PlantaeDB Logo
Login Sign-up

Genus Oplismenus in Family Poaceae

In botanical taxonomy, a genus (plural genera) is a rank used to group closely related species within a family. In the hierarchy, genus sits below family and above species.

Genera are defined by shared morphological, anatomical, and genetic characteristics (for example, features of flowers, fruits, seeds, or leaves) that indicate a close evolutionary relationship among the species they contain.

Each genus can include one or more species. Examples include Rosa (roses) and Solanum (nightshades, including tomato and eggplant).

Do you wish to read more about plant taxonomy? Click here!

Genus Description

Suggest a correction!

Oplismenus (author abbreviation P.Beauv.), a genus in Poaceae (subfamily Panicoideae, tribe Paniceae), comprises roughly 10–15 species of small, shade‑tolerant grasses with a broad pantropical distribution extending into warm‑temperate regions. In Poaceae, the type species is typically the one originally designated by the author; Oplismenus burmannii is treated as the type by several recent floras and databases (POWO, 2024; WFO, 2024).

Plants are weak, prostrate to ascending annuals or perennials, often rooting at nodes. Culms are slender and may be rooting along the ground. Blades are usually lanceolate to ovate with membranous ligules; indumentum varies from glabrous to pubescent, and nodes may bear short hairs. The inflorescence consists of one to several weak, spreading racemes bearing paired spikelets; spikelets are dorsally compressed, the lower glume is small and sometimes absent, and at least one of the lemmas bears a prominent awn. Disarticulation occurs at maturity, with the lower glume typically falling with the floret. Caryopsis have a linear hilum and a starchy pericarp typical of Paniceae.

Diversity and range center in tropical Asia and Africa, with additional taxa in Australasia and the Neotropics. Most species favor moist, shaded forest floors, stream margins, and other mesic microsites at low to mid elevations; a few extend into disturbed or weedy habitats. Patterns reflect Old World origins with independent dispersals into the Americas and Australasia.

Pollination is predominantly wind‑mediated, typical of Paniceae, but specialized biotic pollination has not been documented for this genus. Fruit dispersal is passive, via dehiscence and subsequent caryopsis movement by gravity, water, or animal vectors. Chromosome numbers have been reported as x = 9 in several Paniceae, though specific counts for individual Oplismenus taxa vary in the literature and are not consistently verified across species (POWO, 2024).

Taxonomically, Oplismenus has been broadly circumscribed but is now treated conservatively within tribe Paniceae. It was historically placed in subtribe Boivinellinae and is closely aligned with Panicum, Entolasia, and relatives based on morphology and recent phylogenetic syntheses of Paniceae (Morrone et al., 2020). Some historical segregates, especially Pseudostachys, are largely reduced to synonymy in current checklists, though alternative treatments persist locally (WFO, 2024). Species limits remain unstable in several Old World taxa.

Human relevance includes limited horticultural use for shade‑tolerant groundcovers in tropical gardens and some species act as minor weeds in cultivated or disturbed sites. No major food or timber species are recognized.

Conservation concerns are unevenly documented; several narrow endemics remain poorly assessed, and habitat loss in lowland forests poses a general threat. Priority research includes resolving species circumscription and updating IUCN assessments for data‑deficient taxa.

Pick a Species to see its components: