Avena L.

Gramineae, W. D. Clayton, S. M. Phillips And S. A. Renvoize. Flora of Tropical East Africa. 1974

Morphology General Habit

Annuals

Morphology Leaves

Leaf-blades flat

Morphology Reproductive morphology Inflorescences

Inflorescence an open, or rarely contracted, panicle with large pendulous spikelets

Morphology Reproductive morphology Inflorescences Spikelets

Spikelets 2–6-flowered (rarely more), the lower 1–3 florets hermaphrodite, the others ± reduced, the terminal floret barren or vestigial; rhachilla disarticulating above the glumes and sometimes between the florets, or not at all in cultivated races; glumes lanceolate to ovate or elliptic, equal or almost so, rounded on the back, scarious-membranous or herbaceous-membranous, with thin margins, 7–11-nerved; lemmas lanceolate to ovate or oblong, shorter than or equalling the glumes, rarely exserted, rounded on the back, herbaceous, becoming hardened, 5–9-nerved, with a geniculate (or rarely straight) awn from the back, or awnless in some cultivated races; paleas shorter than the lemmas, 2-keeled; stamens 3; stigmas 2.

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Morphology General Habit

Annual. Culms erect (18), or geniculately ascending (13), or decumbent (2), or prostrate (1); 7-71.73-180 cm long. Lateral branches lacking (13/13). Ligule an eciliate membrane.

Morphology Reproductive morphology Inflorescences

Inflorescence a panicle. Panicle open (20), or contracted (1). Spikelets pendulous (19/19); solitary. Fertile spikelets pedicelled. Pedicels filiform.

Morphology Reproductive morphology Inflorescences Spikelets

Spikelets comprising 1 fertile florets (1), or 2 fertile florets (17), or 3 fertile florets (19), or 4 fertile florets (9), or 5 fertile florets (4), or 6 fertile florets (1); with a barren rhachilla extension. Spikelets lanceolate (13), or cuneate (8); laterally compressed; 11-24.4-50 mm long; persistent on plant (6), or breaking up at maturity (15); disarticulating below each fertile floret (7/15), or above glumes but not between florets (8/15). Rhachilla internodes glabrous (17), or pilose (4). Floret callus brief (6), or evident (12), or elongated (3); glabrous (5/18), or pubescent (1/18), or bearded (12/18); obtuse (19), or acute (1), or pungent (1).

Fertile

Spikelets comprising 1 fertile florets (1), or 2 fertile florets (17), or 3 fertile florets (19), or 4 fertile florets (9), or 5 fertile florets (4), or 6 fertile florets (1); with a barren rhachilla extension. Spikelets lanceolate (13), or cuneate (8); laterally compressed; 11-24.4-50 mm long; persistent on plant (6), or breaking up at maturity (15); disarticulating below each fertile floret (7/15), or above glumes but not between florets (8/15). Rhachilla internodes glabrous (17), or pilose (4). Floret callus brief (6), or evident (12), or elongated (3); glabrous (5/18), or pubescent (1/18), or bearded (12/18); obtuse (19), or acute (1), or pungent (1).

Morphology Reproductive morphology Inflorescences Bracts Glume

Glumes persistent (15/15); shorter than spikelet (2), or reaching apex of florets (1), or exceeding apex of florets (18); thinner than fertile lemma (20), or similar to fertile lemma in texture (1); parallel to lemmas (2), or gaping (19). Lower glume lanceolate; 0.5-0.9517-1 length of upper glume; membranous; without keels; 3-4 -veined (2), or 5 -veined (4), or 6 -veined (2), or 7 -veined (17), or 8 -veined (13), or 9 -veined (15), or 10-11 -veined (4). Lower glume apex obtuse (1), or acute (1), or acuminate (20). Upper glume lanceolate (8), or elliptic (13); 0.8-1.366-2.5 length of adjacent fertile lemma; membranous; without keels; 5-6 -veined (1), or 7 -veined (17), or 8 -veined (14), or 9 -veined (18), or 10-11 -veined (4). Upper glume apex obtuse (1), or acute (1), or acuminate (20).

Morphology Reproductive morphology Flowers Florets

Fertile lemma lanceolate; membranous (1), or coriaceous (20); of similar consistency above (1), or much thinner above (20); without keel; 7 -veined (20), or 8 -veined (4), or 9 -veined (5). Lemma lateral veins distinct (1/1). Lemma surface smooth (13), or scaberulous (5), or scabrous (3); glabrous (13), or pilose (11), or villous (1). Lemma margins eciliate, or ciliate (1). Lemma apex dentate; 2 -fid, or 3-4 -fid (5); acuminate (1/1); muticous (3), or awned (19); 0 -awned (1/19), or 1 -awned (8/19), or 3 -awned (11/19). Principal lemma awn subapical (1/19), or dorsal (19/19); straight (1/19), or curved (2/19), or geniculate (17/19). Column of lemma awn glabrous (14/17), or hispidulous (1/17), or puberulous (2/17), or pubescent (2/17). Lateral lemma awns shorter than principal (11/11). Palea 0.5 length of lemma. Palea keels wingless (19), or winged (2); eciliate (4), or ciliolate (14), or ciliate (3). Palea surface glabrous (20), or pubescent (1).

Morphology Reproductive morphology Flowers

Anthers 3. Ovary pubescent on apex (1), or pubescent all over (20).

Morphology Reproductive morphology Fruits

Caryopsis with adherent pericarp; oblong (1/1). Hilum linear.

Distribution

Europe (17), or Africa (14), or Temperate Asia (13), or Tropical Asia (5), or Australasia (7), or Pacific (3), or North America (4), or South America (7), or Antarctica (1).