Schoenus quadrangularis Boeckeler

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 : 306

3. Schoenus quadrangularis Boeckeler , Linnaea 38: 274 — 275 (1874).

Epischoenus quadrangularis (Boeckeler) C.B.Clarke in T.A. Durand & H. Schinz, Consp. Fl. Afric. 5: 657 (1894). Tetraria quadrangularis (Boeckeler) Kuk ü., Repert. Spec. Nov. Regni Veg. 44: 191 (1938).

Type: South Africa, Western Cape Province, 3318 (Cape Town): Summit of Table mountain near Cape Town, (‒CD), 24 Jan 1811, Burchell 557 ( K [ K000244895 ], lecto.!, here designated) . [Note: Boeckeler (1874) cited only one specimen in his protologue of S. quadrangularis : “ Burchell. hb. no. 557”. Subsequently, Levyns (1959) reported that Burchell 557 from K was an isotype. The only specimen of this collection number we found during our search was the one at K, which was not Boeckeler’ s home herbarium. Therefore, we designate the specimen at K as a lectotype.].

Caespitose, perennial graminoid, aphyllopodic, culms 4-angled (i.e. quadrangular) ( Fig. 3C and 3H ). Culms deeply ridged and quadrangular, (370 —)491 — 648(‒1005) £ (0.5 —)0.8 — 1.0(‒1.7) mm. Leaves, blades absent. Sheaths dark red at base, longitudinally striate, open, central vein terminating in a mucro up to several mm long, chartaceous to firm. Ligule absent. In fl orescence a narrow, pseudolateral panicle, (11 —)21‒30(‒41) £ (1.5 —)3.0‒4.0(‒6.0) mm, proximal rachis length (3.0 —)10.0‒12.0(‒23.0) mm, 2 dominant primary inflorescence bracts appressed to central axis and spikes ( Figs. 3H and 7C ). Proximal primary in fl orescence bracts (24 —)40‒52(‒66) mm long, without lateral chartaceous extensions, flat to partially involute, narrow at base, firm, apex acute to obtuse, exceeding length of inflorescence slightly, sometimes slightly hairy. Spikes 1‒3 (usually 2), (5 —) 11‒16(‒22) mm long, aggregated into narrow clusters along rachis, only slightly overlapping. Spikelets linear-lanceolate to lanceolate, 1 — 3 (usually 2) spikelets per spike, (5.7 —)7.5‒9.1(‒12.0) £ (0.9 —) 1.1‒1.6(‒3.2) mm, pedicellate, colour ranging from light reddish-brown to dark brown, texture varying from chartaceous to firm and opaque, sometimes almost completely concealed by primary inflorescence bracts, varying number of sterile glumes at spikelet base ( Fig. 8C ). Proximal spikelet prophyll absent. Rachilla (0‒)1.9‒4.6(‒12.0) mm long. Glumes 3‒9 per spikelet, ranging in texture from chartaceous to opaque and firm, proximal glume varying in length, (2.3‒) 3.4‒5.3(‒7.7) mm long, subproximal glume (1.1‒)3.2‒5.8(‒8.2) mm long, upper glumes longer than basal ones, apex acute to obtuse. Glume mucros often absent, proximal mucro 0‒0.2(‒1.5) mm long, subproximal mucro 0‒0.5 mm long. Stamens 3 per floret, anthers 2.7 mm long (1 observed). Stigmas 3-branched, vestigial stigmas present. Perianth bristles absent (i.e. yet to be observed). Suprafloral axis sometimes thickening and strengthening, eventually curving. Nutlet 2.5‒3.1 £ 1.4 mm, broad elliptic, trigonous (ridges sometimes prominent), shiny, yellowish in colour when young and turning dark reddish black with maturity, stipitate, pedicel enlarged and staying yellow with maturity; nutlet beak short, 0.1‒0.2 mm ( Fig. 10C ). ( Figs. 3 , 7 , 8 and 10 )

Flowering: September to March

Distribution and ecology: Schoenus quadrangularis is endemic to the mountains of Southern South Africa, ranging from the Cape Peninsula in the west to the Groot Winterhook Mountains of the Eastern Cape Province ( Fig. 13 ). Collections of this species mostly come from damp sites in the mountains, with elevations ranging from 82‒ 1370 m.

Diagnosis: The deeply-ridged, quadrangular stems of S. quadrangularis are unique among the southern African Schoeneae species. These 4-angled stems are most evident directly below the inflorescences.

Additional collections examined

South Africa. EASTERN CAPE: 3324 (Steytlerville): Cockscomb Mountain, (‒DB), 16 Feb 2016, Euston-Brown 4591 ( BOL) . WESTERN CAPE: 3318 (Cape Town): one clump beside the path near Wynberg Reservoir , (‒ CD), May 1938, Esterhuysen 720 ( BOL, K, PRE) ; Table Mt. , E side, Carrel's Ledge , (‒CD), 20 Oct 1940, Esterhuysen 4899 ( BOL) ; Table Mountain , Echo Valley , (‒CD), 11 Sep 2004, Verboom 734 ( BOL) ; Table Mountain National Park , along trail between Skeleton Gorge and Maclear's Beacon, c. 400 m before beacon, (‒CD), 9 May 2018, Elliott & van Mazijk TE2016_356 ( BOL) ; Table Mountain National Park , along trail between Skeleton Gorge and Maclear's Beacon, c. 200 m from start of trail from end of Skeleton Gorge , (‒CD), 9 May 2018, Elliott & van Mazijk TE2016_360 ( BOL) ; Table Mt. , Blinkwater Ravine , (‒CD), without date, Marloth 4824 ( NBG) . 3320 (Montagu): S slopes of Swellendam Mt. , (‒CD), 4 Feb 1941, Esterhuysen 4797 ( BOL) ; Marloth Nature Reserve , towards western end of Langkuilen valley , (‒ CD), 22 Nov 1989, McDonald 1865 ( NBG, PRE) ; Swellendam Mt., Sample C , S slopes of 9 O'Clock Peak above Swellendam , (‒DC), 6 Nov 1962, Taylor 4237 ( PRE) ; kloof on S slopes of Langebergen , near Strawberry Hill , (‒DD), 10 Sep 1944, Esterhuysen 10,497A ( BOL) ; near stream on lower S slopes of Lemoenshoek Pk. , (‒DD), 27 Mar 1948, Esterhuysen 14,407 ( BOL) . 3321 (Ladismith): Langeberg, Riversdale , (‒CD), 15 Nov 1892, Schlechter 1765 ( K, NBG). 3418 (Simonstown): Table Mt. , lower plateau; foot of wall above Window Gorge , (‒AB), Nov 1935, Esterhuysen 379 ( BOL) ; Steenbras Dam , slopes E of dam in permanent monitoring site H8-3B, (‒BB), 21 Sep 2016, Euston-Brown 4738 ( BOL) ; Somerset Sneeuwkop , (‒BB), Feb 1943, Stokoe s.n. ( SAM) ; banks of stream in mountains near Palmiet River mouth, (‒BD), 21 Jan 1946, Esterhuysen 12,550 ( BOL) ; between fishing village & Palmiet River mouth, (‒BD), 1 Feb 1947, Levyns 8157 ( BOL, K) ; Platberg plot 23/42L, Kogelberg For. Res. , (‒BD), 23 Feb 1968, Boucher 49 ( NBG) ; Kogelberg Forest Reserve , end of Spinnekopneskloof road, (‒BD), 2 Apr 1970, Boucher 1212 ( NBG) ; Harold Porter Reserve , (‒BD), 23 Nov 1989, Esterhuysen 36,886 ( NBG) ; Kogelberg Nature Reserve , Lowsrivier, c. 500 m up Lowsrivier on steep S-facing slope on N side river, (‒ BD), 24 Oct 2016, Euston-Brown 5073 ( BOL) ; Palmiet River Mouth , (‒ BD), Feb 1949, Levyns 9376 ( BOL) ; Kogelberg , (‒BD), Nov 1944, Stokoe s.n. ( SAM) ; Table Mt. , plateau, Table Mt. , lower plateau, foot of wall above Window Gorge , (‒CD), Nov 1935, Esterhuysen 379 ( BOL). 3419 (Caledon) : Lebanon State Forest , Catchment II d., (‒AA), Apr 1967, Kruger 435 ( NBG) ; Lebanon Forest Reserve , Jakkalsrivier Catchment (Ig), (‒AA), 27 Feb 1969, Kruger 816 ( NBG) ; Hottentots Hollands Nature Reserve , c. 1.25 km from Nuweberg parking lot, along jeep track to Landdroskop Hut , (‒AA), 18 Feb 2017, Elliott & Muasya TE2016_172 ( BOL) ; Houw Hoek , (‒AA), 7 Feb 1896, Schlechter 7402 ( BOL, K, SAM) ; Klein River Mts. , (‒AD), 1 Sep 1940, Esterhuysen 2916 ( BOL, K) ; Vogelgat, Miracle Kloof , (‒AD), 21 Dec 1982, Williams 3401 ( NBG) ; Vogelgat, (‒AD), 11 Nov 2007, Muasya & Stirton 3181 ( BOL) ; Vogelgat Private Nature Reserve , Miracle Kloof , c. 10 m upstream of trail to Vogelpool, (‒AD), 24 Aug 2018, Elliott TE2016_367 ( BOL) ; marshy S slopes of Rivier Zonder Einde Mt. near Greytown, (‒BA), 30 Nov 1952, Esterhuysen 20,794 ( BOL) ; Riviersonderend Mountains , between Greyton and Perdkop, plots 61 — 67, (‒BA), 7 Feb 1979, Campbell 10,654 ( NBG) ; Cascades, Betty's Bay , (‒BD), 20 Sep 1950, Parker 4515 ( BOL, K, SAM) .

Figures

Fig. 3. Examples of plants from five species of the Epischoenus group found in southern Africa, showing the corresponding inflorescences beneath each plant: A and F—S. dregeanus; B and G—S.complanatus; C and H—S. quadrangularis; D and I—S.selinae; and E and J—S.rigidus. 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. 13. Documented locations of S.quadrangularis.