Northern Prairie Wildlife Research Center
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.
Erdman, K. S. 1965. Taxonomy of the genus Sphenopholis (Gramineae).
Iowa State Coll. J. Sci. 39:289-336.
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