Diplacrum R.Br., Prodr.

Wilson, Karen L. & Barrett, Russell L., 2023, Revision of the tropical genus Diplacrum (Cyperaceae: Bisboeckelereae) in Australia, Australian Systematic Botany 36 (2), pp. 143-156 : 144-145

Diplacrum R.Br., Prodr. 240 (1810)

Scleria sect. Diplacrum (R.Br.) Kern , Blumea 11(1): 208 (1961). Type: D. caricinum R.Br.

Pteroscleria Nees , in C.F.P. von Martius, Fl. Bras. 2(1): 196 (1842). Type: P. guianensis Nees.

Sphaeropus Boeckeler , Flora 56: 89 (1873); Scleria sect. Sphaeropus (Boeckeler) J.Kern , Blumea 11(1): 208 (1961). Type: S. pygmaeu s Boeckeler.

Small or dwarf annuals with reddish roots (rarely slender stoloniferous perennials). Culms tufted. Leaves basal and cauline, flat, without a ligule or contraligule. Inflorescence capitate, or branched with several small, dense clusters of spikelets, or spikelet clusters axillary at the remote nodes of a more elongated inflorescence axis. Primary involucral bracts leaf-like. Lateral spikelets in a cluster male, 0‒2; terminal spikelet female. Male spikelets with 1 persistent glume, each subtending 1 male flower; stamen 1(3). Female spikelets on a peduncle usually thickened at the apex at maturity, often strongly so and disc- or cup-like; glumes 2, distichous, keeled or not, persistent or deciduous with the fruit, encircling a (?)pseudo-terminal female flower; style 3-fid; style base deciduous, not thickened. Disc usually triangular, adhering to nutlet, usually paler. Nutlet subglobose to ovoid or narrow–obovoid, terete to trigonous in cross-section, inconspicuously 3-angled, surface glabrous or sparsely puberulous near the apex, otherwise smooth or longitudinally ribbed or reticulate, falling freely or enclosed by the persistent, thickened glumes.

This description covers the features of Diplacrum sens . strict. as well as the three species sometimes referred to the genus Pteroscleria (see discussion above). The features of the latter are given in parentheses where they differ from those of the former.

Key to Diplacrum species in Australia, Malesia