Compilation
Setaria palustris

A tall grass up to 8 ft. high; base unknown. Culms erect, moderately stout, simple or sparingly branched, the uppermost internode (peduncle) up to 1 ft. long, finely striate, glabrous and smooth except close to the spike where it is very finely downy. Leaf-sheaths finely striate, glabrous and smooth; ligule a very densely ciliate rim; blade linear from a very slightly constricted and more or less narrowed base, long-tapering upwards, flat, flexuous, up to 1 1/2 ft. long by 5–6 lin. wide, green or slightly glaucous, glabrous except for the usually tomentellous motile zone, more or less rough along the margins and sometimes also on the main nerves, midrib rather obtusely prominent downwards on the back, correspondingly channelled on its face, primary lateral nerves slender, 1/2 lin. distant at the middle of the blade. Inflorescence a moderately dense false spike, 5–12 in. long by 3–3 1/2 lin. wide (at the middle, exclusive of the bristles); axis more or less angular or almost terete upwards, densely puberulous; branches slender, very short or somewhat elongated, rarely the lowest up to 4 lin. long, forming dense or loose clusters of 2–4 perfect and a few very much reduced spikelets; bristles slender, very unequal, the longest up to over 6 lin. long, up to 20 in a cluster, scaberulous, pale throughout or purplish at the tips. Spikelets rather turgid, elliptic-oblong, 1 1/2 lin. long by 4/5 lin. wide in back view, very broadly semi-ovate and up to over 1 lin. wide in profile, whitish, very smooth. Glumes membranous; lower broadly ovate, apiculate, 5-nerved, half or nearly half the length of the spikelet; upper elliptic, very blunt, minutely apiculate, 7-nerved, three-quarters the length of the upper floret. Lower floret ♂: valve similar to the upper glume, but narrower and as long as the spikelet, 5-nerved; valvule elliptic or elliptic-ovate, almost as long as the valve; anthers 1 lin. long. Upper floret hermaphrodite, slightly shorter than the lower: valve ovate-oblong, subacuminate, scaberulous at the tip, hardly 1/2 lin. wide in back view, semi-ovate, very much curved and 1/2 lin. wide in profile, finely punctate, without transverse wrinkles, whitish, or the exposed tips with a dark purple blotch; valvule very narrow as seen between the parallel widely involute margins of the valve.