Isolepis R.Br. (Brown 1810: 221)

Rasaminirina, Fitiavana & Larridon, Isabel, 2023, The genera of Cyperaceae of Madagascar, Plant Ecology and Evolution 156 (3), pp. 276-310 : 276

1. Isolepis R.Br. (Brown 1810: 221)

Type species.

Scirpus setaceus L. [= Isolepis setacea (L.) R.Br.]

Description of the genus.

Small to more rarely medium-sized tufted annuals or mat-forming perennials; rhizome more rarely creeping, rhizomatous or stoloniferous. Culms scapose or with few to many nodes. Leaves eligulate, of a minute lobe or elongated to form a linear blade often much reduced. Primary bracts leaf-like or short, not sheathing, lowermost bract often erect. Inflorescence often pseudolateral, capitate, rarely anthelate. Spikelets few to many or reduced to a single spikelet. Glumes with few to many usually spirally arranged (rarely distichous), mostly deciduous glumes, each subtending a floret. Floret bisexual. Perianth bristles absent. Stamens 1-3; filament ribbon-like, anther crested with minute spikes. Style deeply 2-3-fid; base not distinct, not or slightly thickened, persistent. Nutlets mostly obovoid, thick lenticular to (rounded) trigonous, often 3-ribbed, beaked, surface with various ornamentations.

Distribution and ecology.

Isolepis is a cosmopolitan genus ( POWO 2022). It grows in temporary and permanently wet areas. In Madagascar, Isolepis is known from the north and the Central Highlands; four species are known including e.g. Isolepis fluitans (L.) R.Br. (Fig. 21 ).

Figures

Figure 21. Isolepis fluitans. A. Habit. B. Leaf sheath. C. Spikelet. D. Rachilla, apical glume attached. E. Glume, lateral view. F. Floret. G, H. Nutlet, abaxial and apical view. All from Iversen & Martinsson 89195. Scale bars: A = 40 mm; B-H = 1 mm. Drawn by Jane Browning, reproduced with permission from the artist, originally published in Browning et al. (2020).