sand dropseed
Sporobolus cryptandrus (Torrey) A. Gray

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Sand dropseed is widespread in the western two-thirds of North America, extending from Canada to Mexico. In Iowa, sand dropseed is most common along the eastern and western borders, although it is scattered across the state, growing in sandy prairies and loess bluffs as well as along lake shores. This species is readily distinguished from other dropseeds in Iowa by the conspicuous tufts of hair at the sheath summits, its narrowly pyramid-shaped flowering heads, and its relatively small spikelets. Sand dropseed flowers in August and September in Iowa.

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; cryptandrus from the Greek crypto- meaning hidden and the Greek -andrus meaning male, referring to the flowering heads that are partially concealed within the leaf sheaths.


Plants perennial, tufted, usually not rhizomatous. Culms 25-105 cm tall. Leaves with the sheaths open, usually smooth, with a conspicuous tuft of hairs at the summit; ligules 0.1-0.5 mm long, a line of hairs; blades (3-) 9-21 cm long, 2-7 mm wide, flat to rolled, both surfaces smooth. Flowering heads terminal, 6-23 cm long, 2-11 cm wide, contracted at first, becoming narrowly pyramidal as the branches spread out, partially or sometimes completely enclosed by the subtending leaf sheath; primary branches spreading from the main axis at maturity. Spikelets 1.7-3 mm long, straw- to lead-colored, smooth, laterally compressed, lacking any awns; glumes unequal, membranous, usually 1-nerved, lower glumes 0.8-1.3 mm long, upper glumes 1.6-2.2 mm long, about 3/4 the length of the florets; lemmas 1.6-2.4 mm long, 1-nerved, membranous, acute; paleas 1.5-2.6 mm long, more or less equaling the lemma, 2-nerved, membranous. Fruits 0.7-1.1 mm long, ellipsoid, reddish-brown. Chromosome number 2n = 72.


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