WHEAT: ITS ORIGIN AND ACCLIMATIZATION.
It is a popular belief that wheat, in a state fit for food, was a direct
gift to man, and handed down to him unaltered in form, except in so far
as relates to varieties; but if we consider how varied are the details
of this plant, how very different from each other are the more remote
varieties, and yet how easy it is to fill up the links on the one hand,
or to arrive at equally distinct and yet new forms on the other, we can
only conclude that wheat, like most, if not all, our vegetable
esculents, is but a _derivative_ plant obtained from a wild form of
grass, and in very early times brought into cultivation because of the
facilities for change which it was capable of undergoing.
Nowhere is wheat, as such, found wild; for, although its grain has been
cultivated in all parts of the world, its scattered seeds cannot
maintain a position for any length of time; for, as it has been obtained
by cultivation, so its derived status can only be maintained by careful
culture, without which there seems reason to believe that cereal wheat
would indeed become extinct.
Many botanists had arrived at these or kindred views from observation
and reasoning upon the subject, but it was not until a comparatively
recent period that we possessed any direct evidence derived from
experiment: this we now have, and upon it we quote the following from
Mr. Bentham, in the _Cyclopædia of Agriculture_, article “Triticum”:—
It has never been contended that their original types have become
extinct, and various, therefore, have been the conjectures as to
the transformations they may have successively undergone; and as no
accidental returns towards primitive forms have been observed, we
have till lately had but little to guide us in these vague
surmises. Within the last few years, however, the experiments and
observations of M. Esprit Fabre, of Agde, in the south of France,
seem to prove a fact which had been more than once suggested, but
almost always scouted, that our agricultural wheats are cultivated
varieties of a set of grasses common in the south of Europe, which
botanists have uniformly regarded as belonging to a different
genus, named _Ægilops_. The principal character by which the latter
genus had been distinguished, consisted in the greater fragility of
the ear, and in the glumes (_i.e._ the chaff-scales) being
generally terminated by three or four, and the pales by two or
three points or awns (beards). But M. Fabre has shown how readily
these characters become modified by cultivation; and, wide as is
the apparent difference between _Ægilops ovata_ and common wheat,
he has practically proved their botanical identity; for, from the
seeds of the _Ægilops_ first sown in 1838, carefully raised in a
garden soil, and re-sown every year from their produce, he had,
through successive transformations, by the eighth year (1846)
obtained crops of real wheat as good as the generality of those
cultivated in his neighbourhood.
It was the description of the experiments of M. Fabre, in the _Journal
of the Agricultural Society_, which led us to institute independent
inquiries, to which end, having purchased some seeds of _Ægilops ovata_,
we sowed them in our experimental garden at Cirencester, in a prepared
plot of five yards square, on a subsoil of forest marble. From this
seeds were selected to carry on the experiments, whilst the mass of the
plants in the plot were allowed to seed and come up spontaneously, which
it did year after year, and so preserved the original type with which
we started. The preserved seeds were sown in fresh plots year by year,
but—perhaps owing to the coldness of the soil and the general lower
climate of the Cotteswolds—progress was only slow at first; however, in
the warm summer of 1859 our plot of the season had made fresh advances,
which will be best understood by an examination of the accompanying
drawings.
Fig. 3 represents a spikelet of the type of _Ægilops ovata_, introduced
into our garden in 1855. In this some of the pales have double awns,
others single ones. Fig. 4, a spikelet of 1859, modified by cultivation.
In this the awns are single. Fig. 5, a spikelet from an ear of bearded
wheat.
Now, the close affinity of these three forms must strike any one; but we
feel justified in concluding that, had not our experiments been
peremptorily stopped, and the results, as far as possible, spoiled from
the ignorance and jealousy of the new Principal, we should before this
have arrived at results much more satisfactory.
The principles of the observed changes will be understood by stating the
following facts.
_a._ _Ægilops ovata_ has a seed of sufficient size to be called a corn
grain, and which, though not so large as that of wheat, yet rapidly
improves by cultivation, which includes selection.
_b._ The _rachis_ (the part on which the spikelets are placed in the
wild grass) is exceedingly brittle, so that it readily breaks into bits
below each spikelet; this brittleness annually gets less under
cultivation.
_c._ The wild grass has a trailing habit of growth; but uprightness and
a longer culm is at once induced by the closer contact of drilling the
seeds in thick rows.
_d._ The cultivation of _Ægilops_, and especially subjecting it to rich
soil, produces the same kinds of fungoid attacks as are found with
wheats under like circumstances, as thus:—_Puccinia graminis_ (mildew)
of the leaves and culms; _Uredo rubigo_ (red rust) of the chaff-scales;
_Uredo caries_ (smut or bunt) of the grain.
Now, all these circumstances seem to point to a similarity in essential
structure, and a uniformity of habit somewhat remarkable in plants which
at first sight would strike one as being so different; but as these
differences between _Ægilops_ and any variety of wheat are often all
scarcely greater than is to be met with on contrasting two known
varieties of wheat, we may agree in concluding that the evidence
warrants the assumption that wheat, as a cultivated cereal, has been
derived from _Ægilops_.
If, then, we view the wheat plant as a derivative, we shall be at no
loss in understanding how the vast number of varieties have been brought
about—varieties applicable, too, to a wide range of climatal conditions;
and the ease with which new forms can be brought about by hybridization
and selection is a matter of importance, because older varieties, too
often repeated, are apt to degenerate both in quality of grain and
quantity of crop. But when we speak of acclimatizing wheat, we think it
would be excessively difficult to make any existing form grow well in a
climate not congenial to it, though it might be easy to arrive at a new
variety possessing some desired quality. We believe, however, that it is
not difficult to alter a climate to suit a sort, and, in all
probability, this at the present day much-used term of “acclimatization”
simply means no more than making our cultivation and climate accord as
nearly as possible to the habits of the plant or animal to be
entertained under new conditions.
Thus, when we see the finer white wheats growing good crops on farms
where such would have been impossible a few years ago, we are hardly to
conclude that we have at length got this more delicate sort to become
more hardy; but the climate has been ameliorated by draining and better
cultivation.
We distinctly recollect when the lias clays of the Vale of Gloucester
could scarcely be made to grow a good crop of even the hardier sorts of
red wheat, the common cone being the sort generally grown. This was
succeeded by many sorts of red wheat, and now only the best-cultivated
farms produce white wheats. These, however, are facts which will be more
strongly brought out when we consider the subject of cultivation; for
the present we would be content with the expression of a belief that
wheat, as a cereal grain, is derived by cultivation from a wild grass,
and it is due to the effects of cultivation that we have so many sorts,
with such variable adaptability.