bruhl 1990). Anther epidermis persistent. Microsporogenesis simultaneous (specialised, ‘cyperaceous type’). The initial microspore tetrads undergoing degeneration, resulting in a pseudomonad. Anther wall initially with one middle layer; of the ‘monocot’ type. Tapetum glandular. Pollen shed in aggregates (though ostensibly solitary, as pseudomonads); in tetrads (with three members degenerated). Pollen grains aperturate; 1–4(–15) aperturate; ulcerate, or porate, or ulcerate and porate, or foraminate (usually with a single ulcoid aperture, but often with a ring of transverse lateral lacunae, rarely with four ill-defined foramina). The ulcus when ulcerate, without an operculum; without an annulus. Interapertural interstitium columellate. Pollen grains 2-celled (Fimbristylis, Scirpus), or 3-celled (Carex, Cyperus, Eleocharis, Rhynchospora, Schoenoplectus).

Gynoecium 2 carpelled, or 3(–4) carpelled. The pistil 1 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary 1 locular. Styles 2–3; free to partially joined. Stigmas (1–)2, or 3(–15); dry type; papillate, or non-papillate; Group II type (IIA and IIB). Placentation basal. Ovules in the single cavity 1; non-arillate; anatropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids hooked. Hypostase present, or absent. Endosperm formation nuclear. Embryogeny onagrad.

Fruit non-fleshy; indehiscent; achene-like, or a drupe (very rarely). The drupes with one stone. Fruit 1 seeded. Seeds endospermic. Endosperm not oily (mealy or fleshy, usually), or oily (rarely). Seeds usually with starch. Embryo well differentiated, or rudimentary at the time of seed release (Rhynchosporoideae). Cotyledons when detectable, 1. Embryo achlorophyllous (doubtfully — 2/2). Testa without phytomelan.

Seedling. Hypocotyl internode absent. Mesocotyl present (e.g. Isolepis), or absent. Seedling collar not conspicuous. Cotyledon hyperphyll compact; non-assimilatory. Coleoptile present. Seedling cataphylls absent. First leaf dorsiventral. Primary root ephemeral.

Physiology, phytochemistry. C₃, or C₄, or C₃-C₄ intermediate. C₃ physiology recorded directly in 103 genera: see Bruhl database. C₄ physiology recorded directly in 27 genera: see Bruhl database. C₃-C₄ intermediacy in Eleocharis spp. Anatomy C₄ type (27 genera), or non-C₄ type (103 genera). Accumulated starch exclusively ‘pteridophyte type’. Not cyanogenic. Alkaloids present (occasionally, simple indole), or absent. Saponins/sapogenins absent. Proanthocyanidins present (more commonly, and more abundantly, than in Gramineae), or absent; when present, cyanidin (usually), or cyanidin and delphinidin (Isolepis). Flavonols present (more commonly than in Gramineae), or absent; quercetin. Ellagic acid absent. Aluminium accumulation demonstrated. Sieve-tube plastids P-type; type II.

Geography, cytology. Holarctic, Paleotropical, Neotropical, Cape, Australian, and Antarctic. Frigid zone to tropical. Cosmopolitan, predominating in moist habitats. Chromosomes with diffuse centromeres.

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Commeliniflorae; Cyperales. APG III core angiosperms; Superorder Lilianae; commelinid Monocot. APG IV Order Poales.

Species about 5400. Genera about 110; Abildgaardia, Acriulus, Actinoschoenus, Afrotrilepis, Alinula, Androtrichum, Anosporum, Arthrostylis, Ascolepis, Ascopholis, Baeothryon, Baumea, Becquerelia, Bisboeckelera, Blysmopsis, Blysmus, Bolboschoenus, Bulbostylis, Calyptrocarya, Capitularina, Carex, Carpha, Caustis, Cephalocarpus, Chorizandra, Chrysitrix, Cladium, Coleochloa, Costularia, Courtoisina, Crosslandia, Cyathochaeta, Cyathocoma, Cymophyllus, Cyperus, Desmoschoenus, Didymiandrum, Diplacrum, Diplasia, Dulichium, Egleria, Eleocharis, Eleogiton, Epischoenus, Eriophoropsis, Eriophorum, Erioscirpus, Evandra, Everardia, Exocarya, Exochogyne, Ficinia, Fimbristylis, Fuirena, Gahnia, Gymnoschoenus, Hellmuthia, Hemicarpha, Hymenochaeta, Hypolytrum, Isolepis, Kobresia, Kyllinga, Kyllingiella, Lagenocarpus, Lepidosperma, Lepironia, Lipocarpha, Lophoschoenus, Machaerina, Mapania, Mapaniopsis, Mariscus, Mesomelaena, Microdracoides, Micropapyrus, Monandrus, Morelotia, Neesenbeckia, Nemum, Nelmesia, Oreobolopsis, Oreobolus, Oxycaryum, Paramapania, Phylloscirpus, Pleurostachys, Principina, Pseudoschoenus, Ptilanthelium, Pycreus, Queenslandiella, Reedia, Remirea, Rhynchocladium, Rhynchospora, Rikliella, Schoenoplectus, Schoenoxiphium, Schoenoides, Schoenus, Scirpodendron, Scirpoides, Scirpus, Scleria, Sphaerocyperus, Sumatroscirpus, Syntrinema, Tetraria, Tetrariopsis, Thoracostachyum, Torulinium, Trachystylis, Trianoptiles, Trichoschoenus, Tricostularia, Trilepis, Tylocarya, Uncinia, Vesicarex, Volkiella, Websteria.

General remarks. Recent family treatments: Goetghebeur (1986); Bruhl (1995). For interactive identification and information retrieval, and comprehensive html generic descriptions, see J.J. Bruhl (1998), ‘Genera of Cyperaceae’, available online at https://www.delta-intkey.com/caes/index.htm.

Economic uses, etc. Some noxious weeds, otherwise of little economic importance — Cyperus papyrus is of historical interest in connection with papermaking, and that genus furnishes a few watergarden ornamentals; Cyperus esculentus has edible rhizomes.

Quotations.

Alas, poor hurt fowl; now will he creep into the sedges
(‘Much Ado’, ii., 1)

The gentle Severn’s sedgy bank
(‘1st Henry the Fourth’, i., 3)

You nymphs, called naiads, of the winding brooks,
With your sedged crowns, and ever-harmless looks
(‘Tempest’, iv., 1)

Nut-grass is not Grass
(anon)

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 25th April 2024. delta-intkey.com’.

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