Schoenus cuspidatus, Rottb.

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 : 520-521

4. Key to the species in the Schoenus cuspidatus group (part I)

1a. Proximal primary inflorescence bract conspicuously expanded at base; longitudinal veins at base of bract often prominent: 2a. Culms usually thick (0.7–1.1 mm wide) and appearing semi-succulent; plants widespread throughout South Africa (usually found within 200 km of the S. and E. coasts): …………………………………………………………… 1. Schoenus auritus 2b. Culms thin (0.4–0.6 mm) and not appearing semi-succulent; plants restricted to granitic sites on the Cape Peninsula: …………………………………………………… 2. Schoenus graminifolius 1b. Proximal primary inflorescence bract not conspicuously expanded at base; longitudinal veins at base of bract not prominent: 3a. Spikelets linear-lanceolate ( Fig. 1 ); nutlets narrow-ellipsoidal ( Fig. 2C, D ): 4a. Plants usually> 350 mm in height; spikelets 4.5–7.5 mm in length, often reduced sexually with only male or female organs present:……………………………………………… 3. Schoenus ligulatus 4b. Plants <340 mm in height; spikelets mostly <4 mm in length, bisexual spikelets always present:……………………… 4. Schoenus exilis 3b. Spikelets lanceolate or ovate ( Fig. 1 ); nutlets broad-ellipsoidal ( Fig. 2 ): 5a. Spikelets lanceolate:

6a. Glume margins with reddish-purple streaks adjacent to the hyaline margins ( Fig. 3E, F ): 7a: Older leaves usually curled; membranaceous sheaths with reddish-purple streaks:……………………………… 5. Schoenus bolusii 7b. Older leaves usually straight; sheaths firm (i.e. not membranaceous) and solid red to brown in colour: ……………………………………………..…… 6. Schoenus submarginalis

6b. Glume margins without reddish-purple streaks adjacent to the hyaline margins: 8a. Basal leaves reduced in length (usually a third to a quarter of culm length, never over half of culm length); glumes usually dark-reddish brown in colour; plants of mountainous regions of the Western and Eastern Cape Provinces:……….…….…….......……… 7. Schoenus crassiculmis 8b. Basal leaves well-developed in length (often over half of culm length); glumes medium brown to light reddish-brown in colour; plants endemic to the Eastern Cape and KwaZulu-Natal or Agulhas Plains region of South Africa): 9a. Spikelets <4.0 mm in length; glumes often thin and membranaceous ( Fig. 4N ); plants endemic to quartz patches on shale-derived soils in the Overberg region of the Western Cape Province of South Africa:…..…...……………………....….... 8. Schoenus quartziticus 9b. Spikelets usually>4.0 mm in length; glumes firm ( Fig. 4O ); plants endemic to grasslands and wetlands of the Eastern Cape and KwaZulu-Natal Provinces of South Africa):……...…. 9. Schoenus limosus 5b. Spikelets ovate ( Fig. 1 ): 10a. Sheaths loose; leaves appearing flat as they are usually not-channelled above ligule; plants endemic to mountainous regions of the southern Western Cape Province of South Africa: ……………………………………...….………... 10. Schoenus purpurascens 10b. Sheaths firm; leaves appearing terete as they are channelled above ligule; plants endemic to the Agulhas Plains region of South Africa: 11a. Spikelets with firm prophylls that often shine; prophyll mucros>3.0 mm; base of culms terete and with sheath not holding several leaf bases together:………………………………….…. 11. Schoenus prophyllus 11b. Spikelets with prophylls that are not firm and shining; prophyll mucros <2.4 mm long; base of culm flattened and with sheath holding several leaf bases together ( Fig. 5 ):……………….. 12. Schoenus calceolus

Figures

Fig. 1. Spikelet variation in the Schoenus cuspidatus and allies group found in southern Africa: A—S. cuspidatus (lanceolate spikelet), B—S. crassus (lanceolate spikelet), C—S. auritus (lanceolate spikelet), D—S. graminifolius (lanceolate spikelet), E—S. calceolus (ovate spikelet) and F—S. ligulatus (linear-lanceolate spikelet).The black scale bar next to the spikelets represents 1 mm.

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.3. Examples of plants from six species of the Schoenus cuspidatus and allies group found in southern Africa,showing the corresponding inflorescences andspikelets beneath each plant: A, G and M—S.auritus; B, H and N—S.graminifolius; C, I and O—S. ligulatus; D,J, and P—S.exilis; E,K and Q—S.bolusii; and F, L and R—S.submarginalis. 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.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. 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.