Volume V (2000) - Flora of New Zealand Gramineae
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Pennisetum Rich.

Pennisetum Rich., 1805

Type species: P. typhoideum Rich.  nom. illeg.

Tufted or rhizomatous or straggling perennials; or annuals. Leaf-sheath loose, usually open. Ligule usually a ciliate rim, rarely membranous. Leaf-blade linear to lanceolate, flat, folded or convolute. Culm simple or much-branched. Inflorescence usually a dense, spike-like panicle with very numerous, very short branches falling with spikelets at maturity, and usually leaving scars on the rachis; rarely reduced to a few spikelets. Spikelets 2-flowered, solitary or in groups of 2 or 3 surrounded by an involucre of unequal glabrous or plumose bristles united at base; spikelets and bristles shed freely at maturity; lower floret ♂ or Ø, with or without palea, rarely ⚥; upper floret ⚥, or sometimes ♂ in lateral spikelets of a cluster. Glumes membranous, subequal, or the lower smaller, sometimes minute or 0; lower (0)-1-3-nerved, upper ≤ spikelet, (0)-1-9-nerved. Lower floret: lemma ≤ spikelet, membranous, (0)-3-9-(15)-nerved, enclosing narrow palea, or palea 0. Upper floret: lemma ≈ spikelet, chartaceous, (3)-5-7-(15)-nerved, glabrous or sometimes pubescent near margins; palea ≈ lemma and of similar texture; lodicules minute or 0; stamens 3, anthers occasionally penicillate; ovary apex glabrous, styles ± terminal, free or ± connate; caryopsis dorsiventrally compressed, embryo large, hilum punctiform.

Key

1
Forming large patches or semiscandent; inflorescence of (1)-2-4 spikelets included (except at anthesis) within uppermost leaf-sheath on short branches
Forming erect tufts, clumps, or tussocks; inflorescence of many spikelets in a conspicuous spike-like or compound panicle
2
2
Involucral bristles short-scabrid
3
Involucral bristles plumose throughout, below, or on inner only
5
3
Leaf-sheaths usually with conspicuous cross-veinlets; inflorescence a compound panicle with clusters of long-pedunculate spikes from axils of upper culm leaves
Leaf-sheaths without conspicuous cross-veinlets; inflorescence a simple spike-like panicle
4
4
Panicle (16)-20-40 cm; involucral bristles ≥ spikelets and 6-10 mm, with a single stouter bristle to 15-(20) mm
Panicle 7-12 cm; involucral bristles » spikelets, 15-25 mm
5
Panicle usually subglobose, usually pale green or silvery; spikelets 8-11 mm
Panicle cylindric, usually tinged reddish purple; spikelets 5-7.5 mm
6
6
Involucral bristles < spikelets; plants annual
Involucral bristles > spikelets; plants perennial
7
7
Leaf-blade 0.5-1.5 mm wide, folded or ± involute; involucral bristles 15-25 mm, a single longer bristle to 35 mm
Leaf-blade 20-30 mm wide, flat; most involucral bristles c. 10 mm, a single stouter bristle to 20 mm

c. 130 spp. of tropical and warm temperate regions. Naturalised spp. 7; transient sp. 1.

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