Schoenus adnatus (Levyns) T.L.Elliott & Muasya

Elliott, T. L. & Muasya, A. M., 2020, A taxonomic revision of the Epischoenus group of Schoenus (Cyperaceae, tribe Schoeneae), South African Journal of Botany 135, pp. 296-316 : 310

7. Schoenus adnatus (Levyns) T.L.Elliott & Muasya , S. African J. Bot. 112: 359 (2017).

Epischoenus adnatus Levyns, J. S. African Bot. 13: 54 (1947).

Type: South Africa, Western Cape Province, 3318 (Cape Town): Ferny Gully on the eastern slopes of Table Mountain , (‒CD), 12 Aug 1946, Esterhuysen 12,938 ( BOL, holo! [ BOL_139403 ]; BOL! [ BOL_150138 ], BOL [ BOL_139404 ] — image!, K [ K000244896 ] — image!, NBG! [ NBG0024996-1 , NBG0024996-2 ], PRE [ PRE0099596-0 ] — image!, iso.) .

Tetraria gracilis Turrill , Bull. Misc. Inform. Kew 1925: 73 — 74 (1925). Schoenus tenuellus T.L.Elliott & Muasya , S. African J. Bot. 112: 359 (2017) , non Schoenus gracilis Sw. (1788) .

Type: South Africa, Eastern Cape Province, 3324 (Steytlerville): Uniondale division, S side of the Blaauw Bosch Pass, (‒BD), Nov 1923, Fourcade 2816 (K [K000244898], lecto. — image!, here designated; BOL [BOL_139427, BOL_139428] — image!, GRA! [GRA0000236-0], K [K00024497] — image!, isolecto). [Note: As Turrill (1925) did not specify a holotype for this taxon, we have designated one of the specimens stored at K as the lectotype, since Turrill worked at that institution.].

Caespitose, perennial graminoid, aphyllopodic, culms ridged ( Fig. 4B and H ). Culms narrow, (255 —)410 — 568(‒705) £ 0.2 — 0.5 mm. Leaves absent. Sheaths reddish-brown, longitudinally striate, open, central vein terminating in a mucro up to several mm long, semi-firm to firm. Ligule 0.2‒1.7(‒4.1) mm. In fl orescence a pseudolateral panicle with few, dispersed spikelets, (6 —)9‒16(‒20) £ 3.0‒5.0(‒6.0) mm, proximal rachis length 3.0‒8.0(‒9.0) mm ( Figs. 4H and 7G ). Proximal primary in fl orescence bracts (9 —)14‒28(‒37) mm long, narrow, without lateral chartaceous extensions, varying from involute to terete distally, apex acute but breaking-off readily, exceeding length of inflorescence slightly. Spikes 1‒2 (usually 2), 6‒9(‒15) mm long, aggregated into small clusters along rachis, slightly overlapping. Spikelets lanceolate to ovate, 1 — 2 (usually 2) spikelets per spike, (4.5 —) 5.1‒6.0(‒7.4) £ (1.0 —) 1.4‒1.7 mm, pedicellate, colour reddish-brown, texture firm and opaque, not concealed by primary inflorescence bracts, varying number of sterile glumes at spikelet base ( Fig. 8G ). Proximal spikelet prophyll sometimes present, (0.6 —)0.9‒1.7(‒2.9) mm, mucros 0‒0.7(‒1.6) mm long when present. Rachilla (0.2‒)0.7‒ 2.1(‒4.0) mm long. Glumes 5‒8 per spikelet, texture opaque and firm, narrow hyaline margins, lower glumes relatively short, proximal glume (0.7‒)1.0‒1.3(‒1.9) mm long, subproximal glume (1.1‒)1.4‒2.1 (‒2.4) mm long, upper glumes longer than basal ones, apex acuminate to obtuse. Glume mucros often absent, proximal mucro 0‒0.1(‒ 1.0) mm long, subproximal mucro 0‒0.6 mm long. Stamens 3 per floret, anthers (1.5‒)1.8‒3.0(‒3.4) mm long. Stigmas 2 — 3-branched, vestigial stigmas present. Perianth bristles absent (i.e. yet to be observed). Suprafloral axis sometimes thickening and strengthening, eventually curving. Nutlet 1.7‒2.3(‒2.7) £ 1.1‒1.4 mm, broad elliptic, weakly trigonous, shiny, yellowish in colour when young and turning dark reddish black with maturity, sessile; nutlet beak narrow, 0.1‒ 0.3 mm ( Fig. 10G ). ( Figs. 4 , 7 , 8 and 10 )

Flowering: September to April

Distribution and ecology: The distribution of S. adnatus spans from the Steytlerville region in the Eastern Cape Province of South Africa to the Cape Peninsula in the Western Cape Province ( Fig. 17 ). It is a primarily mountainous species that has been collected from both moist and dry sites from elevations ranging between 450 — 1375 m.

Diagnosis: The key diagnostic character of S. adnatus is that the spikelet receptacle is adnate to the basal glume (see Fig. 9A ). Schoenus gracillimus and S. schonlandii are the two species that are most similar in growth form; however, the spikelet receptacles of both these species do not exhibit this character. Although a few hairs have been observed on a couple of S. adnatus specimens, its spikelets and culms are much less hairy than those of S. crinitus . Furthermore, the culms of S. adnatus are narrower (± 5mm) than those of S. crinitus (Ŀ 6mm).

Additional collections examined

South Africa. EASTERN CAPE: 3323 (Willowmore): Lauterwater , (‒DC), 1 Jan 1940, Stokoe s.n. ( SAM) . WESTERN CAPE: 3318 (Cape Town): Table Mt. , SE slopes above Newlands , below Ferny Dell , (‒ CD), 17 Feb 1946, Esterhuysen 12,629 ( BOL [2 sheets], NBG) ; E slopes of Table Mtn. above Newlands , Hiddingh Buttress , (‒CD), 19 Feb 1950, Esterhuysen 16,809 ( BOL, GRA, PRE, SAM) ; rocky slopes near head of Jonkershoek valley , (‒DD), 3 Apr 1949, Esterhuysen 15,222 ( BOL [2 sheets], GRA, NBG, SAM) ; Jonkershoek Twins , (‒DD), 8 Apr 1951, Esterhuysen 18,489 ( BOL) ; 23 Oct 1973, Esterhuysen 33,275 ( BOL) . 3319 (Worcester): cliffs below shale band on E side of Milner Pk. , Hex R. Mts. , (‒AD), 18 Dec 1948, Esterhuysen 14,863 ( BOL [2 sheets], SAM [2 sheets]) ; mountains above Du Toit's Kloof , (‒CA), Apr 1932, Stokoe s.n. ( BOL [2 sheets]) ; kloof between Witteberg and Molenaarsberg, above Du Toits Kloof , (‒CA), 28 Aug 1949, Esterhuysen 15,679 ( BOL) ; 20 Jun 1959, Esterhuysen 28,302 ( BOL) ; steep rocky slopes on S side of Upper Wellington Sneeuwkop , (‒CA), 27 Sep 1953, Esterhuysen 21,784 ( BOL) ; Jonkershoek valley, along the Contour Path below the 3rd Ridge Pk., (‒CC), 10 Jan 1973, Esterhuysen 33,112 (BOL, PRE). 3320 (Montagu): Heidelberg, outskirts of Boesmansbos Grootvadersbosch Forest Reserve, (‒DD), 21 Mar 1962, Taylor 3225 ( NBG) .

Figures

Fig. 4. Examples of plants from six species of the Epischoenus group found in southern Africa, showing the corresponding inflorescences beneath each plant: A and G—S.crinitus; B and H—S. adnatus; C and I—S. gracillimus; D and J—S. schonlandii; E and K—S. lucidus; and F and L—S. neovillosus. The black scale bar adjacent to the inflorescence in L represents 10 mm.

Fig. 7. Diagrammatic representations of the inflorescences of 11 species in the Epischoenus group, with spikelets illustrated in dark grey, primary inflorescence bracts in white and chartaceous (membranaceous) lateral extensions of the primary inflorescence bracts in light grey. Illustrations are not drawn to exact scale and stippling represents hairs. Inflorescences of the following species are shown: A—S. dregeanus; B—S. complanatus; C—S. quadrangularis; D—S. selinae; E—S. rigidus; F—S. crinitus; G—S. adnatus; H—S. gracillimus; I—S. schonlandii; J—S. lucidus; and K—S.neovillosus.

Fig. 8. Examples of spikelets from 11 species of the Epischoenus group found in southern Africa: A—S.dregeanus; B—S.complanatus; C—S. quadrangularis; D—S. selinae; E—S.rigidus; F—S.crinitus; G—S.adnatus; H—S.gracillimus; I—S.schonlandii; J—S.lucidus; and K—S.neovillosus. The black scale bar beside K represents 1 mm.

Fig. 10. Examples of nutlets from 11 species of the Epischoenus group found in southern Africa: A—S. dregeanus; B—S.complanatus; C—S. quadrangularis; D—S. selinae; E—S.rigidus; F—S.crinitus; G—S.adnatus; H—S.gracillimus; I—S.schonlandii; J—S.lucidus; and K—S.neovillosus. The black scale bar beside K represents 1 mm. Fully formed, mature nutlets of S.crinitus and S. neovillosus have yet to be observed.

Fig. 17. Documented locations of S.adnatus.

Fig. 9. Spikelet of S.adnatus (A) showing the spikelet receptacle adnate to the proximal glume contrasted with the spikelet of S.crinitus (B), which shows the typical position of the spikelet receptacle relative to the proximal glume in species in this group.