From these experiments, then, we may conclude that different types of crop oats are derived from the Avena fatua, or wild oat; but, besides this, they open out a subject for inquiry of great practical interest and importance, which may be clearly stated as follows:—
If by cultivation the wild oat assumes the cultivated form, then by degeneracy cultivated oats may become wild ones.
Those who know what a detestable weed is the wild oat wherever it occurs, and how difficult it is to eradicate,[11] will at once see the cogency of the question involved.
[11] The author once went with a rector of a parish in Gloucestershire to examine the glebe allotments of the poor people, when, catching sight of an apparent crop of oats, the landlord threatened to dispossess the tenant, “because he had carelessly left his crop without gathering.” However, the matter was explained when it was pointed out that the land was planted with wheat, which the oats had quite smothered.
Farmers in some districts, and more especially on stiff clay soils, have ever objected to the cultivation of oats, as they had always maintained that they left behind a crop of weed oats. This, which was never a favourite idea with the botanist, who is generally too much inclined to species-making, seems now to have a basis of truth, for not only is it confirmed by the experiments described, but observation of an independent kind points to the same truth.
On examining the produce of shed, or accidentally scattered oat seeds, the first crop will often present the wild tendency in a partial reversion to the hairy state, an elongation and thickening of the awn, and a lessening of the size of the kernel; and this more particularly on heavy soils. It was, indeed, an observation of this change in oats scattered on forest marble clay which induced us to try the experiments above detailed; and as the subsoil of our botanical garden is the same clay, we are, perhaps, indebted to this cause for arriving so soon at such signal results.
Again, it is known in farming that some clay lands will never produce heavy oats; a sample, however good, is sure to degenerate upon such soils. Hence, then, the foregoing experiments and observations lead to the following conclusions:—
1st. The wild oat is perhaps not a native of Britain, but derived through the degeneracy of the cereal crop; and hence its occurrence only as an agrarian.
2nd. The cereal oat, on the contrary, is the result of the impress of cultivative processes upon the wild form, and as such liable to lapse into the wild state with greater or less celerity, according to the circumstances of soil and situation.
These conclusions are of practical value, as they show the direction in which experiments should be conducted in order to attain to varieties, it being a well-known fact that one variety is suitable for one soil, and another for a different kind of land. And again, as some forms of plants would seem to have the tendency of wearing out by long cultivation, so we have the means of applying to the original source of their production, and thus of commencing a new generation.
They teach us, too, the necessity of avoiding the growth of the oat crop in some situations, and which in the case before us is not the result of the “pigheadedness” with which the farmer is often so thoughtlessly accused, but a conclusion founded in reason; and if we consider how robust is the growth of the wild oat, and that its support is secured by robbing the grain crop with which it occurs as a weed—the difficulty of separating it from the crop where it has gained a footing—and, above all, that its succession is secured by its seeds universally ripening a few days before that of the crop with which it is mixed, and the moment they are ripe they fall and become self-sown,[12]—we can see abundant reason for wholesome fear as to the introduction of cereal oats in districts liable to their degeneracy.