Paul M. Peterson, Stephan L. Hatch and Alan S. Weakley

Plants annual or perennial; usually cespitose, sometimes rhizomatous, rarely stoloniferous. Culms 10-250 cm, usually erect, rarely prostrate, glabrous. Sheaths open, usually glabrous, often ciliate at the apices; ligules of hairs; blades flat, folded, involute, sometimes terete. Inflorescences terminal, open or contracted panicles, sometimes partially included in the uppermost sheath. Spikelets rounded to laterally compressed, with 1(-3) floret(s) per spikelet; disarticulation above the glumes. Glumes 0-1-veined; calluses poorly developed, usually glabrous; lemmas membranous or chartaceous, 1(3)-veined, unawned; paleas glabrous, 2-veined, often splitting between the veins at maturity; anthers (2)3. Fruits utricles or achenes, ellipsoid, obovoid, fusiform, or quadrangular, pericarp free from the seed, becoming mucilaginous when moist in most species, remaining dry and partially adherent to the seed in S. heterolepis and S. clandestinus. Cleistogamous spikelets occasionally present in the lower leaf sheaths. x = 9. Name from the Greek sporos, seed, and bolos, a throw, referring to the free seeds, which are sometimes forcibly ejected when the mucilaginous pericarp dries.

Sporobolus is a cosmopolitan genus of more than 160 species that grow in tropical, subtropical, and warm-temperate regions throughout the world. Seventy-four species are native to the Western Hemisphere; 27 are native to the Flora region, three are established introductions, one was introduced but has not persisted, and the status of one is uncertain. Two genera of the Western Hemisphere, Calamovilfa and Crypsis, resemble Sporobolus in having hairy ligules, spikelets with 1 floret, 1-veined lemmas, and fruits with a free pericarp (Peterson et al. 1997).

Note added December 13, 2005: Previously, Peterson was not sure that Sporobolus pyramidalis P. Beauv. occurred in the Flora region. However, he has now identified a specimen collected in the region as S. pyramidalis, a taxon that he considers distinct from S. jacquemontii Kunth and S. indicus (L.) R. Br.

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SELECTED REFERENCES Baaijens, G.J. and J.F. Veldkamp. 1991. Sporobolus (Gramineae) in Malesia. Blumea 35:393-458; Laegaard, S. and P.M. Peterson. 2001. Flora of Ecuador 68 (ed. G. Harling & L. Andersson). 214(2). Gramineae (part 2): Subfam. Chloridoideae. Botanical Institute, University of Göteborg, Göteborg, Sweden and Section for Botany, Riksmuseum, Stockholm, Sweden. 131 pp.; McGregor, R.L.1990. Seed dormancy and germination in the annual cleistogamous species of Sporobolus(Poaceae). Trans. Kansas Acad. Sci. 93:8-11; Peterson, P.M., R.D. Webster and J. Valdés-Reyna. 1997. Genera of New World Eragrostideae (Poaceae: Chloridoideae). Smithsonian Contr. Bot. 87:1-50; Riggins, R. 1977. A biosystematic study of the Sporobolus asper complex (Gramineae). Iowa State J. Res. 51:287-321; Simon, B.K. and S.W.L. Jacobs. 1999. Revision of the genus Sporobolus (Poaceae, Chloridoideae) in Australia. Austral. J. Bot. 12:375-448; Turner, B.L. 2004. Sporobolus coahuilensis(Poaceae): A new record for the U.S.A. from Trans-Pecos, Texas. Sida 21:455-457; Weakley, A.S. and P.M. Peterson. 1998. Taxonomy of the Sporobolus floridanuscomplex (Poaceae: Sporobolinae). Sida 18:247-270.

T.A. Cope (1993) Poaceae Flora of Somalia 4: 148-270

Plants annual or perennial. Leaves: ligules consisting of a line of hairs. Inflorescences simple panicles, open or contracted, rarely spikelike, exserted from the uppermost leaf sheath. Spikelets with 1-floret, usually without a rachilla extension, fusiform; disarticulation below the glumes; lower glumes usually shorter than the upper; lemmas thinly membranous and often shiny, 1-veined, entire, awnless; anthers 2-3. Grains globose or ellipsoid, rounded or truncate, not beaked; pericarps free, often swelling when wet and expelling the seed from the tip of the spikelets. 

Sporobolus includes about 160 species. They are native from the tropics to the subtropics and warm temperate areas, being particularly common in dry areas. 

Key to the species of Sporobolus in Somaliland and Somalia.

Global distribution of Sporobolus.

Note: GBIF records include introduced and cultivated plants. Consequently, the distribution shown often differs from statements about a taxon's native distribution.