Melica uniflora, also a wood-grass, has the spikelets two-flowered, though the upper one may be a mere rudiment, and much fewer, on a flexuous nodding axis. The much rarer M. nutans has two perfect flowers in the spikelet (see p. [105]).
(ii) Grasses of open situations, with numerous small pointed spikelets. Inner palea minute or absent.
Agrostis.
The genus most likely to give trouble here is Aira, which though normally with two flowers in the spikelet, occasionally has but one. As regards the common species of similar habit, &c., Aira has bristle-like leaves and Agrostis flat ones.
Again, Agrostis alba has no protruding awn, as in the spikelets of Aira. For Aira cæspitosa and other details, see p. [117].
✲ Awnless, or at most a short bristle not equalling the palea. Leaves flat and short.
A. alba, L.
An exceedingly variable plant. The variety A. stolonifera has a less spreading panicle, and broader leaves with a long serrated and pointed ligule: the variety A. vulgaris has a spreading loose panicle, narrower leaves, and a short truncated ligule. There is, however, much difficulty in distinguishing the intermediate forms on mountain-pastures, &c.
✲✲ Distinctly awned. Leaves narrower, the lower ones inrolled and almost setaceous.
A. canina, L.
The rarer A. setacea, Curt. with subulate leaves and A. Spicaenti, L. with long awns also come here.
The lax spreading type of panicle characteristic of Aira and Agrostis, &c., described above, occurs in species of Avena, Bromus, Briza, Poa and Catabrosa, but the basal silky hairs and twisted awns (Avena), long sub-terminal bristle-awns (Bromus), habit (Catabrosa), and the presence of two, three, or more flowers in the considerably larger spikelets of all, easily distinguish them.
The rare grasses Leersia, with two glumes and no paleæ, and Gastridium, with curiously bullate bases to the glumes, also come into this group with one-flowered spikelets, but their characters must be studied with the flora. The same remark applies to species of Panicum, Cynodon, Spartina and other aliens, occasionally met with.