Vegetative Morphology
Culms	(9)20-130 cm.
Ligules	(1)1.5-2.5 mm, erose-ciliate and more or less lacerate.
Blades	5-14 cm long, (1)2-8 mm wide, flat, rarely slightly involute.
Reproductive Morphology
Panicles	(2)5-15(25) cm long, 0.5-2 cm wide, usually erect, usually spikelike, spikelets usually densely arranged.
Spikelets	2.2-3.6 mm.
Lower glumes	less than 1/3 as wide as the upper glumes.
Upper glumes	1.5-2.5 mm, subcucullate, width/length ratio 0.3-0.5.
Lowest lemmas	1.9-2.8 mm, usually scabridulous distally.
Distal lemmas	usually smooth, occasionally scabrous, unawned.
Anthers	0.2-1 mm.

Chromosome Number(s)

2n = 14

Typical Habitat(s)

Found in prairies, marshes, dunes, forests, and waste places from 0-2500 meters.

Nativity / Range

Found from British Columbia to Prince Edward Island south, throughout the United States.

Similar Species

Occasional plants of S. obtusata with scabrous distal lemmas can be distinguished from:

S. nitida by their narrower lower glumes;

S. filiformis by their wider leaves;

S. pensylvanica by their shorter, unawned spikelets.

Hybrids with S. pensylvanica, called Sphenopholis xpallens (Biehler) Scribn., have short (0.1-4 mm) awns on the distal lemmas.

Name/Synonymy Publication Info

Sphenopholis obtusata (Michx.) Scribner, Rhodora 8:144 (1906). Aira obtusata Michx., Fl. bor.-amer. 1:62 (1803); Airopsis obtusata (Michx.) Desv., J. Bot.(Desvaux) 1:200 (1808); Poa obtusata (Michx.) Link, Hortus berol. 1:76 (1827); Reboulea obtusata (Michx.) A. Gray, Manual 591 (1848); Eatonia obtusata (Michx.) A. Gray, Manual, ed. 2, 558 (1856). Aira truncata Muhl., Cat. pl. Amer. sept. 11 (1813), nom. superfl. LEC: P (P-MICH) [slender specimen], fragment & photo US 72667, photo NY; U.S.A., Florida; A. Michaux [Hitchc., Contr. U.S. Natl. Herb. 123:152 (1908)].

Aira truncata Muhl., Descr. gram. 83 (1817), non Muhl. (1813); Koeleria truncata (Muhl.) Torrey, Fl. n. middle United States 1:116 (1823); Reboulea truncata (Muhl.) Torrey in Munro, J. Proc. Linn. Soc., Bot. 6:43 (1862). TYPE: U.S.A., Pennsylvania.

Koeleria paniculata Nutt., Gen. N. Amer. pl. 2:add. 2 (1818). TYPE: U.S.A., Florida: east Florida; T. Say.

Trisetum lobatum Trin., M?m. Acad. Imp. Sci. St.-P?tersbourg, Ser. 6, Sci. Math. 1:66 (1830); Koeleria lobata Trin. ex Steudel, Nomencl. Bot., ed. 2, 1:849 (1840), non (M.-Bieb.) Roemer & Schultes (1817); Sphenopholis obtusata subsp. lobata (Trin.) Scribner, Rhodora 8:144 (1906); Sphenopholis obtusata var. lobata (Trin.) Scribner ex B.L. Rob., Rhodora 10:65 (1908); Reboulea obtusata var. lobata (Trin.) Farw., Rep. (Annual) Michigan Acad. Sci. 17:182 (1916). TYPE: North America.

Reboulea gracilis Kunth, R?vis. gramin. 1:341, pl. 84 (1830). TYPE: U.S.A., New England, Florida, and "Carolina".

Graphephorum densiflorum E. Fourn., Bull. Soc. Bot. France 24:182 (1877), nom. nud.; Eatonia densiflora E. Fourn., Mexic. pl. 2:111 (1886). TYPE: B, fragment US; "M?xico" [U.S.A., Texas]: Bejar; J.L. Berlandier 1617.

Eatonia obtusata var. robusta Vasey ex L.H. Dewey in J.M. Coulter, Contr. U.S. Natl. Herb. 23:544 (1894). TYPE: U.S.A., western Texas [Wallisville] to Arizona; 1881; Wallis.

Eatonia obtusata var. robusta Vasey ex Rydb., Contr. U.S. Natl. Herb. 33:190 (1895); Eatonia robusta (Vasey ex Rydb.) Rydb., Bull. Torrey Bot. Club 32:602 (1905); Sphenopholis robusta (Vasey ex Rydb.) A. Heller, Muhlenbergia 6:12 (1910). TYPE: U.S.A., Nebraska: Mullen; P.A. Rydberg 1807.

Eatonia obtusata var. purpurascens Vasey ex Rydb. & Shear, Bull. Div. Agrostol. U.S.D.A. 5:30 (1897); Sphenopholis obtusata var. lobata forma purpurascens (Vasey ex Rydb. & Shear) Waterf., Rhodora 50:93 (1948). TYPE: U.S.A, Oklahoma: False Washita; 1868; E. Palmer 404.

Eatonia pubescens Scribner & Merr., Circ. Div. Agrostol. U.S.D.A. 271:6 (1900); Sphenopholis obtusata subsp. pubescens (Scribner & Merr.) Scribner, Rhodora 8:144 (1906); Sphenopholis obtusata var. pubescens (Scribner & Merr.) Scribner ex Rob., Rhodora 10:65 (1908); Sphenopholis pubescens (Scribner & Merr.) A. Heller, Muhlenbergia 6:12 (1910); Reboulea obtusata var. pubescens (Scribner & Merr.) Farw., Rep. (Annual) Michigan Acad. Sci. 17:181 (1916). HOL: US 72670; U.S.A., Mississippi: Starkville; 30 Apr 1891; S.M. Tracy.

Eatonia annua Suksd., W. Amer. Sci. 15:50 (1906); Sphenopholis annua (Suksd.) A. Heller, Muhlenbergia 6:12 (1910). TYPE: U.S.A., Oregon: The Dalles on Columbia River; 8 Jun 1897; W.N. Suksdorf 1553.

Treatment From

T.F. Daniel. Sphenopholis in Flora of North America, volume 24. In prep. Oxford University Press.

Vegetative Morphology