Notice: Atrium is currently undergoing maintenance. During this time, some or all images may not be displayed.


Isolepis R.Br.

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

Common Names:

  • BULRUSH - English, United States of America
  • LATERAL BULRUSH - English, United States of America

Morphological Description

Diagnosis: Small tufted annuals (or perennials?) 225(40) cm tall, glabrous or nearly so; culms wiry, very thin, 0.20.5 mm thick near base; leaves near base of culms; ligules absent; leaf blades rudimentary to exceeding sheaths; inflorescences of 13(10) sessile terete spikelets, appearing lateral, with 1(2), spreading to erect, modified leaf (= involucral bract) sometimes appearing like a continuation of the culm; flowers 825 per spikelet; scales of spikelets spirally arranged, keeled, awnless or very short-awned; perianth absent; stigmas usually 3; achenes trigonous to thickly plano-convex, minutely papillose (this can sometimes be obscured by a whitish, wax-like, surface layer), without a tubercle but with a minute beak.


Notes: A cosmopolitan but predominantly s hemisphere genus of 69 species (Muasya & Simpson 2002; Smith 2002c), mostly of temperate and subtropical climates; when tropical, restricted to mountains at higher elevations. Three species are reported for TX (Smith 2002c). Previously included in Scirpus (e.g., Kartesz 1994) and according to some, better treated as a section or subgenus in Scirpus in the broad sense. We are following Smith (1995, 2002c) and Jones et al. (1997) in recognizing this segregate of Scirpus at the generic level. This approach is supported by phylogenetic studies (e.g., Bruhl 1995; Muasya et al. 2000b) which suggest that Scirpus sensu lato is polyphyletic. Recent molecular research (Muasya et al. 2001; Muasya & Simpson 2002) suggests that Isolepis is more closely related to Cyperus than to Scirpus. The key to species is modified from Smith (2002c). (Greek: isos, equal, and lepis, scale)