General: Annual grass from fibrous roots, basally branching; stems decumbent to erect, 10-100 cm tall.
Leaves: Sheaths keeled, smooth; blades flat to folded, 4-11 mm wide, smooth or fringed with soft fine hairs at the throats, the collars slightly hairy or smooth; ligules scarcely 2 mm long, fringed with fine hairs.
Flowers: Inflorescence a rather narrow, cylindrical panicle, not obviously lobed, rarely over 10 cm long, 15 mm wide when pressed; spikelets 2-flowered, 3-3.6 mm long, each subtended by 2 or 3 (4), rough bristles that are up to 3 times as long as the spikelets, the hairs directed upwards; lower flowers staminate or sterile, the upper fertile; fertile lemmas and paleas nearly completely enclosed by the upper glumes and sterile lemmas, and not shed separately from them, usually evidently cross-wrinkled when mature.
If more than one illustration is
available for a species (e.g., separate illustrations were provided for two
subspecies) then links to the separate images will be provided below.
Note that individual subspecies or varietal illustrations are not always available.
The table below shows the species-specific information calculated from original data (BEC database) provided by the BC Ministry of Forests and Range. (Updated August, 2013)
Setaria viridis is difficult to distinguish from Setaria faberi (Pohl 1962). Dore and McNeill (1980) and Pohl (1962) indicate that S. viridis is primarily glabrous while S. faberi usually has hairs on the upper surface of the leaf blades. Pohl says "The prevalent form of S. faberia bears soft pubescence on the upper leaf surfaces only and is usually distinguished from other species on this basis." However, leaf pubescence is not always a reliable character, in general; features of the spikelets may be more reliable separators (Pohl 1962).
