Pennisetum purpureum Schumach.
elephant grass
Robust tufted perennial to 3 m or more, from stout rhizome to 6 mm diam. Leaf-sheath with fine ± appressed hairs. Ligule densely ciliate, hairs to 3 mm. Leaf-blade 30-75 × 2-3 cm, flat, with numerous fine appressed hairs. Culm internodes with fine hairs for some distance below inflorescence and long soft retrorse hairs above nodes. Panicle c. 14 × 2 cm, cylindric, spike-like with densely crowded spikelets; rachis villous. Spikelets 6.5-7.5 mm, solitary or in clusters of up to 5, straw-coloured, tinged reddish purple; involucre of numerous fine minutely scabrid bristles (c. 10 mm), some bristles plumose below and one much stouter and longer (to 20 mm). Lower glume 0, or minute, upper 0.5-1 mm, nerveless or 1-nerved, acute. Lower floret Ø: lemma < spikelet, 1-3-nerved, lanceolate, acute to acuminate; palea 0. Upper floret ⚥: lemma = spikelet, 5-nerved, glabrous, acuminate; palea ≈ lemma and of similar texture; anthers c. 3 mm, penicillate; gynoecium: ovary 1-1.5 mm, stigma-styles to 9.5 mm; caryopsis not seen.
N.: North Auckland (Lake Tangonge, Ahipara, Waiharara). Escape from cultivation; on roadsides.
Naturalised from tropical Africa.
The lower floret in P. purpureum is usually described as ♂ or Ø, ≤ spikelet, and with or without a palea, e.g., Vickery, J. W. Fl. N.S.W. No. 19, Gramineae 2: 246-247 (1975); but in the very few specimens examined from the wild the lower floret was Ø, ≤ spikelet, and without palea.
