Belongs within: Paniceae.
Pennisetum is a genus of grasses with spikelets subtended by an involucre of bristles (Gardner 1952).
Characters (Gardner 1952): Mostly perennials, rarely annuals; culms simple or often profusely branched; leaf-blade flat or convolute; ligule usually reduced to a ciliate rim or fringe of hairs, rarely membranous; inflorescence usually a dense spike-like panicle, branches numerous all round axis, very short and simple, with a solitary spikelet, or scantily divided with spikelets in clusters of two to five. Spikelets oblong or lanceolate in outline, subtended by, and deciduous with, involucre of bristles which are modified branchlets; bristles sessile or peduncled, simple, rarely branched, naked, scabrid or plumose, rarely reduced to 1. Florets 2; upper bisexual; lower, when present, male. Glumes usually small and hyaline; lower sometimes suppressed; upper rarely half as long as spikelet, or if longer then up to seven-nerved. Lemmas 2; lower equal and similar to upper, or more or less reduced and thinner and fewer-nerved, sometimes subtending to a male floret; upper membranous to chartaceous, five- to seven-nerved, subtending a bisexual floret. Paleas 2; lower subequal to its lemma or more or less reduced; upper subequal to its lemma and of similar texture, two-nerved. Lodicules 2, small, usually in front of and outside palea, or absent. Stamens 3, with tips of anthers glabrous or minutely penicillate. Styles slender, distinct or connate. Grain enclosed by more or less indurated lemma and palea, broadly oblong in outline, slightly dorsally compressed; hilum basal, punctiform; embryo large, more than half length of grain.
Pennisetum
|--P. alopecuroidesGPWG01
|--P. americanumM99
|--P. arnhemicumB78
|--P. basedowii Summerh. & Hubb. 1933G52
|--P. chilense [=Gymnothrix chilensis Desv. 1853]S06
|--P. clandestinum [incl. P. inclusum]G52
|--P. compressum [=Gymnothrix compressa, Setaria compressa]B78
|--P. dichotomumD17
|--P. divisumC00
|--P. elymoides (Muell.) Gardner 1952 [=Cenchrus elymoides]G52
| |--P. e. var. elymoidesLK14
| `--‘Cenchrus’ e. var. brevisetosusLK14
|--P. flaccidumO88
|--P. foermeranumCV06
|--P. glaucumGPWG01 (see below for synonymy)
|--P. hohenackeriS03
|--P. japonicum [=Gymnothrix japonica]B78
|--P. lanuginosumB78
|--P. macrourumBWA03
|--P. motanumS06
|--P. orientale Richard 1805PL04 [=P. setaceum ssp. orientalePL04; incl. P. ruppeliiG52]
|--P. pedicellatumB00
| |--P. p. ssp. pedicellatumLK14
| `--P. p. ssp. unispiculumLK14
|--P. polystachionK10
|--P. purpureumH06
|--P. rigidumS06
| |--P. r. var. rigidumS06
| `--P. r. var. longisetumS06
|--P. setaceumGPWG01
|--P. typhoides [=Alopecurus typhoides; incl. P. spicatum, P. typhoideum]G52
`--P. villosum Brown 1837S06 [incl. P. longistylumG52]
Pennisetum glaucumGPWG01 [=Panicum glaucum Lin. 1753B78, S06, Chaetochloa glauca (Lin.) Scribn. 1897S06, Chamaeraphis glauca OK. 1791S06, Ixophorus glaucus Nash 1895S06, Setaria glauca (Lin.) Beauv. 1812S06; incl. Panicum lutescensG52, S. lutescensV72]
*Type species of generic name indicated
References
[BWA03] Beard, J. J., D. E. Walter & P. G. Allsopp. 2003. Spider mites of sugarcane in Australia: a review of grass-feeding Oligonychus Berlese (Acari: Prostigmata: Tetranychidae). Australian Journal of Entomology 42: 51–78.
[B78] Bentham, G. 1878. Flora Australiensis: A description of the plants of the Australian Territory vol. 7. Roxburghiaceae to Filices. L. Reeve & Co.: London.
[B00] Braby, M. F. 2000. Butterflies of Australia: their identification, biology and distribution vol. 1. CSIRO Publishing: Collingwood (Victoria).
[CV06] Craven, P., & P. Vorster. 2006. Patterns of plant diversity and endemism in Namibia. Bothalia 36 (2): 175–189.
[C00] Cunningham, P. 2000. Daily activity pattern and diet of a population of the spiny-tailed lizard, Uromastyx aegyptius microlepis, during summer in the United Arab Emirates. Zoology in the Middle East 21: 37–46.
[D17] Diels, L. 1917. Beiträge zur Flora der Zentral-Sahara und ihrer Pflanzengeographie. Nach der Sammelausbeute des Freiherrn Hans Geyr von Schweppenburg. Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie 54 (Beiblatt 120): 51–155.
[G52] Gardner, C. A. 1952. Flora of Western Australia vol. 1 pt 1. Gramineae. William H. Wyatt: Perth.
[GPWG01] Grass Phylogeny Working Group. 2001. Phylogeny and subfamilial classification of the grasses (Poaceae). Annals of the Missouri Botanical Garden 88 (3): 373–457.
[H06] Henderson, L. 2006. Comparisons of invasive plants in southern Africa originating from southern temperate, northern temperate and tropical regions. Bothalia 36 (2): 201–222.
[K10] Keighery, G. 2010. The naturalised vascular plants of the Pilbara region, Western Australia. Records of the Western Australian Museum Supplement 78 (1): 299–311.
[LK14] Lyons, M. N., G. J. Keighery, L. A. Gibson & T. Handasyde. 2014. Flora and vegetation communities of selected islands off the Kimberley coast of Western Australia. Records of the Western Australian Museum Supplement 81: 205–244.
[M99] Matthews, M. 1999. Heliothine Moths of Australia: A guide to bollworms and related noctuid groups. CSIRO Publishing.
[O88] Ohba, H. 1988. The alpine flora of the Nepal Himalayas: an introductory note. In: Ohba, H., & S. B. Malla (eds) The Himalayan Plants vol. 1. The University Museum, University of Tokyo, Bulletin 31: 19–46.
[PL04] Pohl, G., & I. Lenski. 2004. Zur Verbreitung und Vergesellschaftung von Pennisetum orientale Rich. in Nordeuböa (Griechenland) (Poaceae, Paniceae). Senckenbergiana Biologica 83 (2): 209–223.
[S03] Singh, J. N. 2003. Grasses and their hydro-edaphic characteristics in the grassland habitat of Nilgiris Biosphere Reserve, Tamil Nadu. Bulletin of the Botanical Survey of India 45: 143–164.
[S06] Stuckert, T. 1906. Segunda contribución al conocimiento de las gramináceas Argentinas. Anales del Museo Nacional de Buenos Aires, serie 3, 6: 409–555.
[V72] Voss, E. G. 1972. Michigan Flora. Part I. Gymnosperms and Monocots. Cranbrook Institute of Science and University of Michigan Herbarium.