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Info
Subfamily: Pooideae
Genus etymology: Arrhenatherum = "male spine" [Greek] refering to the upper floret being male and awned
Species etymology: elatius = "taller" [Latin] refering to its height
Photosynthetic type: C3 (cool season)
Nativity: naturalized - intentional
First recorded in Hawaiʻi: 1904
Map
Inflorescence
image credit: Alexis_OrionPlant
image credit: Forest & Kim StarrHabit
image credit: Forest & Kim StarrDescription
Plants loosely cespitose, sometimes rhizomatous, rhizomes to 3 mm thick. Culms 50-140 (180) cm, erect, glabrous, unbranched, basal internodes swollen or not; nodes usually glabrous, occasionally puberulent to densely hairy. Sheaths smooth; ligules 1-3 mm, obtuse to truncate, usually ciliate; blades 5-32 cm long, (1)3-8(10) mm wide, flat, usually glabrous, rarely shortly pilose, sometimes scabrous. Panicles 7-30(36) cm long, 1-6(10) cm wide, green, shiny, becoming stramineous, sometimes purple-tinged; branches 15-20 mm, ascending to divergent, verticillate, usually spikelet-bearing to the base; pedicels 1-10 mm. Spikelets 7-11 mm; rachillas stout, internodes to 0.7 mm, prolongations 1.2-2 mm, slender, apices often with a small, club-shaped rudiment. Glumes lanceolate to elliptic; lower glumes 4-7 mm; upper glumes 7-10 mm; callus hairs to 3.7 mm; lemmas (4)7-10 mm, apices bifid; awns of lower lemmas 10-20 mm, twisted below, often with alternating light and dark bands; awns of upper lemmas absent or to 5 mm and arising just below the apices, rarely to 15 mm and arising from above the middle; paleas 0.5-1 mm shorter than the lemmas, acute; anthers 3.6-5(6) mm. Caryopses 4-5 mm long, about 1.2 mm wide, ellipsoid, densely hairy, yellowish. 2n = 14, 28, 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/Arrhenatherum_elatius )