Digitaria velutina (Forssk.) P. Beauv.

Family: Poaceae,  Tribe: Paniceae

Common names:  velvet fingergrass, annual couchgrass

Disseminule:  Spikelet, disarticulation below the glumes.

Description

Spikelets of 1 fertile floret and 1 basal sterile lemma. Spikelets elliptic, dorsally compressed, plano-convex, 1.5-2.1 mm long, 0.5-0.6 mm wide. Pubescent, with short to long hairs between nerves on upper glume and sterile lemma. Glumes dissimilar; lower glume a small scale or absent; upper glume membranous, 1.2-1.6 mm long. Sterile lemma membranous, as long as spikelet. Fertile lemma cartilaginous, striate, as long as spikelet, with flat margins covering much of palea.

Identification remarks

Fertile lemmas in the genus Digitaria are flat and thinner at the margins. See Digitaria abyssinica (Hochst. ex A. Rich.) Stapf

Similar species

Digitaria horizontalis Willd.

Distribution

Widespread in tropical Africa, including South Africa; Asia: China, India, Japan, Korea, Malaysia, Taiwan; Oceania: Micronesia; North America: Costa Rica, United States.

Native to Eastern Africa.

Habitat

Sandy soils, damp places; fields, plantations, open brush.

General information

Digitaria velutina is a slender, annual grass, up to 100 cm tall. It is a quickly invading, common weed of arable land in Africa. Propagation is by the grains, which are highly viable. This grass has been used as a forage plant.

Spikelets, florets, caryopses, and portion of inflorescence

photo by Mark Thurmond

Spikelets, florets, and caryopses

photo by Mark Thurmond

Spikelets in dorsal view showing upper glume and fertile lemma

Spikelets in ventral view showing sterile lemma

A, Spikelet in ventral view showing sterile lemma; B, spikelet in dorsal view showing upper glume and fertile lemma; C, floret in ventral view showing palea and margins of lemma; D, floret in dorsal view showing lemma; E, caryopsis in ventral view; F, caryopsis in dorsal view

drawing by Lynda E. Chandler

Portion of inflorescence showing spikelets