Setaria pumila (Poir.) Roem. & Schult. ssp. pallidefusca (Schumach.) B.K. Simon
(=Setaria pallidefusca (Schumach.) Stapf & C.E. Hubb.)
Family Poaceae, Tribe Paniceae
Spikelets of 1 fertile floret and 1 basal sterile lemma; spikelets elliptic, dorsally compressed, plano-convex; 2.0–2.8 mm long, 1.1–1.7 mm wide, 0.9–1.3 mm thick, average length/width ratio 1.8. Glumes membranous; lower glume one third as long as spikelet, 3-nerved, acute; upper glume half as long as spikelet, 5-nerved. Sterile lemma similar to glumes, but as long as spikelet, 5-nerved. Fertile lemma indurate, whitish-yellow to brown, usually with a satiny sheen, with widely spaced transverse ridges cut longitudinally, resulting in a characteristic hatching effect, lemma margins inrolled, enclosing palea; palea glossy margins not visible. Caryopsis 1.4–2 mm long.
Characters that may help to differentiate among Setaria spikelets are: fertile lemma ridges widely vs. closely spaced; glossy margins of palea exposed vs. not exposed; edge view profile; glume lengths.
Setaria pumila (Poir.) Roem. & Schult. ssp. pumila (spikelets 2.9–3.4 mm long, 1.9–2.3 mm wide, 1.2–1.6 mm thick, outline broadly elliptic, average length/width ratio 1.5, lower glume half to two-thirds length of spikelet, upper glume half length of spikelet) (non-FNW)
widespread in tropical Africa including South Africa; Asia: Indian subcontinent and China, Indonesia, Japan, Korea, Philippines, Taiwan, Thailand; Oceania: Australia, Fiji, Polynesia; Europe: Germany; United States
a weed of croplands, grasslands, roadsides, ditches, waste places, shady places
Setaria pumila ssp. pallidefusca is an annual grass, to 100 cm tall, distinct from the common weed S. pumila (Poir.) Roem. & Schult. ssp. pumila (yellow foxtail). Originally listed as Setaria pallidefusca, this weed is now considered a subspecies of S. pumila. Well adapted to a wide range of soil and climate conditions, S. pumila ssp. pallidefusca reduces yields of a diversity of crops in 36 countries. It is eaten by cattle as a fodder grass.
spikelets in ventral view showing lower glume and sterile lemma (top) and dorsal view showing upper glume and fertile lemma (bottom)