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GrassBase - The Online World Grass Flora
Descriptions
W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson
© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.
Tristachya betsileensis
HABIT Perennial; caespitose. Rhizomes elongated. Culms erect, or geniculately ascending; 50–60 cm long; 5–6 -noded. Lateral branches lacking. Leaf-sheaths pilose. Ligule a fringe of hairs. Leaf-blades filiform; convolute; 10–15 cm long; 3–7 mm wide; stiff. Leaf-blade surface glabrous. Leaf-blade apex acuminate.
INFLORESCENCE Inflorescence a panicle. Peduncle 9 cm long.
Panicle open; oblong; 4–5 cm long; bearing few spikelets (3–6 triads). Primary panicle branches simple. Panicle branches capillary.
Spikelets in threes. Fertile spikelets pedicelled; 3 in the cluster. Pedicels fused to each other; united wholly; subequal.
FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; laterally compressed; compressed slightly; 13 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus elongated; 1 mm long; pilose; pungent. Floret callus hairs 0.8–1 mm long.
GLUMES Glumes persistent; dissimilar; exceeding apex of florets. Lower glume lanceolate; 9–10 mm long; 0.66 length of spikelet; chartaceous; dark brown; without keels; 3 -veined. Lower glume surface hispidulous; hairy generally. Lower glume hairs 4–5 mm long. Lower glume apex acuminate. Upper glume lanceolate; 1 length of spikelet; chartaceous; without keels; 3 -veined. Upper glume surface glabrous. Upper glume apex acuminate.
FLORETS Basal sterile florets male; with palea; separately deciduous. Lemma of lower sterile floret similar to upper glume; lanceolate; 1 length of spikelet; chartaceous; 5–7 -veined; acute, or acuminate. Fertile lemma oblong; 8 mm long; coriaceous; without keel. Lemma surface pubescent. Lemma margins involute; interlocking with palea keels. Lemma apex lobed; 2 -fid; with lanceolate lobes; with lobes 2 mm long; awned; 3 -awned. Principal lemma awn from a sinus; geniculate; subterete below; 12–13 mm long overall; with twisted column; deciduous; abscissing from top of lemma. Column of lemma awn 2.5–3 mm long. Lateral lemma awns arising on apex of lobes; 2–2.5 mm long. Palea 2 -veined. Palea keels approximate; thickened; winged; narrowly winged.
FLOWER Anthers 3. Ovary pubescent on apex.
FRUIT Caryopsis with adherent pericarp; hairy at apex.
DISTRIBUTION Africa: western Indian ocean.
NOTES Arundinelleae. Camus 1992.
Please cite this publication as detailed in How to Cite Version: 3rd February 2016.
