Oplismenus is a small genus of annual or perennial grasses found throughout the tropics of the Americas, Africa, Asia, and Australia. The systematics of the genus are unclear, and between five and nine species are recognised.
The French naturalist Palisot de Beauvois described the genus in August or September of 1810 in his Flore d'Oware et de Benin. At a later date, however, it was noted that Robert Brown had also defined the genus earlier the same year, as Orthopogon, in his work Prodromus Florae Novae Hollandiae. Nevertheless, because the name Oplismenus had been universally used for many years, it was ruled a nomen conservandum (conserved name) in 1978. The generic name is derived from the Ancient Greek hoplismenos ("armed"), because the glumes have awns.
The number of species is unclear, with some disagreement among botanists. In Australia, Oplismenus aemulus and O. imbecillis are recognised as separate species by the Queensland and New South Wales Herbaria, but not by the National Herbarium, which classifies them as synonyms of O. hirtellus.
A multiple discriminant analysis published in 1978 of the characteristics used to define the species of Oplismenus worldwide found a high degree of overlap in Australia, indicating O. aemulus and O. imbecilis fell within the parameters of O. hirtellus, as did the American taxon O. setarius. The other American taxon, O. rariflorus, fell within O. compositus. The authors proposed the recognition of only five species:
- Oplismenus burmannii - pantropical
- Oplismenus thwaitesii - Sri Lanka (may be synonymous with O. burmannii)
- Oplismenus compositus - Americas, Africa, Asia, Australia, Pacific
- Oplismenus hirtellus - tropics, but replaced in India and Indochina by O. compositus
- Oplismenus undulatifolius - widespread
The German botanist Ursula Scholz published a monograph in 1981, having studied the genus throughout the world and examined over five thousand specimens, including 61 type specimens. She recognized nine species and 18 infraspecific taxa.
- Section Scabriseta
- O. affinis Schult.
- O. affinis var. affinis
- O. affinis var. humboldtianus
- O. baronii
- O. burmannii
- O. burmannii var. burmannii
- O. burmannii var. lanatus
- O. burmannii var. multisetus
- O. flavicomus
- O. gracillimus
- O. humbertianus
- O. affinis Schult.
- Section Oplismenus
- O. aemulus
- O. aemulus var. aemulus
- O. aemulus var. flaccidus
- O. aemulus var. densiflorus
- O. compositus
- O. compositus var. compositus
- O. compositus var. rariflorus
- O. compositus var. sylvaticus
- O. hirtellus
- O. hirtellus subsp. hirtellus
- O. hirtellus subsp. acuminatus
- O. hirtellus subsp. capensis
- O. hirtellus subsp. fasciculatus
- O. hirtellus subsp. imbecillis
- O. hirtellus subsp. japonicus
- O. hirtellus subsp. microphyllus
- O. hirtellus subsp. psilostachys
- O. hirtellus subsp. setarius
- O. hirtellus subsp. tsushimensis
- O. hirtellus subsp. undulatifolius
- O. aemulus
The members of this genus are scrambling or trailing herbaceous grasses, both annual and perennial. The stems trail along the ground and can root at the nodes. The leaf blades are generally lance-shaped or acuminate to ovate and are covered in scattered hairs, and the leaf sheaths are hairy.
These are generally plants of shady areas such as the forest floor. They commonly die off in cooler or drier months. Some species have invasive potential. Unlike some of their relatives, members of this genus use C3 photosynthesis.
Variegated forms have been cultivated as house plants in Europe. Locally occurring species in Australia have been used for revegetation and reclamation in shady or wet areas, though some can be invasive. Some have been promoted as local native plants for wildlife gardens, and as lawn grass. They are edible to livestock.
- Kew World Checklist of Selected Plant Families
- Tropicos, Orthopogon R. Br.
- Palisot de Beauvois, Ambroise Marie François Joseph. 1810. Flore d'Oware et de Benin en Afrique 2: 14, pl. 68, f. 1.
- "Oplismenus P.Beauv. [ nom. cons. ]". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government.
- "Orthopogon R.Br.". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government.
- Scholz, Ursula (1981). Monograph of the genus Oplismenus (Gramineae) (PDF). Hirschberg: Strauss & Cramer GmbH. ISBN 3-7682-1292-0.
- Bussmann, R. W., et al. (2006). Plant use of the Maasai of Sekenani Valley, Maasai Mara, Kenya. J Ethnobiol Ethnomed 2 22.
- USDA Plants Profile: Oplismenus
- "Oplismenus hirtellus (L.) P.Beauv.". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government.
- Davey, J. C.; Clayton, W. D. (1978). "Some multiple discriminant function studies on Oplismenus (Gramineae)". Kew Bulletin 33 (1): 147–57. JSTOR 4110116.
- Elliot, Rodger W.; Jones, David L.; Blake, Trevor (1997). Encyclopaedia of Australian Plants Suitable for Cultivation:Volume 7 – N-Po. Port Melbourne: Lothian Press. pp. 106–07. ISBN 0-85091-634-8.
- Quattrocchi, Umberto (2006). CRC World Dictionary of Grasses: Common Names, Scientific Names, Eponyms, Synonyms, and Etymology, Volume 1. CRC Press. pp. 1410–11. ISBN 0-8493-1303-1.
- Seidenberg, Charlotte (1995). The Wildlife Garden: Planning Backyard Habitats. Univ. Press of Mississippi. p. 200. ISBN 0-87805-835-4.
- Daniels, Stevie (1999). Easy Lawns: Low Maintenance Native Grasses for Gardeners Everywhere. Brooklyn Botanic Garden. p. 68. ISBN 1-889538-12-4.