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Published In: Genera Plantarum 26. 1789. (4 Aug 1789) (Gen. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 9/1/2009)
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CYPERACEAE (Sedge Family)

Plants annual or perennial, sometimes with rhizomes and/or tuberous thickenings, monoecious or with perfect flowers. Aerial stems circular in cross-section or often 3-angled. Leaves basal and/or alternate, often noticeably 3-ranked, grasslike, parallel-veined, the bases strongly sheathing, the sheaths almost always closed (fused around the stem all or most of the way to the summit), sometimes with a ligule on the inner (upper) surface at the tip, the leaf blades sometimes lacking or highly reduced. Basic units of inflorescences spikelets or spikes (see discussion in the introductory portion of the Carex treatment), these 1 to many, terminal and/or axillary (sometimes basal), arranged into panicles, headlike clusters, or umbels that are often subtended by 1 or more leaflike (or less commonly stemlike or scalelike) bracts. Individual flowers (florets) of a spikelet or spike subtended by scalelike bracts (referred to as scales by most botanists and in this treatment). Perianth absent or reduced to 1–6 (rarely more) bristles or small scales attached below the ovary. Stamens 1–3. Pistil 1, naked or enclosed in a saclike perigynium in Carex. Style 1, branched into 2–3 stigmas at the tip, sometimes persistent at the tip of the fruit as a beak of the same color and texture as the fruit, or as a conical or triangular tubercle that differs in texture and/or color from the main body of the fruit and is separated from it by a line or constriction. Ovule 1 per floret. Fruits achenes. Eighty to 115 genera, 3,500–4,500 species, worldwide.

The Cyperaceae are a large and taxonomically difficult family that still requires detailed taxonomic study on a worldwide basis. Generic limits for many of the groups are hotly debated by specialists, which has resulted in a confusing array of generic transfers in the literature, and often markedly different treatments of the same species groups in floristic manuals covering regions in North America, Europe, Africa, and elsewhere. The treatment below generally follows the generic classification of Bruhl (1995) and accepts many of the recent generic reassessments. However, Cyperus is treated in the relatively broad, traditional fashion (see the treatment of Cyperus for further discussion).

Determination of genus and species for a specimen in this family requires patience and detailed observations using a hand lens or dissecting microscope. Collectors should note that rootstocks and mature fruits usually are necessary for accurate determinations. Vegetative or flowering plants of Cyperaceae generally should be avoided. In a few cases, determinations are aided by observation of both fertile and vegetative shoots and their respective leaf arrangements.

The determination of annual vs. perennial growth form is important for keying plants of most genera of Cyperaceae, but this can be difficult to establish for some plants. In general, annual species have “soft bases” that can usually be pulled from the ground with their roots relatively intact and show no evidence of rhizomes, tuberous root thickenings, or previous years’ stem or leaf bases. Perennials have “hard bases” that are frequently (but not always) difficult to pull up with intact rootstocks, often have rhizomes, tuberous roots, or otherwise thickened rootstocks, and usually have remnants of previous years’ stem and/or leaf bases.


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1 Ovary or fruit enclosed in (but not fused to) a saclike perigynium, the stigmas protruding from a small opening at the tip 3 Carex
+ Ovary or fruit naked, without a saclike covering (2)
2 (1) Plants monoecious, the spikelets with either 1 pistillate floret and somewhat broader scales or with 2–5 staminate florets and narrower scales; fruits appearing hard, white, and bony at maturity, lacking a tubercle 15 Scleria
+ Florets all or mostly perfect, sometimes the apical or basal ones of a spikelet staminate, the scales all alike or not differentiated into 2 kinds; fruits rarely white, not appearing hard and bony at maturity, if rarely white then with a tubercle at the tip (3)
3 (2) Spikelet scales 2-ranked, the spikelets several to many per inflorescence (4)
+ Spikelet scales several-ranked in an overlapping spiral pattern, or if rarely appearing 2-ranked then the spikelets 1 per aerial stem (6)
4 (3) Aerial stems hollow, appearing jointed; inflorescences axillary; florets with bristles 5 Dulichium
+ Aerial stems solid, not appearing jointed; inflorescences terminal; florets without bristles (5)
5 (4) Spikelets with 3 to many alternating scales (2 somewhat reduced scales also at the spikelet base), the fertile florets 2 to many, or if reduced to 1 then the inflorescence noticeably branched, the spikes with short to long stalks 4 Cyperus
+ Spikelets with 2 more or less opposite scales (1–2 highly reduced scales usually visible with magnification at the spikelet base), the fertile floret 1; inflorescence of 1–3 headlike spikes, these short, sessile, dense 10 Kyllinga
6 (3) Style bases enlarged and persistent, forming a conical, triangular, or peglike tubercle on the tip of the fruit that is differentiated in texture and often color from the main body of the fruit (7)
+ Style bases not enlarged, or if thickened then either not persisting on the mature fruit as a tubercle or the fruit tapered to a persistent beak that is not differentiated in texture or color from the main body of the fruit (9)
7 (6) Inflorescences of 1 terminal spikelet; plants essentially leafless, the leaves reduced to 1–4 bladeless sheaths at the base of each aerial stem 6 Eleocharis
+ Inflorescences of 2 to many spikelets; aerial stems with few to many leaves with elongate leaf blades (8)
8 (7) Tubercles minute, peglike 2 Bulbostylis
+ Tubercles prominent, conical or triangular-flattened 12 Rhynchospora
9 (6) Inflorescences of 1 terminal spikelet; plants essentially leafless, the leaves reduced to 1–4 bladeless sheaths at the base of each aerial stem; fruits with a persistent stylar beak 6 Eleocharis
+ Inflorescences of 2 to many spikelets, or if with 1 terminal spikelet, then the stems with several leaves with well-developed leaf blades; fruits not tapered to a persistent stylar beak (10)
10 (9) Involucral bract 1, similar in size and appearance to the bracts of the spikelet, not leaflike or stemlike 16 Trichophorum
+ Involucral bracts 1 to several, at least some of them leaflike or stemlike in appearance (11)
11 (10) Ovaries and fruits subtended by 1–6 (rarely more) scales and/or bristles (do not confuse bristles with the smooth, flattened filaments of the stamens, which can persist after the anthers have dropped off; the bristles generally have a different texture from the filaments and are often barbed) (12)
+ Ovaries and fruits not subtended by bristles or scales (except for the single scale subtending each floret) (16)
12 (11) Ovaries and fruits subtended by scales and bristles or only by scales (these in addition to the 1 larger scale subtending each floret) (13)
+ Ovaries and fruits subtended by bristles only, scales lacking (except for the scale subtending each floret) (14)
13 (12) Bristles absent, the ovaries and fruits subtended by 1–2 small, papery scales 11 Lipocarpha
+ Ovaries and fruits subtended by 3 bristles alternating with 3 scales, these narrowed abruptly to a short stalk 8 Fuirena
14 (12) Involucral bracts 1–3, the main bract erect or nearly so, stemlike, the inflorescence thus appearing lateral (other bracts, if present, inconspicuous) 13 Schoenoplectus
+ Involucral bracts 2 to several, leaflike, the inflorescence appearing terminal (15)
15 (14) Spikelets 10–40 mm long, 6–12 mm in diameter, the scales hairy 1 Bolboschoenus
+ Spikelets 2.5–10.0 mm long, 2–4 mm in diameter, the scales glabrous (rarely glandular) 14 Scirpus
16 (11) Involucral bracts 1–3, the main bract erect or nearly so, stemlike, the inflorescence thus appearing lateral (other bracts, if present, shorter, spreading to reflexed) (17)
+ Bracts subtending the inflorescence (1)2 to several, variously oriented, but leaflike, the inflorescence thus appearing terminal (19)
17 (16) Stigmas 3; fruits 3-angled 9 Isolepis
+ Stigmas 2; fruits biconvex (18)
18 (17) Surface of the fruits minutely pebbled in numerous vertical ranks 11 Lipocarpha
+ Surface of the fruits with fine cross-wrinkles 13 Schoenoplectus
19 (16) Leaves 0.5–2.0 mm wide 7 Fimbristylis
+ Leaves 5–10 mm wide (20)
20 (19) Spikelets 10–40 mm long, 6–12 mm in diameter, the scales hairy; achenes 2.5–5.0 mm long 1 Bolboschoenus
+ Spikelets 2.5–10.0 mm long, 2–4 mm in diameter, the scales glabrous; achenes 0.7–2.0 mm long 14 Scirpus
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