Diplacrum

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 : 146

Diplacrum in Australia

Three species in Australia are apparently endemic ( Fig. 1 ), with only Diplacrum caricinum occurring more widely from Malesia to Japan, the Pacific, and India. Diplacrum exiguum (J.Kern) T.Koyama from Vietnam and D. pygmaeopsis from the Lesser Sunda Islands are not known from Australia, and we have seen no specimens of them. It is quite likely that the latter will be found in Australia, given the similarity of some habitats and the occurrence of many other sedge species in both of these regions.

Two or more of these tiny annual species may occur together, as shown by various mixed collections. They commonly grow in dense swards with other annual sedges on the damp margins of water-bodies.

Stamens are not obvious on most herbarium specimens because specimens tend to be collected when in fruit, at which stage the anthers have dropped and the male spikelets have withered, compressed by the expanding female spikelet above them, as noted by Bentham (1878) for D. pygmaeum .

Figures

Fig. 1. Distribution of Diplacrum species in Australia and Papua New Guinea based on data from the Australasian Virtual Herbarium (see https://avh.ala.org.au/, accessed June 2022). (a) D. caricinum. (b) D. blakei. (c) D. latzii. (d) D. pygmaeum.