Schoenus dregeanus (Boeckeler) Kuntze

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 : 299-303

1. Schoenus dregeanus (Boeckeler) Kuntze , Revis. Gen. Pl. 2: 756 (1891).

Elynanthus dregeanus Boeckeler , Linnaea 38: 262 — 263 (1874). Tetraria dregeana (Boeckeler) C.B.Clarke in T.A. Durand & H. Schinz, Consp. Fl. Afric. 5: 661 (1894). Epischoenus dregeanus (Boeckeler) Levyns , J. S. African Bot. 25: 76 (1959).

Type: South Africa, Western Cape Province, 3319 (Worcester): Du Toit’ s Kloof , (‒CA), without date, Drege 1632d ( B [ B 100166741 ], lecto. — image! . [Note: Levyns (1959) listed Drege 1632a as the ‘lectotype’ of this name, which is the same specimen that Clarke (1900) had cited under his description of T. dregeana . We assume this to be the same specimen as Drege 1632d.].

[Note: In the protologue of Elynanthus dregeanus, Boeckeler (1874) cites only one specimen — ‘ Drege’— without giving a collection locality or date. When Clarke (1900) described T. dregeana , he noted that Drege’ s 1632a was collected from ‘Dutoits Kloof’ and that he had seen the specimen. T.L. Elliott searched through Drege’ s collection locality notes (see Drege, 1843) and was not able to find information for this collection number. However, we think that Clarke might have had access to additional information that we have yet to locate.].

Caespitose, perennial graminoid, phyllopodic, spikelets linear ( Figs. 3A, 3F and 8 ). Culms terete with shallow ridges, (215 —) 352 — 438(‒474) £ 0.5‒0.8(‒1.0) mm. Leaves basal, ranging from rudimentary to fully developed, less than half of culm height, 1 — 5, (5 —) 9 — 71(‒161) £ 0.2 — 0.5(‒0.7) mm, developing from sheaths along culm, usually proximally channelled, straight, margin usually serrate above sheath. Sheaths reddish-brown to dark reddish-black, longitudinally striate, closed except distal portion, semi-firm to firm. Ligule 0.2 — 0.4(‒1.0) mm. In fl orescence a pseudolateral panicle, (17 —)24‒31 (‒52) £ 3.0‒5.0(‒7.5) mm, proximal rachis length (2.5 —)9.0‒12.8(‒ 28.0) mm ( Figs. 3F and 7A ). Proximal primary in fl orescence bracts (5 —) 35‒50(‒81) mm long, narrow, without lateral chartaceous extensions, involute, apex acute but breaking-off readily, exceeding length of inflorescence. Spikes 2‒4, (8 —)11‒17(‒25) mm long, aggregated into long, narrow clusters along rachis, overlapping. Spikelets linear, 1 — 3 spikelets per spike, (6.1 —)7.2‒9.3(‒11.0) £ (0.7 —)1.1‒1.6(‒2.2) mm, pedicellate (pedicels varying in length), colour ranging from light to dark brown/black, texture ranging from chartaceous to firm and opaque, not concealed by primary inflorescence bracts, varying number of sterile glumes at spikelet base. Proximal spikelet prophyll not fully developed or absent. Rachilla (0.2‒)2.0‒4.0(‒8.6) mm long. Glumes 3‒8 per spikelet, texture chartaceous to opaque and firm, hyaline margins sometimes present (more evident on darker coloured spikelets), lower glumes often relatively long, proximal glume (1.6‒)3.1‒5.2(‒7.1) mm long, subproximal glume (1.8‒)3.2‒5.2(‒8.5) mm long, upper glumes longer than basal ones, apex acuminate to obtuse. Glume mucros often absent, proximal mucro 0‒0.9(‒1.4) mm long, subproximal mucro 0‒1.2(‒2.3) mm long. Stamens 3 or 6 (usually 3) per floret, anthers 1.9 mm long (1 observed). Stigmas 3- branched, vestigial stigmas present. Perianth bristles sometimes present (see Browning and Gordon-Gray, 1995). Suprafloral axis sometimes thickening and strengthening, eventually curving. Nutlet 1.6‒1.8(‒2.3) £ 0.9‒1.0(‒1.2) mm, obovoid or oblong, trigonous, rough (especially near the base and apex), stipitate, yellowish in colour when young and turning reddish-brown at the apex and base with maturity; nutlet beak short and narrow, 0.1‒0.2 mm ( Fig. 10A ). ( Figs. 3 , 7 , 8 and 10 )

Flowering: December to April

Distribution and ecology: Schoenus dregeanus is a narrowly-distributed species, with most specimens having been collected from the Cederberg and Worcester areas of South Africa ( Fig. 11 ). However, one specimen has been collected from the Riviersonderend Mountains and another from the Prince Albert region. Schoenus dregeanus tends to occur in moist, mountainous habitats ranging from about 600 — 1400 m in elevation. Although its distribution is relatively limited, population sizes of S. dregeanus can be high so that this species sometimes dominates certain moist habitats.

Diagnosis: The last internode of the spikelets of S. dregeanus is elongated, which is a character common throughout all species of the Epischoenus group. However, the presence of leaves along the lower part of its culms differentiates S. dregeanus from the other members of the Epischoenus group, although this character is shared with most species in both the S. compar — S. pictus and S. cuspidatus groups. Schoenus dregeanus has distinctive nutlets that are rough at the base and apex ( Fig. 10A ), whereas other species in the Epischoenus group have either entirely matted or shiny nutlets.

The linear spikelets of S. dregeanus are most similar in shape to those of Schoenus ligulatus (Boeckeler) Kuntze (see Elliott et al., 2019; Fig. 3O); however, the spikelets of S. dregeanus lack prophylls at their base. The distribution of S. dregeanus and S. gracillimus overlap and sometimes the two species resemble each other; however, the spikelets of S. gracillimus are often pendulous in this region.

Additional collections examined

South Africa. WESTERN CAPE: 3219 (Wuppertal): Cederbergen, shale band below Tafelberg, (‒AC), 26 Feb 1947, Esterhuysen 13,798 (BOL); E foot of Schurweberg, Cold Bokkeveld, (‒CD), 19 Apr 1946, Esterhuysen 12,668 (BM, BOL, NBG). 3319 (Worcester): Groot Winterhoek Wilderness Area, on edge of trail near Disa Pool, c. 1 km from parking lot, (‒AA), 20 Oct 2018, Elliott TE2016_410 (BOL); 28 Sep 2019, Elliott TE2016_435 (BOL); Elands Kloof, (‒AC), 13 Dec 1946, Levyns 8096 (BOL); 14 Dec 1946, Levyns 8111 (BOL); 3 Oct 1948, Levyns 9226 (BOL [2 sheets]); 17 Dec 1948, Levyns 9322 (BOL), Levyns 9326 (BOL), Levyns 9329 (BOL), Levyns 9338 (BOL); 19 Dec 1948, Levyns 9367 (BOL); 16 Apr 1949, Levyns 9379 (BOL [2 sheets]); 17 Apr 1949, Levyns 9386 (BOL); 5 Apr 1952, Levyns 9838 (BOL); without date, Levyns 9326 (K); Waaihoek Mt., (‒AD), 16 Dec 1942, Esterhuysen 8341 (BOL, PRE); on W slopes of Michell Peak, (‒AD), 10 Dec 1948, Esterhuysen 15,146 (BOL); SW slopes of Michell Pk., (‒AD), 27 Mar 1949, Esterhuysen 15,213 (BOL, NBG); Mt. Superior, Waaihoek Mts., (‒AD), 24 Dec 1950, Esterhuysen 18,199 (BOL, K); N slope on way to Milner Peak, (‒AD), 9 Sep 2018, Elliott TE2016_383 (BOL); ‘In Montibus Pone Mitchels-Pass’, (‒AD), 15 Jan 1896, Schlechter 9964 (BM, BOL, GRA, K, PRE); Suurvlakte, behind Seven Sisters, (‒CA), 31 Mar 1945, Esterhuysen 11,544 (BOL); Bains Kloof, swamp on ridge near Bot. Stn., (‒CA), 7 Apr 1956, Esterhuysen 25,608 (BOL); Limietberg Nature Reserve, Happy Valley trail, 50 m from start of trail in Eerste Tol, (‒CA), 27 Apr 2017, Elliott, Muasya & Betz TE2016_190 (BOL); Limietberg Nature Reserve; growing on SE-facing slope of R301, c. 2 km to NE of Bainskloof community, (‒CA), 25 Jun 2017, Elliott & Muasya TE2016_204 (BOL); Limietberg Nature Reserve, near beginning Happy Valley trail adjacent to Bainskloof community, (‒CA), 25 Jun 2017, Elliott & Muasya TE2016_213 (BOL); Limietberg Nature Reserve, along Bobbejaansrivier hiking trail, c. 2.5 km before waterfall, (‒CA), 1 May 2018, Elliott, Muasya & van Mazijk TE2016_347 (BOL). 3321 (Ladismith): Seven Weeks Poort, (‒AD), without date, Stokoe 7184 (BOL). 3419 (Caledon): Riviersonderend Mountain Catchment Area, c. 1.5 to 1.75 km to NNW of reception towers, (‒BA), 24 Oct 2018, Elliott TE2016_421 (BOL).

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. 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. 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. 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. 11. Documented locations of S.dregeanus.