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Bolboschoenus (Asch.) Palla

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

Common Names:

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

Morphological Description

Diagnosis: Rhizomatous perennials to ca. 1.5 m tall, often forming dense stands; rhizomes 1–5 mm thick; corms (“tubers”) developing at base of culms, to ca. 20 mm thick; culms sharply triangular, with nodes, usually 3–8 mm in diam.; leaves basal and cauline, several; leaf sheaths reaching ca. to middle of culm or beyond; ligules absent; leaf blades well-developed, to 12 mm wide; inflorescence terminal, with 2 or more well-developed, leaf-like, involucral bracts (1–4 of them longer than the inflorescence); spikelets large, 10–30(–40) mm long, usually few in number, (1–)2–15 (–40), either all sessile or some single or clustered on peduncles, round in cross section; scales of spikelets 25 or more per spikelet, spirally arranged, apically notched, awned; perianth bristles 3–6, not persistent on fallen achenes or a few persistent; stamens 3; styles bifid or trifid; achenes biconvex to compressed trigonous, without a tubercle.


Notes: A genus of 6–15 species (Smith 2002a) known from North America, Eurasia, Central and South America, Africa, Australia, and some Pacific Islands. Four species are native to North America n of Mexico, and 1 naturalized. Previously included in Scirpus (e.g., Kartesz 1994) and sometimes treated as a section or subgenus in Scirpus in the broad sense. Strong (1993, 1994) and Kartesz (1999) included Bolboschoenus in Schoenoplectus. Smith (2002a), however, pointed out several differences between the genera (e.g., Bolboschoenus with leaves basal and cauline, without ligules vs. Schoenoplectus with leaves usually all basal, with ligules). We are thus following Browning et al. (1995b), Smith (1995, 2002a), 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. Some species are dominants in wetlands and can be valuable to wildlife (Kantrud 1996; Smith 2002a). The following key to species is modified from that in Smith (2002a). (Greek: bulbus, bulb, and schoeno, reed or rush-like, in reference to the corms)