Schoenus calceolus T.L.Elliott & Muasya, 2019

Elliott, T. L., Barrett, R. L. & Muasya, A. M., 2019, A taxonomic revision of Schoenus cuspidatus and allies (Cyperaceae, tribe Schoeneae) - Part 1 *, South African Journal of Botany 121, pp. 519-535 : 534-535

12. Schoenus calceolus T.L.Elliott & Muasya , sp. nov. Type: South Africa, Western Cape Province, 3420 (Bredasdorp): De Hoop Nature Reserve , 1 km S. of entrance gate on W. side of park, near start of bicycle trail, (–AD), 30 Sep 2016, Elliott & Muasya TE2016_121 ( BOL!, holo., MT!, NBG!, iso.) .

Caespitose, phyllopodic perennial graminoid. Culms terete, slender, 273–490 × 0.2–0.9 mm, culm bases flattened and held grouped together by a thin sheath. Leaves basal, distichously arranged so that base appears flat, 2–4(—7), (36–)65–115(—207) × 0.2–0.9 mm, straight, proximally channelled, margin serrate above sheath. Sheaths membranaceous and often shredding with age, loosely to firmly clasping the culm and translucent, longitudinally striate. Ligule firm, varying lengths, 0.2–2.7 mm long. In fl orescence a pseudolateral panicle, 19–40 × 4–11 mm, proximal rachis length 4–18 mm. Proximal primary in fl orescence bracts slender, brittle, not channelled, apex acute to acuminate, never widened at base, 60–112 mm long, exceeding length of inflorescence up to several times, without notable longitudinal veins. Proximal and subproximal primary inflorescence bracts never with membranaceous extensions at base. Spikes 3–11, 4.0–12.0 mm long, usually dispersed along rachis. Spikelets ovate, 2.4–4.0 × 1.1–1.4 mm, pedicellate, 2–8 spikelets per spike, reddish-brown sometimes with narrow hyaline margins. Proximal spikelet prophyll 1 per spikelet, prophylls with a raised vein extending to mucro, 0.3–1.3 mm long, prophyll mucro 0.8–2.4 mm long. Rachilla 0.4–2.8 mm long. Glumes 6–8 per spikelet, proximal glume 0.5–1.4 mm long, subproximal glume 0.5–1.3 mm long, upper glumes longer than basal ones, apex acute to acuminate. Glume mucros relatively short, proximal mucro 0.1–0.6 mm long, subproximal mucro 0.2–0.7 mm long. Stamens 3 per floret, anthers 1.9–3.3 mm long. Stigmas 3-branched, vestigial stigmas of second bisexual floret sometimes present. Perianth bristles not observed. Nutlet not mature on examined specimens ( Figs. 2 and 4 ).

Flowering: May

Distribution and ecology: The recorded specimens of S. calceolus have been collected from sites below 150 m in the southern Agulhas Plain region of South Africa ( Fig. 21 ). Schoenus calceolus mostly grows on limestone-derived soils; however, a specimen has been collected from a site on calcrete overlying shale.

Diagnosis: A unique character differentiating Schoenus calceolus from other species in this group is that its culm bases are flat (and sometimes twisted), with several culms grouped or held together by a thin translucent sheath ( Fig. 5 ). The spikelets of S. calceolus , S. prophyllus and S. purpurascens are all ovate; however, S. calceolus has slender, channelled leaves compared to the wider, often non-channelled leaves of S. purpurascens . Furthermore, S. prophyllus has firm, shiny prophylls and relatively long prophyll mucros (> 3.0 mm), whereas S. calceolus has less firm and not shiny prophylls, with shorter prophyll mucros (<2.4 mm).

Additional collections examined

South Africa. WESTERN CAPE: 3419 (Caledon): Spitzkop, W. of Baardskeerdersbos , (–DA), 26 Apr 1975, Oliver 5816 ( NBG, PRE) . 3420 (Bredasdorp): Vander Stelskraal , c. 500–1000 m S.E. of homestead, (–AC), 2 Oct 2016, Elliott & Muasya TE 2016_128 ( BOL) ; De Hoop Nature Reserve , coastal fynbos on limestone, (–AD), 6 Apr 1976, Burgers 147 ( NBG) ; De Hoop Nature Reserve , 5 km S. of gate, (–AD), 30 Sep 2016, Elliott & Muasya TE 2016_120 ( BOL) ; De Hoop Nature Reserve , 1 km S. of entrance gate on W.side of park, (–AD), 30 Sep 2016, Elliott & Muasya TE 2016_121 ( BOL) , Elliott & Muasya TE 2016_122 ( BOL) , Elliott & Muasya TE 2016_123 ( BOL) ; Duinefontein farm between Bredasdorp and Skipskop , near road, (–CB), 2 May 1981, Boucher 5035 ( NBG, PRE) .

Figures

Fig.2. Examples of nutlets from 11 species of the Schoenus cuspidatus and allies group found in southern Africa:A—S.auritus; B—S.graminifolius; C—S.ligulatus; D—S.exilis; E—S.bolusii; F— S.submarginalis; G—S.crassiculmis; H—S.quartziticus; I—S.limosus; J—S.purpurascens; and K—S.calceolus (immature).The black scale bar represents 1 mm.The mature fruits of S.calceolus and S.prophyllus are unknown.

Fig.4. Examples of plants from six species of the Schoenus cuspidatus andallies group found in southern Africa,showing the corresponding inflorescences and spikelets beneath each plant: A,G and M—S.crassiculmis; B,H and N—S.quartziticus, C,I andO—S.limosus; D,J,and P—S.purpurascens; E,K andQ—S.prophyllus; and F,L and R—S.calceolus. The black scale bar adjacent to the inflorescences in G—L represents 10 mm, while the scale bars adjacent to the spikelets in M—R represent 1 mm.

Fig. 21. Documented locations of Schoenus calceolus.

Fig. 5. Culm base of Schoenus calceolus showing culms grouped together by a translucent leaf sheath.The black scale bar adjacent to the base of the culms represents 10 mm.