Plants annual or of indefinite duration. Culms 10-100 cm long,
erect portion 30-60 cm, long-decumbent, rooting and branching at the decumbent
nodes, sparingly branched or unbranched from the upper nodes; nodes 2-5,
glabrous. Sheaths with papillose-based hairs; ligules 2-3.5 mm,
erose; blades 1.5-14.4(18.9) cm long, 3-9 mm wide, flat, glabrous, a
few scattered papillose-based hairs at the base of the adaxial surfaces (occasionally
overthe whole adaxial surface), usually also scabrous on both surfaces. Panicles
with 2-10 spikelike primary branches, these digitate or in 1-3 whorls on rachises
to 2 cm; lowest panicle nodes with hairs more than 0.4 mm; primary
branches 3-24 cm long, 0.6-1.2(2) mm wide, glabrous or with less than 1
mm hairs, axes wing-margined, wings at least 1/2 as wide as the midribs, lower
and middle portions of the branches with spikelets in unequally pedicellate
pairs; secondary branches absent; shorter pedicels 0.5-1 mm; longer
pedicels 1.5-4 mm. Spikelets (2.7)2.8-4.1 mm long, homomorphic. Lower
glumes 0.2-0.8 mm, acute; upper glumes (1.2)1.5-2.7 mm, about 2/3
to almost as long as the spikelet, 3-veined, margins and apices pilose; lower
lemmas 2.7-4.1 mm, 7-veined, veins unequally spaced, outer 3 veins crowded
together near each margin, well-separated from the midvein, usually smooth,
occasionally the lateral veins scabridulous on the distal 1/3, margins and regions
between the 2 inner lateral veins hairy, hairs 0.5-1 mm (rarely glabrous), sometimes
also with glassy yellow hairs between the 2 inner lateral veins, these more
common on the upper spikelets; upper lemmas 2.5-4 mm, glabrous, yellow,
tan, or gray when immature, becoming brown, often purple-tinged (occasionally
completely purple) at maturity; anthers 0.6-1 mm. 2n = 36 [J.H. Hunziker, F.O. Zuloaga, O. Morrone, and A. Escobar. 1998. Estudios cromosómicos en Paniceae sudamericanas (Poaceae: Panicoideae). Darwiniana 35:29-36], 54.
Digitaria ciliaris is a weedy species, found in open, disturbed areas
in most warm-temperate to tropical regions, primarily in the eastern United
States. It is particularly abundant in the southeast. So far as is known, the
two varieties distinguished in the following key do not differ in any other
characters. They are recognized here pending further study.
Much like no. 4 [Digitaria sanguinalis (L.) Scop.], and intergrading with it; blades glabrous or only sparsely papillose-pilose on the upper surface near the throat; spikelets 2.7-3.6 mm; second glume (1-)1.5-2.5 mm, half to four-fifths the length of the spikelet; lateral veins of the sterile lemma smooth; 2n mostly = 54. A weed as no. 4, but more southern; trop. Amer., n. to Va., s. Ind., Mo., and s. Nebr. (D. adscendens)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.