PlantaeDB Logo
Login Sign-up

Genus Isachne 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!

The grass genus Isachne (R.Br.) belongs to the family Poaceae, subfamily Panicoideae, tribe Arundinelleae. Plants of the World Online (POWO, 2024) and the World Flora Online (WFO, 2024) list approximately 150 accepted species, which are distributed across tropical and subtropical regions of Africa, Asia, Australia, and the Americas. The lectotype for the genus is Isachne australis R.Br., fixed by Hitchcock in 1911 (POWO, 2024).

Species are caespitose or rhizomatous perennials, occasionally annual, bearing linear leaf blades that are flat or folded, often with scabrid margins and a membranous, ciliate ligule; true stipules are absent. The inflorescence is an open panicle, sometimes contracted, bearing numerous small, dorsally compressed spikelets that typically contain two similar florets; lemmas and paleae are awnless and nearly equal, with a prominent median ridge. The ovary is superior, unilocular, bearing a single basal ovule, and the fruit is a small caryopsis with a fused pericarp (Kellogg, 2015).

The highest species richness occurs in East Africa, Southeast Asia and northern Australia, with several narrowly endemic taxa in Madagascar and New Guinea. Plants occupy open grasslands, savannas, marshes, riverbanks and secondary growth, ranging from sea level to about 2 000 m elevation; most are tied to moist to wet habitats, while a few occur in drier woodlands (POWO, 2024; WFO, 2024).

As in most Poaceae, Isachne is wind‑pollinated, and the minute caryopses are dispersed by water, animals or wind; many wetland species exhibit hydrochory. Chromosome counts consistently indicate a base number of x = 9 (2n = 36, 54) across the genus (Kellogg, 2015).

Current molecular phylogenies place Isachne firmly within Arundinelleae, sister to the clade containing Loudetia and Tristachya (GPWG, 2021; Huang et al., 2020). The genus is not formally subdivided, but several species have been transferred to related genera; for example, Isachne nutans is now treated as Axonopus nutans (GPWG, 2021). Some earlier treatments placed the genus in subtribe Isachneae of tribe Poeae, but plastid and nuclear data support the Arundinelleae placement (GPWG, 2021).

Only a handful of species, notably Isachne globosa and Isachne australis, are used as ornamental grasses in temperate gardens for their delicate panicles; other taxa act as modest weeds in pastures and rice fields, especially in South Asia.

Habitat conversion and wetland drainage threaten several narrow endemics, and many taxa remain data‑deficient; targeted field surveys and integrative taxonomy are needed to assess extinction risk and guide conservation (POWO, 2024).

Pick a Species to see its components: