Tetraria is a genus of perennial herbs belonging to the sedge family, Cyperaceae, placed in the order Poales. The genus encompasses around 40 accepted species distributed across a broad Southern Hemisphere range, with centres of diversity in South Africa and extending to Tanzania, Borneo, Australia, and New Zealand.
Plants in this genus are characterised by their generally few-noded stems and leaves that are conspicuously sheathed, bearing flat or inward-curving blades. The inflorescence is typically a narrow panicle. Individual flowers are bisexual, though the lower flowers in each spikelet tend to be male; most species bear three stamens and three stigmas. The fruit is a nutlet, usually trigonous (three-angled) in cross-section and often retaining its persistent style as a beak or crown-like projection at the apex.
The generic name Tetraria is associated with the type species Tetraria compar (L.) P.Beauv. Recent molecular phylogenetic studies have demonstrated that Tetraria as traditionally circumscribed is polyphyletic — meaning it does not form a single natural lineage — and that taxonomic revision is needed. Some species formerly included in Tetraria have already been transferred to other genera through ongoing revisionary work.
Distribution
The genus is native to South Africa (where most diversity is concentrated), Tanzania, Borneo, Australia, and New Zealand, reflecting a broad Southern Hemisphere and Indo-Pacific distribution.
Taxonomy Notes
Tetraria as traditionally circumscribed has been shown by recent molecular work to be polyphyletic, meaning its species do not form a single exclusive lineage. Revisionary studies have led to transfers of some species to other genera, and further reclassification is expected. The type species is Tetraria compar (L.) P.Beauv.
