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Cyperaceae

Carex L.

Kingdom: Plantae Rank: Genus Parent: Cyperaceae Status: Valid

Common Names:

  • CARIC SEDGE - English, United States of America

Morphological Description

Diagnosis: Cespitose or rhizomatous grass-like perennial herbs; culms trigonous or infrequently hexagonal or rarely terete, mostly solid, rarely hollow, fertile or both vegetative (including pseudoculms) and fertile culms present; leaves 3-ranked (this helps distinguish the vegetative stage of Carex and other Cyperaceae from grasses); leaf sheaths closed, ligulate; ligule hyaline; leaf blades mostly narrowly linear or sometimes broadly linear (grass-like), rarely otherwise, usually with antrorsely serrulate margins; basal leaves usually more numerous and longer than cauline leaves; inflorescences simple, compound, or decompound, of terminal spikes, terminal and lateral spikes, racemes, spicate-racemes, or open or contracted panicles of spicate or racemose branches; spikes (“spike” is frequently applied to most if not all of these broad ranging inflorescence types in Carex) either unisexual or bisexual, sessile, separate and distinct or crowded into a compact head in which the individual spikes are obscured, or spikes peduncled and distinct, the peduncles either short or long (Braun 1967); bisexual spikes androgynous (= having the staminate flowers distal to the pistillate) or gynecandrous (= having the pistillate flowers distal to the staminate); unisexual spikes arranged so that the staminate spike is terminal, with lateral spikes pistillate or sometimes androgynous; flowers incomplete and imperfect, either pistillate or staminate (all East TX plants monoecious), each solitary in the axil of a single subtending, 1—3-veined pistillate or staminate scale-like bract, without a perianth; staminate flowers with (2–)3 stamens, the filaments in ours filiform and distinct; pistillate flowers enclosed by an indehiscent sac-like scale (the perigynium, the most distinctive feature of the genus) with an apical orifice from which the style and/or stigmas protrude at anthesis; perigynium chartaceous, coriaceous, or membranous in texture, pubescent or glabrous, granular, verrucose, or without any noticeable surface ornamentation, veinless or with several to numerous raised or impressed veins, beaked or beakless, closely enveloping the achene and not at all inflated to strongly inflated, with corky tissue at base or not so, winged or not so; carpels 2 or 3; style withering and deciduous or persistant on the achene, if persistent then the lower portion being of the same color and texture as the achene; stigmas 2—3(–4); ovary 1, with a single ovule; fruit an achene, lenticular, trigonous or subterete (obscurely trigonous), without perianth bristles; chromosome number: n = 6—56 (Tucker 1987).

Other

Notes: A huge cosmopolitan genus of significant taxonomic difficulty, comprising ca. 2,000 species (Ball & Reznicek 2002), mostly in n temperate and arctic regions, of moist to wet habitats but with many dry site species; when tropical mostly montane. In many wetlands, Carex is one of the most prolific and obvious constituents. The polarization of character states is very uncertain and a difficult endeavor in a genus so large and whose phylogeny is so poorly understood (Crins 1990; Reznicek 1990; Naczi et al. 1998). Recent molecular analysis suggests that Carex is paraphyletic, with three smaller genera, Cymophyllus, Kobresia, and Uncinia, derived from within it (Yen & Olmstead 2000); further work is needed to clarify such relationships. It is the largest genus of vascular plants in North America, with 480 species being documented in the recent Flora of North America treatment (Ball & Reznicek 2002). It is also the largest genus in the TX flora, with ca. 95 taxa plus 6 introduced cultivated species that may persist. Further, it is the largest genus in the East TX flora, with 80 species. The genus Carex is divided into taxonomic subdivisions known as sections. Of the 70 sections occurring in North America, 28 can be found in East TX. The appropriate section name is given following each species description. The nursery industry has caught on to the aesthetic beauty of Carex, and almost every nursery has several to many species for sale. The number of cultivated Carex species in TX is surely going to increase. Forage value of Carex for livestock in TX is generally low, but the genus is of use to wildlife, especially rabbits, rodents, deer, and birds, including turkey and bobwhite quail. Martin et al. (1951) listed 77 species of fur or game mammals that feed on Carex. A few of the northern and western United States species (C. geyeri Boott, C. filifolia Nutt., etc.) have high nutritional content and have been used as forage for cattle. Kreczetovicz (1935) stated that up to 5% of hay and pasture production in the USSR was comprised of Carex. In western TX, Carex emoryi Dewey (WILLIAM EMORY’S CARIC SEDGE) is frequently foraged on by cattle while visiting rivers and streams to drink. The genus is also important in preventing soil erosion. Some species are especially important as sand binders in dune areas. Many are pioneer species or species found around ponds and swamps, where they collect alluvium and help in the gradual filling of depressions. In some arctic and alpine regions they are the dominant meadow vegetation. Carex can also be a good ecological indicator, as many species are specific in their habitat requirements (Jermy et al. 1982). Regarding dispersal, “It has been assumed that inflated perigynia are dispersed by floating on water, but experimental verification is lacking” (Tucker 1987). The genus is primarily wind-pollinated, though no species of Carex is known to cause hayfever. Carex albula Allan, C. buchananii Berggr., C. conica Boott ex L.M. Perry, C. flacca Schreb., and C. morrowii Boott var. morrowii and C. muskingumensis Schwein. are cultivars that are widely sold in TX nurseries and may persist depending on local environmental conditions. County records cited in the text are based on the records of S.D. Jones. (The classical Latin name, of obscure origin; possibly from the Greek: keirein, to cut, on account of the sharp leaves—as indicated in the English name SHEAR-GRASS)