GrassBase - The Online World Grass Flora


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

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

Atractantha amazonica

HABIT Perennial; caespitose; clumped densely. Rhizomes short; pachymorph. Culms scandent; pendulous at the tip; 600 cm long; 40–80 mm diam.; woody. Culm-internodes terete; with small lumen; smooth; distally glabrous. Lateral branches dendroid. Bud complement 1. Branch complement many; thinner than stem. Culm-sheaths deciduous but leaving a persistent girdle; 7–9 cm long; 4 times as long as wide; glabrous; glabrous on shoulders. Culm-sheath ligule 0.2–0.3 mm high. Culm-sheath blade triangular; as wide as sheath at base; demarcated but persistent; erect; 3–5 cm long; 14–16 mm wide; acute. Leaves 5–9 per branch. Leaf-sheaths keeled (above); glabrous on surface; outer margin hairy. Leaf-sheath oral hairs ciliate; 3–6 mm long; dark (brown). Ligule an eciliate membrane; 0.5 mm long. Leaf-blade base with a brief petiole-like connection to sheath; petiole 0.2–0.3 cm long; petiole glabrous. Leaf-blades lanceolate; 10–17 cm long; 10–14 mm wide. Leaf-blade venation without cross veins. Leaf-blade surface glabrous. Leaf-blade margins scabrous. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence composed of racemes; terminal. Peduncle 5–13 cm long.

Racemes 1; single; 7–15 cm long; bearing 8–13 fertile spikelets on each. Rhachis glabrous on surface.

Spikelets appressed, or ascending. Fertile spikelets sessile.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension, or with a barren rhachilla extension, or with diminished florets at the apex. Spikelets linear, or lanceolate; subterete; 20–28 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes elongated between glumes and elongated below proximal fertile floret. Rhachilla elongation 1 mm long (between glumes), or 2–3.5 mm long (below floret).

GLUMES Glumes shorter than spikelet; thinner than fertile lemma. Lower glume elliptic; 4.5–5.5 mm long; membranous; without keels; keel-less throughout; 5 -veined. Lower glume apex awned; 1 -awned. Lower glume awn 1.5–3.5 mm long. Upper glume lanceolate; 6–7 mm long; membranous; without keels; keel-less except near apex; 7 -veined. Upper glume mucronate, or awned; 1 -awned. Upper glume awn 1–3 mm long.

FLORETS Fertile lemma lanceolate; subterete; 18–23 mm long; 1.2–2 mm wide; coriaceous; without keel; 7–11 -veined. Lemma margins convolute; covering most of palea; ciliolate. Lemma apex acuminate; pungent, or awned; 1 -awned. Principal lemma awn 1–3 mm long overall. Palea tightly convolute around flower; coriaceous; 4 -veined. Palea keels approximate; ciliolate. Rhachilla extension 10–20 mm long. Apical sterile florets 1 in number; lanceolate; 1–1.5 mm long.

FLOWER Lodicules absent. Anthers 3; 4–10 mm long. Stigmas 2. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp.

DISTRIBUTION South America: northern South America and Brazil.

NOTES Bambuseae. Judziewicz 2000.

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