Plants of indefinite duration; sprawling. Culms to 1 m, erect
portion 20-25 cm, decumbent, rooting and branching freely at the nodes. Sheaths
usually with scattered papillose-based hairs, hairs more abundant on the lower
sheaths; ligules 1.5-1.8 mm, erose; blades 3-14 cm long, 3-9 mm
wide, evenly, often densely pubescent adaxially, hairs papillose-based. Panicles
with 2-14 spikelike branches attached to 4-15 cm rachises, lower branches whorled,
upper branches often paired or solitary; lower nodes with hairs more
than 0.4 mm; primary branches 4-12 cm, axes 0.4-0.7 mm wide, wing-margined,
wings at least 1/2 as wide as the midribs, often with scattered 1-4 mm hairs
proximally, with spikelets in unequally pedicellate pairs on the proximal and
middle portion of the branches; secondary branches rarely present; shorter
pedicels 0.3-0.5 mm; longer pedicels 1.3-2 mm. Spikelets homomorphic,
2.1-2.4 mm, narrowly ovate. Lower glumes 0.1-0.2 mm; upper glumes
1-1.1 mm, 1/3-1/2 as long as the spikelets, 3-veined, margins and apices ciliate;
lower lemmas about as long as the spikelets, lanceolate, 7-veined, lateral
3 veins on each side unequally or equally spaced, smooth or scabrous over the
distal 1/3, lemma margins and the region between the second and third veins
densely pubescent, hairs 0.05-0.1 mm, white; upper lemmas slightly shorter
than the lower lemmas, yellowish or grayish when immature, becoming light brown
at maturity, minutely striate. Caryopses about 1.8 mm, tan. 2n
= 36.
Digitaria horizontalis is native to tropical regions of the Americas.
It has been found in hammocks and disturbed areas in central and southern Florida
and at a few other locations in the southeastern United States, including ballast
dumps in Mobile, Alabama.