Avena fatua L.
wild oat
Tall, green or light green tufts to 1.5 m, robust, or sometimes with rather slender culms. Leaf-sheath slightly hairy, upper sheaths glabrous. Ligule 2-7 mm, truncate to oblong and obtuse, denticulate, abaxially scabrid. Leaf-blade 15-50 cm × 4-15 mm, scabrid on ribs and margins, often with scattered hairs, especially on margins. Culm erect or occasionally geniculate at base, internodes glabrous. Panicle (15)-20-38 cm, lax, equilateral, ± nodding; branches widely spreading, slender, drooping, scabrid. Spikelets 35-50 mm, 2-3-flowered, pendulous on fine unequal pedicels; disarticulation below each floret at maturity. Glumes 9-11-nerved. Lemma 15-17.5 mm, narrow-lanceolate, light brown at first becoming tough and darker brown at maturity, stiffly hairy below level of awn insertion, or sometimes glabrous, scabrid on nerves above, narrowed to bidentate scarious apex; awn 30-40 mm, geniculate, stout, column dark brown, twisted. Palea keels with one row of cilia, interkeel scabrid. Callus with horse-shoe shaped scar densely bordered by long hairs. Anthers 2.5-3.5-(4) mm. Caryopsis 6-8 × 1.8-2.2 mm, light grey, densely hairy.
N.: Auckland City, Bay of Plenty (Opotiki), Hawkes Bay (Takapau), more common in the Manawatu and Wairarapa, also from near Wellington City; S.: common in Canterbury, North and Central Otago, less so in Nelson, Marlborough, South Otago and Southland; Ch. A problem weed of crops, on roadsides and waste land and also in brackish soil and reclamation areas.
Naturalised.
Occasional hybrids A. fatua × A. sativa may occur within an oat crop, or where oats have been grown. The two spp. are strongly self-fertilising and few hybrids are found.
Indigenous to Europe, Central Asia and North Africa; now naturalised and a widespread weed in temperate regions of both Hemispheres.
