Jepson Flora Project: Jepson Interchange    

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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California
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Raymond Cranfill, except as specified

Annual or perennial herb, often rhizomed, often of wet open places, generally monoecious; roots fibrous, hairy
Stem generally 3-sided
Leaves often 3-ranked; sheath generally closed; ligule generally 0; blade (0) various, parallel-veined
Inflorescence: spikelets variously clustered; flowers generally sessile in axil of flower bract
Flower small, generally wind-pollinated; perianth 0 or bristle-like; stamens generally 3, anthers attached at base, 4-chambered; ovary superior, 1-chambered, 1-ovuled, style 2–3-branched
Fruit: achene, generally 3-sided
Genera in family: ± 110 genera, 3600 species: worldwide, especially temp
Reference: [Tucker 1987 J Arnold Arbor 68:361–445]
Difficult: taxa differ in technical characters of inflorescence and fruit.



Gordon C. Tucker

Annual or perennial herb, glabrous
Stems generally > 1, erect, 2–100 cm, 3-angled or round
Leaves basal; blades 0 or linear
Inflorescence: bracts 1–9, leaf-like, spreading or erect; rays < 10 cm; spikelets flat to ± cylindric; flower bracts 2-ranked, 1 per flower, 2–36 per spikelet
Flower bisexual; perianth 0; stigmas generally 3
Fruit (ob)ovoid, generally 3-angled, brown, generally not beaked
Etymology: (Greek: name for 1 sp.)
Reference: [Tucker 1983 Syst Bot Monogr 2:1–85]
Mature fruit generally needed for identification. C. unioloides R. Br. and C. virens Michx. probably only waifs in CA.


C. difformis L.

Annual 3–40 cm
Inflorescence: bracts 2–3; rays 0–4, 6–30 mm; spikelets 50–100+ in dense, subspheric, yellowish or purplish, rayed or sessile heads; flower bracts 6–30 per spikelet, 0.6–0.8 mm, obovate, yellow to yellowish brown
Fruit 0.6–0.8 mm, obovoid-ellipsoid, glossy
Ecology: Ditches, pond shores, rice fields
Elevation: 100–500 m.
Bioregional distribution: Great Central Valley, Southwestern California
Distribution outside California: native to Old World

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bioregional map for CYPERUS%20difformis being generated
YOU CAN HELP US make sure that our distributional information is correct and current. If you know that a plant occurs in a wild, reproducing state in a Jepson bioregion NOT highlighted on the map, please contact us with that information. Please realize that we cannot incorporate range extensions without access to a voucher specimen, which should (ultimately) be deposited in an herbarium. You can send the pressed, dried collection (with complete locality information indicated) to us (e-mail us for details) or refer us to an accessioned herbarium specimen. Non-occurrence of a plant in an indicated area is difficult to document, but we will especially value your input on those types of possible errors (see automatic conversion of distribution data to maps).

Retrieve Jepson Interchange Index to Plant Names entry for Cyperus difformis
Retrieve dichotomous key for Cyperus
Overlay Consortium of California Herbaria specimen data by county on this map
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