Agrostis canina, L., is somewhat larger than A. alba. Palea (only one present, sometimes minute) punctate, 2 mm., with a fine dorsal awn a little longer than the palea. Caryopsis 1·2 mm. Rachilla obsolete.
The awn is usually absent from A. alba and its varieties; and when present is so small as to be almost negligible.
A. canina is easily distinguished from Poa by the rachilla in the latter, and absence of awn. Aira has basal hairs, &c.
Agrostis setacea, Curt., has the awn basal and just projecting beyond the pointed glumes, and the palea very minute, with a few silky hairs below.
Agrostis Spica-venti, L. (Fig. [49]).
Palea 2·4 mm. long, with infolded edges and punctate; a minute rachilla at its base, and a slender awn, 8-9 mm. or more long, inserted below the bifid tip. Caryopsis 1·5 mm. A few silky hairs at the base of the palea.
(b) Awn terminal or slightly sub-terminal, and straight, or at least not twisted or “kneed."
(1) Paleæ so closely adherent to the fruit that the terminal awn appears to come from the latter [Barley type]. The three florets generally coherent.
✲ Awn at least twice the length of the grain.
Hordeum sylvaticum.
H. murinum.
Hordeum sylvaticum, Huds.
Palea scabrid, ribbed above, awn at least twice as long as the very narrow grain.
Hordeum murinum, L.