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Aquatic and Wetland Vascular Plants of the Northern Great Plains

63. Poaceae, the Grass Family

28. Sphenopholis Scribn.

1. Sphenopholis obtusata (Michx.) Scribn. -- Prairie wedgegrass


Tufted or sometimes solitary perennial 2-8 dm tall; culms slender, 0.5-1 mm thick. Leaves ascending to spreading, flat, scabrous, 1-7 mm wide; sheaths glabrous, or the basal ones puberulent; ligule white-hyaline, lacerate, 1-4 mm long. Panicle dense, contracted and spikelike, often interrupted, (1.5)5-12 cm long. Spikelets 2-flowered, 2.5-3.5 mm long, disarticulating below the glumes; glumes 1.5-2.5 mm long, scabrous on the keel, the first glume linear, 1-nerved, the second glume much broader than the first, obovate, 3- to 5-nerved; lemmas acute, 2-3 mm long, scaberulous toward the apex on the keel, 1-nerved; palea exposed, linear, about as long as the lemma, scarious. Grain light brown, elongate, flattened, 1.5-2 mm long. Late Jun--Aug. Low prairie, wet meadows, shores, stream banks and moist woods; common in the e part, becoming uncommon w; (ME to B.C., s to FL, Mex. and CA; also the W.Indies).

Two varieties of S. obtusata occur in the region. Var. obtusata, has the panicle contracted and the second glume 2/3 to fully as wide as long. Var. major (Torr.) Erdman, also known by the name S. intermedia (Rydb.) Rydb., differs in having a more lax, loosely spreading panicle and the second glume 2/5 to 3/5 as wide as long. The former is more often encountered in wet places, whereas var. major is more typical of wooded habitats.

Reference:

Erdman, K. S.  1965.  Taxonomy of the genus Sphenopholis (Gramineae).
     Iowa State Coll. J. Sci. 39:289-336.
GIF- Species Photo/Drawing

Sphenopholis obtusata (from Hitchcock 1950).
GIF- Distribution Map

Map key


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