The Jepson Herbarium
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Annual, perennial herb, often rhizomed or stoloned, often of wet open places; roots fibrous; generally bisexual.
Stem: generally 3-sided, generally solid.
Leaf: generally 3-ranked; base sheathing, sheath generally closed, ligule generally 0; blade (0 or) linear, parallel-veined.
Inflorescence: spikelets generally arranged in head-, spike-, raceme-, or panicle-like inflorescences; flower generally sessile in axil of flower bract, enclosed in a sac-like structure ( perigynium) or generally not.
Flower: small, generally wind-pollinated; perianth 0 or generally bristle like; stamens generally 3, anthers attached at base, 4 chambered; ovary superior, chamber 1, ovule 1, style 2–3-branched.
Fruit: achene, 2–3 sided.
± 100 genera, 5000 species: especially temperate. [Ball et al. 2002 FNANM 23:1–608] Difficult; taxa differ in technical characters of inflorescence, fruit. In Carex and Kobresia, what appear to be pistillate flowers in fact are highly reduced inflorescences (whether or not the same applies to staminate flowers is still under debate). In some other works (e.g., FNANM) these are called spikelets, and they are treated as being arranged in spikes. Here and in TJM (1993), what appear to be pistillate flowers are called pistillate flowers in Carex (and they are treated as being arranged in spikelets), but spikelets in Kobresia (and they are treated as being arranged into spikes). Though internally inconsistent, the approach here is consistent with traditional usage, and reflects a preference for character states that may be determined in the field. —Scientific Editors: S. Galen Smith, Thomas J. Rosatti, Bruce G. Baldwin.
Unabridged references: [Tucker 1987 J Arnold Arbor 68:361–445; Bruhl 1995 Australian Syst Bot 8:125–305]

Key to Cyperaceae

1. Fl, fruit enclosed in sac-like structure (perigynium); flowers unisexual

2. Perigynium open at tip ..... CAREX

2' Perigynium open on 1 side ..... KOBRESIA

1' Fl, fruit not enclosed in sac-like structure; flowers bisexual or some staminate

3. Fl bracts 2-ranked; spikelets generally flat

4. Infl in leaf axils; leaves cauline; stem internodes hollow ..... DULICHIUM

4' Infl terminal; leaves basal or basal and cauline; stem internodes solid or spongy with air cavities

5. Spikelets with >= 2 sterile proximal flower bracts; leaf sheaths ± black; inflorescence head-like ..... SCHOENUS

5' Spikelets with 0–1 sterile proximal flower bracts; leaf sheaths not ± black; inflorescence head-like or not

6. Spikelets with 2–36 flower bracts ..... CYPERUS

6' Spikelets with 2(3) flower bracts ..... KYLLINGA

3' Fl bracts spiraled (except Isolepis levynsiana); spikelets not flat (± flat in Isolepis levynsiana)

7. Fl stems generally with cauline leaves 0 (1–2 cauline in Schoenoplectus saximontanus)

8. Infl bracts 0; spikelet 1; leaves 2, blade 0 or tooth-like, <= 1 mm; fruit tubercle generally present ..... ELEOCHARIS

8' Infl bracts >= 1; spikelets >= 1; leaves 1–3, generally some clearly bladed; fruit tubercle 0

9. Fl bract (outer if 2) with >= 3 veins; stem <= 40 cm

10. Fl bract 1 per flower ..... ISOLEPIS

10' Fl bracts (1)2 per flower (a 2nd, inner bract between flower, spikelet axis generally present) ..... LIPOCARPHA

9' Fl bract with 1 vein, at least in distal-most part of spikelet; stem <= 400 cm

11. Sts <= 15 cm, < 1 mm diam; spikelets 1, 3–4.6 mm, 1.5–2.8 mm wide ..... TRICHOPHORUM

11' Sts (1)10–400 cm, <= 10 mm diam; spikelets 1–200, 3–23 mm, 2–7 mm wide

12. Ligule ciliate; stem, leaf air cavities 0; stem wiry; flower bracts shiny, in proximal part of spikelet 3–9-veined, at least in distal-most 1-veined, tip not notched ..... AMPHISCIRPUS

12' Ligule glabrous; stem, leaf generally with air cavities; stem rarely wiry; flower bracts dull, 1-veined, tip generally notched ..... SCHOENOPLECTUS

7' Fl stems with cauline leaves >= 1 (see also Schoenoplectus saximontanus)

13. Infls generally > 1, generally >= 1 in leaf axil

14. Fls 10–50 per spikelet ..... SCIRPUS

14' Fls < 6 per spikelet

15. St 5–10 mm diam; leaf blades 5–10 mm wide, margins saw-toothed ..... CLADIUM

15' St <= 2 mm diam; leaf blades 0.5–5 mm wide, margins generally scabrous ..... RHYNCHOSPORA

13' Infl 1, terminal

16. Lf sheath tip margins scabrous or ciliate; stem, leaf blades glabrous or generally ± scabrous or puberulent

17. Lf sheath tip ciliate, hairs >> 1 mm, soft ..... BULBOSTYLIS

17' Lf sheath tip scabrous, hairs << 1 mm, stiff ..... FIMBRISTYLIS

16' Lf sheath tip margins glabrous; stem, leaf blades glabrous or on keels or angles scabrous

18. Fl bracts puberulent (glabrous in age), tip notched, generally with curved awn often broken off; stem sharply 3-angled; tubers durable ..... BOLBOSCHOENUS

18' Fl bracts glabrous, tip entire, awn 0; stem 3-angled or cylindric; tubers 0 ..... ERIOPHORUM

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Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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