(b) Blade and sheath glabrous or merely ciliate or silky, the former tending to twist to the right.
Oat.
Auricles filiform. The plumule emerges above. The embryo has three roots.
A curious phenomenon is observed in some grasses growing in high latitudes, or mountainous regions, or in moist situations. The flowers, or even entire spikelets, grow out into minute leafy buds, with rudimentary roots at the base, and fall off like the bulbils of other monocotyledons, taking root directly in the damp soil. The phenomenon must be looked upon as a case of apogamy, since the development of sexual organs is entirely passed over; the parts which would normally have become ovary and stamens being transformed into leaves. In some species or varieties—e.g. Poa alpina, Festuca ovina—this viviparous condition may coexist with normal flowers and spikelets; in others—e.g. Poa laxa, var. stricta—only the viviparous state occurs.
In the following arrangement the student should note that the terms “Seed" and “Fruit" are used in the ordinary sense of the farmer and seedsman: by the former is meant the “seed" as it comes in samples into the market, when the true fruit or grain (Caryopsis) is almost invariably invested by adherent “chaff"—i.e. paleæ or glumes or both. When the word Caryopsis is employed, I mean it strictly in the botanical sense explained above. In Hordeum, for example, we never see the true fruit, the grain consisting of the caryopsis with paleæ so closely adherent to it, that we are apt to take them as part of the grain itself. The true seed, in the strict botanical sense, is never seen as a naturally separate organ in our native grasses; and, as already explained, only very few exotic grasses ever shed it—e.g. Sporobolus.
CHAPTER IX.
CLASSIFICATION OF GRASSES BY THE "SEEDS" (GRAINS).
I. “Seed" rounded (Millet-seed[12] type). Caryopsis ovoid or sub-globose, devoid of distinct groove, and distending the awnless paleæ, or falling out free.
A. Glumes cuspidate, “fruit" yellowish.
Phleum pratense.