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 humbertii

HABIT Perennial; caespitose. Rhizomes short. Culms decumbent; 90–100 cm long. Lateral branches sparse. Leaves basal and cauline. Leaf-sheaths outer margin hairy. Ligule a fringe of hairs. Leaf-blades 10–13 cm long; 4–5 mm wide; coriaceous; stiff. Leaf-blade margins scabrous; tuberculate-ciliate. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence a panicle.

Panicle contracted; elliptic; 5–15 cm long. Primary panicle branches simple; 2–5 cm long. Panicle branches scabrous.

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; 12–13 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus elongated; 1 mm long; bearded; pungent.

GLUMES Glumes persistent; dissimilar; exceeding apex of florets. Lower glume lanceolate; 12–13 mm long; 1 length of spikelet; chartaceous; dark brown; without keels; 3 -veined. Lower glume surface setose; hairy on veins; with tubercle-based hairs. Lower glume apex acuminate. Upper glume lanceolate; 1 length of spikelet; chartaceous; without keels; 3 -veined. Upper glume surface glabrous. Upper glume apex acute.

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. Fertile lemma oblong; 8 mm long; coriaceous; without keel. Lemma surface pilose; with a transverse row of hair tufts; bearing 9 hair tufts in all. Lemma margins involute; interlocking with palea keels. Lemma apex lobed; 2 -fid; with lanceolate lobes; awned; 3 -awned. Principal lemma awn from a sinus; geniculate; subterete below; 10 mm long overall; with twisted column; deciduous; abscissing from top of lemma. Lateral lemma awns arising on apex of lobes; 3–4 mm long. Palea 2 -veined. Palea keels approximate; thickened; winged; narrowly winged. Palea surface pubescent.

FLOWER Anthers 3.

FRUIT Caryopsis with adherent pericarp.

DISTRIBUTION Africa: western Indian ocean.

NOTES Arundinelleae. Camus 1992.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.