prairie dropseed
Sporobolus heterolepis (A. Gray) A. Gray

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habithabitinflorescenceinflorescencespikelet, floretillustration

Prairie dropseed, as the name suggests, is characteristic of tall grass prairies in most of Iowa, especially the drier parts of prairies, but it is apparently absent from the loess soil areas of the western counties of Iowa. In North America, this species is distributed from Quebec and Connecticut in the northeast to Saskatchewan, Colorado, Wyoming and eastern Texas in the west, and can occur in other habitats such as woodland borders. In Iowa, this grass flowers from August to October, but not all plants will flower every year in a given location. The fine-textured, drooping leaves are very attractive, giving this grass ornamental potential. Prairie dropseed is virtually unique among grasses in producing a pleasant, aromatic scent from the flowering heads. The scent is produced from small, elongated glands at the base of the branches. Runkel and Roosa (1989) note that the fruits are fragrant, and also indicate that the grains were ground for flour by the Kiowa.

Etymology: Sporobolus from the Greek sporo = seed and ballein = to throw, referring to the free seeds in many species of this genus that are sometimes forcibly ejected when the usually mucilaginous fruit wall dries; heterolepis from the Greek heteros = different and lepis = scale, referring to the unequal, scale like glumes of this species.


Plants perennial, tufted, clumps circular and sometimes large, not rhizomatous. Culms 35-120 cm tall. Leaves with the sheaths open, glabrous to scattered pilose near the summit; ligules a line of hairs 0.1-0.3 mm long; blades (7) 12-35 (-45) cm long, 1.2-2.5 mm wide, flat to folded, drooping, the lower surface glabrous, the upper surface scaberulous. Flowering heads terminal, well exserted, 8-20 cm long, 1.5-6 cm wide, open to somewhat contracted, narrowly pyramidal; primary branches appressed or spreading from the main axis, slightly swollen at the base, spikelets lacking from the lower one-third, a small, slightly elongated gland present on the lower third of the branch at least on the lower branches. Spikelets 3.5-6 mm long, reddish to lead-colored but sometimes straw-colored, especially when dry, glabrous, weakly laterally compressed to weakly dorsally compressed; glumes unequal, lanceolate, membranous, usually 0-1-nerved, lower glumes 2.3-4.5 mm long, upper glumes 4-5.5 mm long, at least 2/3 the length of the florets; lemmas 3.5-4.3 mm long,1-nerved, membranous, acute; paleas 3.6-4.5 mm long, slightly longer than the lemma, 2-nerved, often splitting between the nerves at maturity, membranous. Fruits 1.4-2.1 mm long, pear-shaped to spherical, hardened, smooth, shiny, light brown to golden. Chromosome number 2n = 72.



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