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.

Arberella grayumii

HABIT Perennial; caespitose. Culms erect, or geniculately ascending; 35–50 cm long; 4–5 -noded. Culm-internodes terete; hollow; glandular (spot near node). Culm-nodes black; glabrous. Lateral branches lacking. Leaves cauline; 5–8 per branch; distichous. Leaf-sheaths hirsute. Ligule a ciliolate membrane; 0.2–0.4 mm long. Leaf-blade base asymmetrical; with a brief petiole-like connection to sheath; petiole 0.1–0.15 cm long; petiole pilose. Leaf-blades elliptic, or oblong; 5–10 cm long; 16–30 mm wide. Leaf-blade surface pilose; sparsely hairy, or moderately hairy; hairy abaxially, or on both sides. Leaf-blade apex acuminate.

INFLORESCENCE Monoecious; with male and female spikelets in the same inflorescence (or some all male). Inflorescence a panicle; comprising 1 fertile spikelets (and 8–16 male); terminal and axillary; with 1–5 peduncles per sheath. Axillary inflorescences present in upper axils.

Panicle open; linear; 1.5–4 cm long; bearing few spikelets.

Sexes segregated; on unisexual branches; with male below. Spikelets solitary. Fertile spikelets pedicelled. Male spikelets pedicelled; 2 in a cluster. Pedicels linear (male), or clavate (female).

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate; dorsally compressed; 13.5–15 mm long; 2.5 mm wide; breaking up at maturity; disarticulating below each fertile floret. Floret callus evident; 1 mm long; glabrous; truncate.

GLUMES Glumes deciduous; similar; with lower wider than upper; exceeding apex of florets; thinner than fertile lemma. Lower glume lanceolate; 13.5–15 mm long; 1 length of upper glume; membranous; pallid; without keels; 7 -veined. Lower glume lateral veins with cross-veins. Lower glume apex attenuate. Upper glume lanceolate; 13.5–15 mm long; 1.6 length of adjacent fertile lemma; membranous; pallid; without keels; 7 -veined. Upper glume lateral veins with cross-veins. Upper glume apex attenuate.

FLORETS Fertile florets female. Fertile lemma elliptic, or oblong; dorsally compressed; 8.7 mm long; 2.3 mm wide; indurate; pallid; shiny; without keel. Lemma surface with distinct germination flap; pubescent; hairy below. Lemma margins ciliate. Lemma apex acute. Palea 1 length of lemma; indurate; 4 -veined.

FLOWER Lodicules 3; 1 mm long; membranous; veined. Anthers 3; 1.2–1.6 mm long. Stigmas 2.

MALE Male spikelets distinct from female; 1 flowered; linear, or lanceolate; 3.8–5.2 mm long; glabrous. Male spikelet glumes absent. Male spikelet lemma 3 -veined; awned; with 0.1–0.5 mm long awn.

DISTRIBUTION South America: Mesoamericana.

NOTES Olyreae. Davidse 1994.

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