Our next diagram shows the progress of dodder-growth when the parasite has germinated sufficiently near to a young flax plant to be attracted to it. In such case, instead of dying, it seems all at once to be animated by new vigour. The highly elastic thread, which now represents the whole dodder plant, goes through the following stages:-

[Ill.u.s.tration: A. The dodder, having just clasped a flax plant, has made two coils round the stem of the latter.

B. Meanwhile the flax in growing lifts the dodder out of the soil.

C. While the flax is getting still taller, the dodder sends out rootlets, which pierce and fix themselves into the flax. During this the dodder sends out buds upwards, which, elongating until new flax plants are met with, explains not only how the dodder commences a growth quite independent of the soil, but, by spreading, from plant to plant, thus increases to an indefinite extent.]

In this way, then, the dodder of flax, commencing from seeds at different points, spreads in more or less extended patches, which, if such centre be few, will be distinct; if many, the pest may occupy the greater part of the crop by spreading, and so becoming confluent.

Such is the method of growth of flax dodder, and we have no doubt but that the dodder of the clover progresses in like manner; at all events, we see the latter occupying more or less isolated patches in the affected crop; and in this case, as in the former, the crop-plant is not only starved, from having "its verdure sucked out," but it is borne down to the ground and ruined.

As regards its destruction, we should be careful to look at our crops in their early growth, as, if the sickly-looking, wire-like tendril be observed then, it is easily removed by hand; if, however, it has made head, the best way would be to make a trench of a foot wide around the plague-spots, which will prevent its spreading, as the plant must have contiguous clovers to twist round if it is to extend; and then burn some straw on the dodder plot, and it will be wasted to death. Probably, however, the easiest plan is to depasture the crop,-certainly not to seed it down-in which case it will be impossible for any dodder seeds to ripen.

But here, as in other cases, the evil will be prevented by sowing pure seed, whether of flax or of clover; and as the dodder is a small, brown, roundish little seed, so different from that of either crop, there is no difficulty in recognizing it where present.

OROBANCHE-_Broomrape_.

The Broomrape is now becoming a very pernicious clover weed, especially in lighter soils. We have seen it on clover near Stonehenge so thick as to have positively spoiled the crop; and we should expect from its bitter, disagreeable flavour, that if cattle did not universally refuse to eat it, it might prove mischievous to them.

The species which attacks clover is the _Orobanche minor_-Lesser Broomrape,-which is at once distinguished in a clover field by its upright brownish spike of dead, dry-looking, lipped flowers; the stem without true leaves, but clothed with small brown leaf-like processes (_bracts_ of the botanist), which, with the stem, are clothed with hairs.

This plant, which is much larger and very different from the clover, is parasitic on the princ.i.p.al division of the clover root; so that if the soil be carefully removed from the broomrape, it will be found to swell at the base, into which the clover root may be detected to be fastened, and a very odd appearance indeed has the small-stemmed clover united to so comparatively large a parasite.

The seeds of the broomrape are so small as scarcely to be detected in a sample of clover seed; indeed, several may be fastened to a seed as dust, so that whatever care may be used in the selection of seed will hardly prevent this pest. Any great injury to the clover crop may be speedily stopped by hand-picking the broomrape; for, although it will sometimes branch up again, it will be much lessened, and the few secondary shoots will usually be very weak.

Clovers are attacked by _Epiphytes_-that is, minute fungoid plants growing upon the leaves; but the natural history of these is too obscure for a general treatise, nor are they of sufficient interest to the practical farmer.[9]

[9] To such as may be interested in the study of the "rusts" of Clover, and some other plants, we would earnestly recommend a perusal of some most interesting papers on the subject, by M. C. Cooke, Esq., beautifully ill.u.s.trated by Messrs. West & Sowerby, which will be found in the _Popular Science Review_-a serial which should have a place in the house of every country gentleman.

[Ill.u.s.tration: Corn.]

HOW TO GROW GOOD CORN.

CHAPTER XXIV.

NATURE OF CORN.

By corn, in its enlarged sense, the farmer means all such crops as are grown for their seeds; so that all kinds of grain and pulse, such as peas and beans, belong to the corn crop, as distinguished from roots and green crops. In America the word "corn" is restricted to maize or Indian corn, and other crops are called after their respective names. Our dictionaries define corn as "seeds which grow in ears, not pods;" and it is to these that the present treatise is meant exclusively to apply, confining our remarks for the most part to such kinds as are more commonly cultivated in this country.

Corn, then, may be said to be derived from different species of gra.s.ses, whose seeds are sufficiently large to enable them to be threshed from the ear and become stored as grain, in which case it differs from the smaller kinds, whose seeds may be grown for pasturage crops.

Hence, then, gra.s.ses afford us two sets, which are differently used,-one, as affording corn fabled to be the gift of the G.o.ddess Ceres, and so called cereal or corn gra.s.ses; the other, not grown for the sake of the grain, but for herbage, and named meadow and pasture gra.s.ses.

Corn gra.s.ses, then, belong exclusively to arable cultivation; and, indeed, it may be concluded that such have been derived from wild species, and that continued culture has brought them about, and still maintains them in all their endless varieties, and also gives us a power to add to these to an extraordinary extent.

It is this facility for improvement, this capability for forming grain on the one hand, and running into varieties on the other, which enables corn to be grown under so wide a range of temperature and in such varied and variable climates; and it is a knowledge of the laws affecting these changes, and the modes of action in the growth of corn consequent thereupon, which will const.i.tute "Science and Practice in Corn Cultivation," and should lead to a knowledge of "How to Grow Good Corn."

In following out this inquiry, we shall, for the most part, confine our observations to the following crops:-

1. Wheat, } 2. Oats, } Their Origin, Cultivation, Diseases, 3. Barley, } Enemies, &c. &c.

4. Rye, }

CHAPTER XXV.

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 gra.s.s, 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 _Cyclopaedia of Agriculture_, article "Tritic.u.m":-

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 gra.s.ses common in the south of Europe, which botanists have uniformly regarded as belonging to a different genus, named _aegilops_. The princ.i.p.al 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 _aegilops ovata_ and common wheat, he has practically proved their botanical ident.i.ty; for, from the seeds of the _aegilops_ 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 inst.i.tute independent inquiries, to which end, having purchased some seeds of _aegilops 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 ma.s.s 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 _aegilops 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 Princ.i.p.al, 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._ _aegilops 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 gra.s.s) is exceedingly brittle, so that it readily breaks into bits below each spikelet; this brittleness annually gets less under cultivation.

_c._ The wild gra.s.s 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 _aegilops_, and especially subjecting it to rich soil, produces the same kinds of fungoid attacks as are found with wheats under like circ.u.mstances, as thus:-_Puccinia graminis_ (mildew) of the leaves and culms; _Uredo rubigo_ (red rust) of the chaff-scales; _Uredo caries_ (s.m.u.t or bunt) of the grain.

Now, all these circ.u.mstances 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 _aegilops_ 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 a.s.sumption that wheat, as a cultivated cereal, has been derived from _aegilops_.

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 quant.i.ty 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.