Cyperus colymbetes Kotschy & Peyr.

J. Browning, K.D. Gordon-Gray†, M. Lock, H. Beentje, K. Vollesen, K. Bauters, C. Archer, I. Larridon, M. Xanthos, P. Vorster, J. Bruhl, K. Wilson and X. Zhang (2020). Flora Zambesiaca Volume: 14: Cyperaceae. M.Á. García, J.R. Timberlake (Eds). Kew Publish

Type

Sudan, Tinné s.n. (W holotype). Anosporum colymbetes (Kotschy & Peyr.) Boeckeler in Bot. Zeitung (Berlin) 27: 26 (1869).

Morphology General Habit

Perennial, fairly robust, up to 54 cm tall, with an erect or creepy subwoody rhizome from which new culms develop at irregular intervals, often floating; culms green, 20–70 cm long, 3–5 mm wide, triquetrous to winged, smooth

Morphology Leaves

Leaves up to 20 long; leaf sheath reddish-brown to purple, very wide, ending in a thin ligule and a thick triangular apex, basal sheaths short, c. 1 cm, longer sheaths up to 20 cm long; leaf blade absent

Morphology Reproductive morphology Inflorescences Bracts

Involucral bract leaf- to bract-like, sometimes culm-like, erect, 8–12 mm long

Morphology Reproductive morphology Inflorescences

Inflorescence capitate; spikelets 3–15(20) per head, ovoid, 6–15 mm long, 4–10 mm wide, rachilla straight; glumes pale greenish or whitish, sometimes drying reddish-brown, ovate, 4.2–6 mm long, 2.4–3.7 mm wide, with large surface cells, 3–9-veined, keel thicker, scabrid towards apex, apex acute

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 3; filaments 3–5.4 mm long; anthers 0.9–1.6 mm long

Morphology Reproductive morphology Fruits

Nutlet brown, surrounded by yellow sterile tissue, 4.2–5.5 mm long, 1–1.4 mm wide, nutlet ellipsoid-oblong, 1.7–2.4 mm long, 0.9–1.1 mm wide, minutely papillose.

Distribution

Mozambique. Also in Sudan, Somalia, Uganda, Kenya and Tanzania.

Ecology

No habitat data from the Flora area; elsewhere it grows in boggy pools and in floating vegetation mats. In the Flora 0–50 m; elsewhere in Africa to 1100m.

Conservation

Least Concern; fairly widespread in Tropical Africa.

Recognition

This species is very close to Cyperus pectinatus. Both species have nutlets surrounded by corky tissue which makes them long-floating. C. colymbetes has much fewer and thicker culms which are almost winged. It also has larger involucral bracts, more spikes in the head, and the living spikes are whitish rather than brownish as in C. pectinatus.

Cyperaceae, K Hoenselaar, B. Verdcourt & H. Beentje. Hypolytrum, D Simpson. Fuirena, M Muasya. Flora of Tropical East Africa. 2010

Type

Type: Sudan, Tinne s.n. (W, holo.)

Morphology General Habit

Perennial, fairly robust, up to 54 cm tall, with an erect or creeping subwoody rhizome from which new culms develop at irregular intervals, often floating.

Morphology Culms

Culms green, 20–70 cm long, 3–5 mm wide, triquetrous to winged, smooth

Morphology Leaves

Leaf blade absent Leaves with leaf sheath reddish-brown to purple, very wide, ending in a thin ligule and a thick triangular apex, short basal sheaths as short as 1 cm, longer sheaths up to 20 cm long.

Morphology Reproductive morphology Inflorescences Bracts

Involucral bract leaf- to bract-like, sometimes culm-like, erect, 8–12 mm long

Morphology Reproductive morphology Inflorescences

Inflorescence capitate.

Morphology Reproductive morphology Inflorescences Spikelets

Spikelets 3–15(–20) per head, ovoid, 6–15 mm long, 4–10 mm wide, rachilla straight.

Morphology Reproductive morphology Inflorescences Bracts Glume

Glumes reddish-brown, ovate, 4.2–6 mm long, 2.4–3.7 mm wide, with large surface cells, 3–9-veined, keel thicker, scabrid towards apex, apex acute

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 3.

Morphology Reproductive morphology Flowers Androecium Stamens Filaments

Filaments 3–5.4 mm long.

Morphology Reproductive morphology Flowers Androecium Stamens Anthers

Anthers 0.9–1.6 mm long

Morphology Reproductive morphology Fruits

Nutlet brown, surrounded by yellow sterile tissue, 4.2–5.5 mm long, 1–1.4 mm wide, nutlet ellipsoid-oblong, 1.7–2.4 mm long, 0.9–1.1 mm wide, minutely papillose.

Ecology

Muddy areas, on swampy ground, in (dried-up) pools and in shallow water; 10–950 m

Conservation

Least Concern due to its wide distribution

Note

This species is very closely related to C. pectinatus Vahl. Both species have nutlets surrounded by corky tissue to make it long-floating. C. colymbetes has much thicker and fewer culms which are almost winged. It also has larger involucral bracts.

Distribution

Range: Sudan, Somalia, Mozambique Flora districts: U2 K5 K7 T3 T4 T6

M. Thulin et al. Flora of Somalia, Vol. 1-4 [updated 2008] https://plants.jstor.org/collection/FLOS

Morphology General Habit

Fairly robust perennial with an erect or creeping subwoody rhizome, from which new stems develop at irregular intervals

Morphology Stem

Stems 30–70 cm long and 3–5 mm thick, sharply triangular to winged, green, glabrous

Morphology Leaves

Leaf-blades absent; sheaths very wide, reddish brown to purple, ending in a thin ligule and a thick triangular apex

Morphology Reproductive morphology Inflorescences

Inflorescence a congested pale and almost whitish anthela with sessile spikelets only; solitary involucral bract leafy to stem-like, 8–12 mm long and continuing in the direction of the stem; anthela 1–2.5 cm in diam., consisting of 6–15 crowded spikelets

Morphology Reproductive morphology Inflorescences Spikelets

Spikelets 8–12 x 5–7 mm, ovate, light green to pale reddish brown, 12–30-flowered

Morphology Reproductive morphology Inflorescences Bracts Glume

Glumes 4.5–5.5 mm long, ovate, reddish brown with large surface-cells, 3–9-nerved (but nerves often indistinct); midrib thicker and often scabrid at apex, not excurrent

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 3

Morphology Reproductive morphology Flowers Gynoecium Style

Style 3-branched, or rarely 2-branched

Morphology Reproductive morphology Fruits

Nutlet 4–5 x 1.2–1.4 mm including a 1–2 mm long narrow beak and a 0.8–1.2 mm long basal tissue; the nutlet brown, surrounding sterile tissue yellow.

Distribution

S2 scattered in tropical Africa and Madagascar.

Ecology

Altitude below 100 m.