Digitaria abyssinica

Species

Digitaria abyssinica (Hochst. ex A. Rich.) Stapf

Synonyms

(=Digitaria scalarum (Schweinf.) Chiov.)

Family

Poaceae

Tribe

Paniceae

Common names

African couchgrass, fingergrass

Disseminule

spikelet; disarticulation below the glumes

Description

Spikelets of 1 fertile floret and 1 basal sterile lemma. Spikelets ovate-elliptic, dorsally compressed, plano-convex, 1.5–2.5 mm long, 0.8–1 mm wide, completely glabrous. Pedicel segment often persistent. Glumes 2, dissimilar; lower glume absent or reduced, hyaline; upper glume membranous, slightly shorter than to as long as spikelet. Sterile lemma similar in appearance to upper glume, as long as spikelet. Fertile floret brown at maturity, fertile lemma cartilaginous, shorter than to as long as spikelet, with flat margins enclosing much of palea, faintly muricate.

Identification considerations

Fertile lemmas in the genus Digitaria are flat and thinner at the margins. Distinguishing characteristics of Digitaria abyssinica include its glabrous, unequally pedicelled spikelets and fertile floret that is brown at maturity. See Digitaria velutina (Forssk.) P. Beauv.

Distribution

widespread in tropical Africa, including South Africa and Madagascar; also Sri Lanka, Hawaii

native to eastern Africa

Habitat

moist, shady places, roadsides

General information

Digitaria abyssinica is a perennial rhizomatous grass, up to 80 cm tall. It is reported to be the most troublesome weed in Eastern Africa, invading major crops such as coffee and cotton. Eradication is difficult because propagation is primarily by rhizomes. Cultivation creates rhizome fragments, which can generate new plants. The grass is eaten by livestock, but is not productive enough to be used as a pasture grass.