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GRASSES OF THE COLUMBIA BASIN OF BRITISH COLUMBIA Heather Stewart, Richard Hebda Major Groups of Grasses Table of Contents Glossary Avena Oats Oats (called Avena in Latin) comprise a small group of species from the Old World. They have large, drooping flowerheads and stout, twisted, bent awns growing from the back of the lemmas. Avena Adapted from Douglas et al. (1994) 1a. Lemmas are hairy with bent awns on the lower two lemmas; awns extend from the spikelet.........................................................................................................................Avena fatua 1b. Lemmas are smooth with straight awns on the lower lemmas or are awnless. .....................................................................................................................................Avena sativa   Avena fatua L. Wild Oat Plant: Avena fatua is an introduced species that grows to 80 cm tall. It is an annual with large, open, drooping flowerheads. Leaves and Stem: The sheaths are open and there are no auricles. The membranelike ligules are 3-6 mm high and have a hairy upper edge. The flat leaf blade is 3-10 mm wide and feels rough due to scattered long hairs. Flowerhead and Flowers: The open flowerhead has two or three flowers per spikelet. The membranelike glumes are equal and extend past the flowers. The flowers readily break from the stem axis at maturity above the glumes. The lemmas are hardened, densely hairy at the base near the callus. The pointed callus is covered in a dense beard. The lemma point is membranelike and has two teeth that are 1mm long. The first two flowers have twisted and bent awns that are up to 4 cm long. Habitat: Wild Oat was introduced from Eurasia. It occurs most often on waste ground, and is a weed in grain fields. In the Columbia Basin region it grows at Creston and Yoho National Park. Similar Species: Wild Oat resembles Common Oat (Avena sativa), but Wild Oat has a more hairy lemma and a long, bent awn, whereas Common Oat does not. The lemma tip on Common Oat is thickened, unlike Wild Oat, which has a thin membranelike tip. Avena sativa L. Common Oat Plant: Avena sativa is an introduced species that grows to 80 cm tall. It is an annual with large, open, drooping flowerheads. Leaves and Stem: The sheaths are open and there are no auricles. The stem ranges from smooth to rough. The membranelike ligules have 2-4-mm-high hairs along the edge. Flowerhead and Flowers: The open pyramid-shaped flowerhead has spikelets that are two to three flowered. The glumes are unequal and exceed the flowers in length. The lemmas are smooth and thickened at the tip. The lemma tip may have two shallow teeth at the tip. The callus may be either bearded or naked. When present, the lemma awn is 15 mm longer than the lemma and is not bent. The lemma of the first flower can be awned, but there is no awn on the second flower. Habitat: Common Oat grows on roadsides, railways and waste places. Introduced from Eurasia, it does not persist as an escape from cultivation for more than a year. In the Columbia Basin region it was only collected at Kokanee Glacier Park. Similar Species: Common Oat resembles Wild Oat, but Common Oat has a less hairy lemma and does not have a bend in the awn. The lemma tip on Common Oat is thickened and firm, unlike Wild Oat, which has a thin membranelike tip.

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