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Info
Subfamily: Pooideae
Genus etymology: Avena = "oat" [Latin]
Species etymology: sativa = "cultivated" [Latin] refering to this being domesticated
Photosynthetic type: C3 (cool season)
Nativity: naturalized - intentional
First recorded in Hawaiʻi: 1871
Map
Inflorescence
image credit: Patrick_HackerPlant
image credit: Markus_KriegerSpikelets
image credit: Jo_RobertsDescription
Plants annual. Culms 35-180 cm, prostrate to erect when young, becoming erect at maturity. Sheaths smooth or scabridulous; ligules 2-8 mm, truncate to acute; blades 8-45 cm long, 3-14 (25) mm wide, scabridulous. Panicles (6)15-40 cm long, 5-15 cm wide, nodding. Spikelets (18)25-32 mm, to 50 mm in 'naked oats', with 1-2 florets (to 7 in 'naked oats'); disarticulation not occurring, the florets remaining attached even when mature. Glumes subequal, (18)20-32 mm, 9-11-veined; calluses glabrous; lemmas 14-18 mm, usually indurate, membranous in 'naked oats', usually glabrous, sometimes sparsely strigose, apices erose to dentate, longest teeth 0.2-0.5 mm, usually unawned, sometimes awned, awns 15-30 mm, arising in the middle 1/3, weakly twisted, not or only weakly geniculate; lodicules with a lobe or tooth on the wings, this sometimes very small; anthers (1.7)3-4.3 mm. 2n = 42.
(Description source: Barkworth, M.E., Capels, K.M. & Long, S. (eds.) 1993. Flora of North America, north of Mexico. Volume 24. Magnoliophyta: Commelinidae (in part): Poaceae, Part 1. Oxford University Press, New York. 911 pp. http://floranorthamerica.org/Avena_sativa )
Stout annuals; culms (2.5-)4-8(-12.5) dm tall. Sheaths glabrous, with margins overlapping; ligule 2-5.5 mm long, obtuse, puberulent, finely erose-ciliate; blades (4-) 5-10(-17) mm wide. Inflorescences paniculate, 12-30 cm long, open; spikelets 2(3)- flowered, rachilla glabrous or sparsely hirsute, not readily disarticulating above glumes and between florets; glumes usually exceeding florets, 9-11(-13)-nerved, first glume (17-)18-26 mm long, second glume (18-)20-28 mm long; lemmas (12-)14-20 mm long, glabrous to sometimes scabrous, 3-7-nerved, the nerves obscure on the indurate, yellowish brown lower part and prominent on the herbaceous upper 1/3, apex entire or very shallowly bilobed, callus naked or only sparsely bearded, awns, when + present, on first floret, (15-)22-35 mm long, not geniculate; palea firm, the 2 keels ciliate. Caryopsis pale brown, ellipsoid, ca. 1 cm long, ca. 2.5 mm wide, appressed pubescent. [2n = 20, 40-42, 48, 63.]
(Description source: O’Connor, P.J. 1990. Poaceae, pp. 1481–1604. In: Wagner W.L., Herbst D.R. & Sohmer S.H. (eds.)., Manual of the flowering plant of Hawaiʻi. Vol. 2. University of Hawaii Press & Bishop Museum Press, Honolulu )