Setaria verticillata (L.) P.Beauv.
rough bristle grass
Narrowly tufted annuals, bright green, usually with few branches at base, usually 20-40-(100) cm. Leaf-sheath light green or purplish, submembranous, rounded, to slightly keeled above, smooth apart from minutely scabrid ribs below collar; margins ciliate, hairs tubercle-based. Ligule ciliate, hairs 0.6-1.5 mm. Leaf-blade 3-15 cm × 2-12 mm, flat, soft, linear-lanceolate, tapered to fine tip, adaxially often with scattered long hairs, ribs and margins minutely scabrid. Culm 15-30-(100) cm, internodes ridged, scabrid above on ridges. Panicle 3.5-8.5-(11) cm × 5-15 mm, often drooping, ± cylindric, with light green to purplish, rather loosely, often irregularly clustered spikelets; rachis hispidulous-scabrid on ridges with very short, minutely scabrid branches bearing shortly pedicelled spikelets, each spikelet subtended by 1-2-(3) retrorsely scabrid bristles (2.5-5.5 mm). Spikelets 2-2.4 mm, falling entire at maturity. Lower glume 1-3-nerved, c. 1 mm, upper 5-7-nerved, ≈ spikelet, almost covering upper floret at maturity. Lower floret: lemma 5-7-nerved; palea hyaline, nerveless, to ½ length of lemma. Upper floret: lemma = spikelet, elliptic-oblong, subacute, pale cream, convex, thinly crustaceous, finely rugose; palea of same texture as lemma, keels not thickened, interkeel flat; anthers 0.6-0.9 mm; caryopsis c. 1.5 mm.
N.; S.: scattered throughout. Commonly a garden and crop weed (especially of maize in North Id), waste land, roadsides, footpaths.
Naturalised from Europe.
Plants which may be the hybrid S. verticillata × S. viridis were collected in Auckland City (CHR 391110) and in Marlborough at Blenheim (CHR 234839) and Renwicktown (CHR 224995). All three specimens have leaf-sheaths with ciliate margins, spike-like panicles with somewhat distant spikelets and 1-2 bristles below each spikelet; all have mature caryopses. The rachis is hispidulous, a character which distinguishes S. verticillata from S. viridis in which the rachis is pilose. However, the putative hybrids resemble S. viridis in their antrorsely scabrid bristles. The hybrid occurs naturally in southern Europe.
