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Descriptions

W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson

© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.

Pentarrhaphis annua

HABIT Annual; caespitose. Culms erect; 10–25 cm long. Ligule a fringe of hairs; 0.3 mm long. Leaf-blades involute; 1–4 cm long; 1 mm wide.

INFLORESCENCE Inflorescence composed of racemes; terminal and axillary. Axillary inflorescences different from terminal (of 1–2 spikelets).

Racemes 2–10; borne along a central axis; cuneate; 0.8–0.9 cm long; bearing few fertile spikelets; bearing 1 fertile spikelets on each. Central inflorescence axis 2–3 cm long; flattened (crescentic); tip filiform (0.5–1mm, forked). Rhachis deciduous from axis; terminating in a barren extension; extension a forked bristle.

Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets sessile; 1 in the cluster.

STERILE SPIKELETS Companion sterile spikelets represented by awns; comprising 2 awns (hirsute); 2.5 mm long.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; with diminished florets at the apex. Spikelets cuneate; dorsally compressed; 3–3.5 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus bearded.

GLUMES Glumes dissimilar. Lower glume subulate; 2–2.5 mm long. Lower glume surface hispid. Upper glume subulate; 3.5–4 mm long. Upper glume surface scabrous.

FLORETS Fertile lemma elliptic; 3–3.5 mm long; cartilaginous; without keel; 3 -veined. Lemma lateral veins close to midvein. Lemma surface pilose; hairy in the middle. Lemma apex lobed; 3 -fid; with outer lobes shorter and with central lobe bidentate; incised 0.33 of lemma length; awned; 3 -awned. Principal lemma awn from a sinus; 4–5 mm long overall. Lateral lemma awns arising on margin of lemma; 4–5 mm long; subequal to principal. Palea 1 length of lemma. Palea apex dentate; 2 -fid. Apical sterile florets 1 in number; barren; lanceolate; 2.5–3 mm long. Apical sterile lemmas awned; 3 -awned.

FLOWER Anthers 3; 0.7–0.8 mm long.

FRUIT Caryopsis with adherent pericarp; ellipsoid; 1.3 mm long.

DISTRIBUTION South America: Mesoamericana.

NOTES Cynodonteae. Pohl.

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