Schoenus aureus T.L.Elliott & Muasya, 2018

Elliott, T. L. & Muasya, A. M., 2018, A taxonomic revision of Schoenus compar - Schoenus pictus and allies (Cyperaceae, tribe Schoeneae) with three new species described from South Africa *, South African Journal of Botany 114, pp. 303-315 : 312

5. Schoenus aureus T.L.Elliott & Muasya , sp. nov.

Type: South Africa, Western Cape Province, Worcester (3319): Klipbokkop Nature Reserve , (–CD), 25 May 2013, Muasya 6952 (BOL!, holo.; MT!, NBG!, iso.).

Caespitose, phyllopodic perennial graminoid with flat leaves. Not viscous. Culms terete, 450–602 × 0.7–1.0 mm. Leaves basal,2–4, flat, firm, not channelled, (11.5–)74.6–212.8(− 235.0) × 0.6–1.0 mm, up to or exceeding half of culm length, apices acute, margins serrate. Sheaths open, papery, ivory in colour, not viscous. Ligule membranaceous, long, 3.2–5.6 mm. In fl orescence a compact, short panicle, 15.0–28.0(− 38.5) × 4.5–7.0 mm, spikes usually overlapping, not viscous, golden to straw-coloured, proximal rachis length 6.0–16.0(− 20.0) mm. Proximal primary in fl orescence bracts flat, apices acute to acuminate, exceeding length of inflorescence, with membranaceous extensions along margins that cover part of spikes, lowest (64.5–)67.0–91.0(− 110.0) mm long. Spikes few, 2–3, congested, 7.0–14.0(− 27.0) mm long. Spikelets with pedicels, prophyll bracts with raised veins, oblong to lanceolate, (4.4–)5.2–6.7(− 7.2) × 1.2–2.2 mm, 3–7 spikelets/spike. Rachilla (0.8–) 1.5–2.2 mm long. Glumes 3–7 per spikelet, proximal glume (2.8–)4.0–5.6(− 6.2) mm long, subproximal glume 4.0–6.0(− 6.8) mm long, lower firm and shorter, upper thin and papery in texture, apices acute or acuminate. Mucros difficult to distinguish from glume apices, proximal mucro (0.1–) 0.4–1.7 mm long, subproximal mucro (0–)0.8–1.4(− 2.4) mm long. Stamens 3(− 4) per floret, anthers 4.0– 4.7 mm long. Stigmas 3-branched. Perianth bristles up to 6, shorter than or as long as glumes. Nutlet [only immature observed], 3-sided, wide elliptical, (1.8–)2.6–7.2 × 0.3–0.6(− 0.9) mm. Nutlet beak glabrous, conical, 0.6–1.0 mm long. ( Figs. 1 and 2 ). [Only immature nutlets from the Klipbokkop population were observed, most of which were broken during extraction due to being brittle towards the base. The anomalous two toned colouring shown in Fig. 2E was evident in all of the specimens from this location.].

Flowering: No flowering specimens observed

Distribution and ecology: To date, S. aureus has only been recorded in the Worcester area of South Africa growing among fynbos vegetation at altitudes ranging from approximately 400 to 1250 m ( Fig. 7 ).

Diagnosis: Schoenus aureus is a robust, relatively light coloured sedge, with ivory culm bases, long membraneous ligules and golden-brown glumes. The leaves and inflorescence bracts are flat, as in S.megacarpus — a species with a much larger nutlet. The compact panicle is similar in shape to that of S. compar and S. megacarpus ; however, S. compar lacks the wide marginal membraneous extensions on the inflorescence bracts. Schoenus megacarpus , on the other hand, has darker inflorescences than S. aureus and has more evident veins on the proximal primary inflorescence bracts. Mature nutlets have yet to be observed in this species.

Additional collections examined

South Africa. WESTERN CAPE: 3319 (Worcester): Fonteintjiesberg, (–CB), SE slopes, 26 Nov 1944, Esterhuysen 2942 (BOL); Blaaskloof, on W. slopes of the Keeromsberg, (–DA), 23 Feb 1958, Esterhuysen 27,588 (BOL, NBG).

Figures

Fig. 1. Examples of plants from each of the seven known species of S.compar - S.pictus group found in southern Africa, showing the corresponding inflorescences and spikelets beneath each plant:A,H and O—S.compar; B,I and P—S.arenicolus, C,J and Q—S.pictus; D,K,and R—S.pseudoloreus; E,L and S—S.aureus; F,M and T—S.megacarpus; and G,N and U—S.filiculmis. The black scale bar beside the inflorescences and spikelets in H—N represents 10 mm, whereas the scale bar beneath O—U represents 1 mm.

Fig. 2. Examples of nutlets from six species of the S. compar - S. pictus group found in southern Africa: A—S. compar; B—S. arenicolus; C—S. pictus; D—S. pseudoloreus; E—S.aureus (immature); and F—S. megacarpus. The black scale bar represents 1 mm.The mature fruit of S.filiculmis is unknown.

Fig. 7. Documented locations of Schoenus aureus.