Setaria pumila ssp. pallidefusca

Name and classification

Setaria pumila (Poir.) Roem. & Schult. ssp. pallidefusca (Schumach.) B.K. Simon
(=Setaria pallidefusca (Schumach.) Stapf & C.E. Hubb.)
Family Poaceae, Tribe Paniceae

Common names

cattail grass

Disseminule

spikelet, disarticulation below glumes

Description

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.

Identification considerations

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.

Similar species

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)

Setaria parviflora (Poir.) Kerguelen (spikelets 2.0–2.8 mm long, 1.25 mm wide, in edge view thickest in lower half, tapering above the middle to a long-pointed apex) (non-FNW)

Distribution

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

Habitat

a weed of croplands, grasslands, roadsides, ditches, waste places, shady places

General information

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)

spikelets in ventral view showing lower glume and sterile lemma (top) and dorsal view showing upper glume and fertile lemma (bottom)

spikelets in dorsal view

spikelets in dorsal view

florets in ventral view showing palea and margins of lemma

florets in ventral view showing palea and margins of lemma

caryopses in dorsal view (left) and ventral view (right)

caryopses in dorsal view (left) and ventral view (right)

A, spikelet in ventral view; B, spikelet in dorsal view; C, floret in ventral view; D, floret in dorsal view; E. caryopsis in ventral view; F, caryopsis in dorsal view; drawing by Lynda E. Chandler

A, spikelet in ventral view; B, spikelet in dorsal view; C, floret in ventral view; D, floret in dorsal view; E. caryopsis in ventral view; F, caryopsis in dorsal view; drawing by Lynda E. Chandler