Tetraria compar (L.) Lestib.

Elliott, T. L. & Muasya, A. M., 2017, Taxonomic realignment in the southern African Tetraria (Cyperaceae, tribe Schoeneae; Schoenus clade) *, South African Journal of Botany 112, pp. 354-360 : 357-358

6.2. Tetraria compar (L.) Lestib.– Tetraria picta (Boeckeler) C.B.Clarke and allies

Schoenus compar L. ( Fig. 2B ) ( Linnaeus, 1771) was transferred into Tetraria by T. Lestiboudois in 1819, who mentioned that the plant he based this decision on was collected by M. Du Petit-Thouars and was possibly the “ schoenus compar de Rottboëll ”. We assume that Lestiboudois erred in the designation of the authority of this species and should have attributed the name to earlier work by Linnaeus. This species is often viscoid, 50 cm to 1 m tall and has loose leaf sheaths as well as two-lobed ligules that are membranaceous ( Levyns, 1950). The spikelets are sessile or nearly so and are approximately 10 mm long with four to five empty lower glumes that are rigid and distichous ( Fig. 2G ) ( Clarke, 1900a; Levyns, 1950). The nutlet has three or four longitudinal ridges and is ovoid or globose in shape ( Levyns, 1950). Tetraria brachyphylla Levyns is a similar species; however, its leaves are shorter than those of T. compar (generally about 10 cm or less in length) and its sheaths are smooth and brownish-red ( Levyns, 1947). The inflorescence of T. brachyphylla generally has fewer spikelets than T. compar , while its nutlet beak is more continuous with the lower part of the fruit ( Levyns, 1947). Whereas T. compar is found on both dry slopes and more moist places in the fynbos, T. brachyphylla tends to be found in sandy, flat habitats and mountain slopes.

Tetraria picta (Boeckeler) C.B.Clarke is closely-related to T. compar ( Viljoen et al., 2013) , although it tends to be a smaller plant (200– 400 mm tall) with relatively short leaves and reddish-purple sheaths compared to the often white bases of T. compar ( Boeckeler, 1874) . The panicle of T. picta is contracted with inflorescence bracts that are dilated at the base ( Clarke, 1900a), so that they often envelope almost all of the spikelets. The compressed, elongate-oblong spikelets are in dense bundles and have chestnut-coloured, narrow, elongate-oblong, acute and keeled glumes ( Boeckeler, 1874; Clarke, 1900a). Tetraria sylvatica (Nees) C.B.Clarke var. pseudolorea Kük. appears similar, but it is generally taller, has a more elongate inflorescence, with bracts that are less dilated at the base. Both T. picta and T. sylvatica var. pseudolorea are found in high elevation fynbos in western South Africa ( Fig. 3B ).

Preliminary examination of herbarium specimens indicates that there are approximately five to ten morphospecies that could be placed in the T. compar – T. picta group.

Figures

Fig. 2. Examples of plants from each of the four clades of Schoenus found in southern Africa, showing the corresponding spikelets beneath each plant: A and F—S. nigricans, B and G—T.compar, C and H—Epischoenus sp. and D and I—T.cuspidata.A ‘reticulate-sheathed’ Tetraria of the Tricostularia clade is shown in E, with its spikelet shown in J.The black scale bar beneath the spikelets in F–J represents 1 mm.

Fig. 3. Documented locations of Schoenus nigricans and accepted southern African Tetraria and Epischoenus species in the Schoenus clade of Cyperaceae, based on data downloaded from GBIF (Copenhagen: Global Biodiversity Information Facility, 2014). The following groups of species are included in each map: A, S.nigricans; B, T. compar and allies; C,Epischoenus and allies; and D,T.cuspidata and allies. Schoenus nigricans has a cosmopolitan distribution (A), whereas the distribution of the other three groups is limited to southern Africa (B, C, and D).