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FNA | Family List | FNA Vol. 23 | Cyperaceae

11. BULBOSTYLIS Kunth, Enum. Pl. 2: 205. 1837.

Bulbostyle [Latin bulbus, bulb, and stylus, style]

Robert Kral

Oncostylis Martius; Stenophyllus Rafinesque

Herbs, annual or perennial, cespitose, scapose, not rhizomatous. Roots diffuse, very fine. Culms stiff or flaccid, usually terete, ribbed. Leaves basal, polystichous, spreading to ascending; sheaths open apically, apex fimbriate-ciliate, rarely entire; ligules absent, lateral tufts of hair at junction of blade and sheath; blades mostly linear or filiform, coarsely ribbed, usually longer than sheaths, 1 mm wide or less, mostly strongly involute, margins variably scabrid-ciliate. Inflorescences terminal on slender scapes, rarely axillary to culm leaves, simple or compound anthelae or spikelet solitary; spikelets 1–50+; involucral bracts (1–)2–8, spreading or erect, leaflike or scalelike. Spikelets mostly ovoid to lanceoloid or lance-cylindric; scales 6–50, spirally arranged, rarely nearly distichous, each subtending flower or 1–2 proximal scales empty. Flowers bisexual; perianth absent; stamens 1–3; styles slender, (2–)3-fid, glabrous, base enlarged, persistent in fruit. Achenes trigonous or 3-lobed, rarely biconvex, usually 3-ribbed.

Species ca. 100 (8 in the flora): mostly of dry or periodically dry, sunny, sandy uplands, particularly savanna in warm-temperate and tropical regions worldwide.

Culms of bulbostylises are coarse or fine, leafy only at the base, and terminating in scape (or rarely not scapose). Scapes are linear to filiform, wiry, variously ribbed. Spikelets or florets are short-stalked, even sessile in leaf axils. Flowers are protandrous and subsessile on short pedicellar joints; anthers are mostly linear-oblong or oblong-elliptic, two- to four-sporangiate, bilocular; style base is articulated to ovary summit and persists on fruit as buttonlike tubercle.


Kral, R. 1971. A treatment of Abildgaardia, Bulbostylis and Fimbristylis (Cyperaceae) for North America. Sida 4: 57–227. Lye, K. A. 1971b. The generic concept of Bulbostylis Kunth ex C. B. Clarke. Mitt. Bot. Staatssamml. München 10: 539–547.

1 Spikelets sessile or subsessile, forming globose to hemispheric head, head subtended by setaceous-tipped or cuspidate involucral bracts.   (2)
+ Spikelets either solitary at culm tip or in anthelae, sometimes short-stalked (B. capillares), at plant base in leaf axils.   (4)
2 (1) Achene faces finely reticulate, not transversely rugose or rugulose; achenes 0.5–0.6 mm; spikelets red, red-brown, or dull brown; longer involucral bracts rarely exceeding inflorescence.   3 Bulbostylis barbata
+ Achene faces transversely rugose or rugulose; achenes 1–1.2 mm; spikelets pale or greenish or tan; longer involucral bracts exceeding inflorescence.   (3)
3 (2) Involucral bracts with broad, scarious, strongly pectinate-fimbriate sheath border abruptly narrowing to blade; plants perennial, to 50 cm; anthers 3, 3 mm.   1 Bulbostylis warei
+ Involucral bracts with scarious, entire border gradually narrowing to blade; plants annual, to 20 cm; anthers 1, 0.5 mm.   2 Bulbostylis stenophylla
4 (1) Spikelets 1 per culm; plants diminutive, delicate annuals.   (5)
+ Spikelets prevalently more than 1 per culm, in anthelae; plants tall annuals or peren-nials.   (6)
5 (4) Spikelets of 2 sorts, sterile and fertile, respectively producing non-viable achenes, 1 mm or less, or viable achenes, 1.5 mm, in sheath axils at culm base.   4 Bulbostylis funckii
+ Spikelets fertile, achenes all viable, 1 mm.   5 Bulbostylis schaffneri
6 (4) Surface of ripe achenes waxy gray, evenly papillate; Coastal Plain of United States.   6 Bulbostylis ciliatifolia
+ Surface of ripe achenes pale red-brown, greenish or yellow-brown, tan, or gray, minute alveolae or papillae raised into finely or coarsely transversely rugose or rugulose faces; wider distribution.   (7)
7 (6) Plants hard-based, perennial; achene surfaces gray, yellow-brown or dark brown, rugulose, papillate; stamens 3; anthers 1 mm.   7 Bulbostylis juncoides
+ Plants soft-based, annual; achene surfaces mostly yellow to pale brown, rugose, not papillate; stamens (1–)2; anthers 0.5–0.7 mm.   8 Bulbostylis capillaris

Lower Taxa


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