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.

Piresia

HABIT Perennial. Culms erect (1/1), or geniculately ascending (1/1); 6.6–23.36–50 cm long; wiry. Ligule an eciliate membrane. Leaf-blade base with a brief petiole-like connection to sheath. Leaf-blades linear (1), or lanceolate (3), or oblong (1), or ovate (1); herbaceous (4), or chartaceous (1).

INFLORESCENCE Monoecious; with male and female spikelets in the same inflorescence. Synflorescence on the same culm as leaves (2), or on a separate leafless culm. Inflorescence composed of racemes; terminal (3), or terminal and axillary (2).

Racemes single; bearing few fertile spikelets; bearing 2 fertile spikelets on each (3), or 3–5 fertile spikelets on each (2), or 6 fertile spikelets on each (1).

Sexes mixed. Spikelets solitary (2), or in pairs. Fertile spikelets pedicelled; 1 in the cluster. Male spikelets sessile (4), or pedicelled (1); 1 in a cluster. Pedicels cuneate.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate (1), or elliptic (3), or ovate (2); dorsally compressed; 4.98–6.358–8 mm long; breaking up at maturity; disarticulating below each fertile floret.

GLUMES Glumes deciduous; reaching apex of florets (3), or exceeding apex of florets (2); thinner than fertile lemma. Lower glume elliptic (3), or ovate (2); 1–1.02–1.1 length of upper glume; herbaceous; without keels; 5 -veined (4), or 8 -veined (1). Lower glume lateral veins without ribs (3), or ribbed (2). Lower glume surface without pits; glabrous (4), or puberulous (1). Lower glume apex acute (2), or acuminate (3); muticous (4), or awned (1). Upper glume elliptic (3), or ovate (2); 0.9–1.02–1.2 length of adjacent fertile lemma; herbaceous; without keels; 3 -veined (3/4), or 5 -veined (1/4). Upper glume lateral veins without ribs (3), or ribbed (2); with cross-veins (2/2). Upper glume surface glabrous (4), or puberulous (1). Upper glume apex acute (2), or acuminate (3).

FLORETS Fertile florets female. Fertile lemma lanceolate (1), or elliptic (3), or ovate (2); indurate; without keel; wingless; 5 -veined (4/4). Lemma surface unwrinkled; without grooves; pubescent. Lemma margins exposing palea (4), or covering most of palea (1). Lemma apex truncate (1/1). Palea membranous (1), or indurate (4); 2 -veined (4/4).

FLOWER Lodicules 3 (1/1). Anthers 3. Stigmas 1 (1/1).

FRUIT Caryopsis with adherent pericarp (2/2); ellipsoid (1/2), or ovoid (1/2). Embryo 0.2 length of caryopsis. Hilum linear (2/2); 0.75–0.875–1 length of caryopsis.

MALE Male spikelets distinct from female; lanceolate. Male spikelet glumes absent. Male spikelet lemma muticous.

DISTRIBUTION South America.

Please cite this publication as detailed in How to Cite Version: 27th January 2014.