Ontario Weeds: Wild oats
Excerpt from Publication 505, Ontario Weeds,
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Table of Contents
- Other Names
- General Description
- Stems and Roots
- Flowers and Fruit
- Similar Species
- Related Links
Name: Wild oats, Avena fatua
Other Names: AVEFA, folle avoine, Black oats, avoine folle, avoine sauvage
Family: Grass Family (Gramineae)
General Description: Annual, reproducing only by seed. Very similar to cultivated oats.
Wild oats. A. Base of plant. B. Leaf-base.
Stem and leaf-base characteristics of a typical grass.
Stems & Roots: Stems 60-120 cm
(2-4 ft) high, with distinct dark-coloured nodes: leaves flat, 10-60
cm (4-24 in.) long, often 15 mm (3/5 in.) wide or wider, tapered
to a long thin point, and with a prominent, light-coloured midrib;
leaf sheath without hair or slightly hairy, split, with margins
transparent and overlapping in the lower 2/3 of each leaf sheath;
ligule membranous 2 - 5 mm (1/12-1/5 in.) long; occasionally with
a few prominent hairs on the margins of the collar; no auricles.
Flowers & Fruit: Inflorescence a large panicle with slender branches: spikelets with 2 large papery glumes and usually 2 to 4 florets ("seeds"); florets varying from dull white through yellow or gray to brown or nearly black, usually hairy but sometimes nearly smooth, with a sharp-pointed sucker mouth at the lower end and a long (3-4 cm, 1 1/4-1 5/8 in.), bent, twisted awn. Flowers from June to August.
Habitat: Wild oats occurs in cultivated land on all soil textures throughout Ontario and seems to be increasing. This is one of the most serious weeds in Canada in terms of its competition with annual grain crops.
Similar Species: It is distinguished from tame or cultivated oats by its frequently taller growth, its somewhat yellowish-green inflorescence when compared to the light bluish-green of cultivated oats, and its hairy, dark-coloured, sharp-pointed "seed" having a long, twisted, black awn whereas the seed of cultivated oats is hairless, always a tawny white, lacks a sharp point, and is either without an awn or with a very short straight awn. The seeds of Wild oats shatter very readily when ripe but their germination is delayed, often for several years, in the ground. Cultivated oats normally does not shatter after ripening and its seeds are able to germinate as soon as mature. Some plants of oats have characteristics which are intermediate between the wild and cultivated kinds. These have been called "False wild oats" and "Dormoats" and may be hybrids between the two types.
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