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.

Aira

HABIT Annual. Culms erect, or geniculately ascending (4); slender (3/3); 2–22.87–55 cm long. Ligule an eciliate membrane. Leaf-blades filiform (6), or linear (2).

INFLORESCENCE Inflorescence a panicle; subtended by an unspecialized leaf-sheath (7), or an inflated leaf-sheath (1); exserted (7), or embraced at base by subtending leaf (1).

Panicle open (7), or spiciform (1).

Spikelets solitary. Fertile spikelets pedicelled. Pedicels filiform (7), or linear (1); tip widened (1/4), or globular (1/4), or pyriform (2/4).

FERTILE SPIKELETS Spikelets comprising 2 fertile florets; without rhachilla extension. Spikelets oblong, or ovate (6); laterally compressed; 1.3–2.485–4.2 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus pubescent.

GLUMES Glumes persistent; reaching apex of florets (1), or exceeding apex of florets; thinner than fertile lemma; gaping. Lower glume ovate; 1 length of upper glume; membranous; 1-keeled; 1 -veined, or 2–3 -veined (6). Lower glume lateral veins absent (4), or obscure (2), or distinct (4). Lower glume surface without pits. Lower glume apex entire, or erose (1); obtuse (3), or acute (5); muticous (7), or mucronate (2). Upper glume ovate; 1–1.287–1.5 length of adjacent fertile lemma; membranous; 1-keeled; 1 -veined, or 2–3 -veined (6). Upper glume apex obtuse (3), or acute (5); muticous (7), or mucronate (2).

FLORETS Fertile lemma ovate; laterally compressed; lanceolate in profile (6/6); cartilaginous; without keel; wingless; 5 -veined. Lemma lateral veins obscure. Lemma surface scaberulous (6), or scabrous (2); unwrinkled; without grooves. Lemma margins involute; covering most of palea. Lemma apex dentate; 2 -fid (7), or 3 -fid (1); muticous (1), or awned; 1 -awned. Principal lemma awn dorsal; geniculate. Palea 0.7 length of lemma; membranous (2), or cartilaginous (6); 2 -veined (6/6).

FLOWER Lodicules 2; membranous. Anthers 3. Stigmas 2.

FRUIT Caryopsis with adherent pericarp (6/6); fusiform (4/4); isodiametric (4/4); biconvex (4/4); smooth (4/4); apex unappendaged (6/6). Embryo 0.2 length of caryopsis. Hilum punctiform (6/6).

DISTRIBUTION Europe, or Africa (5), or Temperate Asia (3), or Tropical Asia (1), or Australasia (5), or Pacific (1), or North America (3), or South America (3), or Antarctica (2).

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