The vine requires a high summer temperature and a prolonged
period in which to ripen its fruit. Where these are
forthcoming, it can be profitably cultivated, even though the
winter temperature be very low. Tchihatchef mentions that
at Erivan in Russian Armenia the mean winter temperature
is 7° 1΄ C. and falls in January to -30° C., and at Bokhara the
mean temperature of January is 4° C. and the minimum -22° C.,
and yet at both places the vine is grown with success. In the
Alps it is profitably cultivated up to an altitude of 1870 ft.,
and in the north of Piedmont as high as 3180 ft. At the present
time the limit of profitable cultivation in Europe passes
from Brittany, lat. 47° 30΄, to beyond the Rhine by Liege and
through Thuringia to; Silesia in lat. 51° 55'. In former
centuries vines were cultivated to the north of this region, as,
for instance, in Holland, in Belgium largely, and in England,
where they might still be grown. Indeed, experiments have
been made in this direction near Cardiff in South Wales. The
yield is satisfactory, and the wine made, the variety known as
Camay noir, is described as being like still champagne. In
the middle ages, owing to various causes, the better wines
of France and Germany could not be obtained in England
except at prohibitive prices; but when this state of things
ceased, and foreign wine could be imported, the English consumers
would no longer tolerate the inferior productions of
their own vineyards. It is also probable that the English
mixed sugar or honey with the wine and thus supplied artificially
that sweetness which the English sun denied. It is a curious
fact that at the present day much or even most of the wine
of finest quality is made at or near to the northern limits of
possible cultivation with profit. This circumstance is probably
explained by the greater care and attention bestowed both
on the cultivation of the vine and on the manufacture of the
wine in northern countries than in those where the climate
is more propitious. The relative inferiority of the wines made
at the Cape of Good Hope and in Australia is partly due to
variations of climate, the vine not yet having adapted itself
to the new conditions, and partly to the deficient skill of the
manufacturers. That such inferiority may be expected to
disappear is suggested by the success of vine-culture in Madeira
and the Canary Islands.
The development of other species of Vitis, such as the curious succulent species of the Soudan and other parts of equatorial Africa, or the numerous kinds in India and Cochin China, is of course possible under suitable conditions; but it is obvious that an extremely long period must elapse before they can successfully compete with the product of many centuries.
[See also generally the article Wine. For currants and raisins, both produced by varieties of the grape-vine, see the respective articles.]
Apart from their economic value, vines are often cultivated for purely ornamental purposes, owing to the elegance of their foliage, the rich coloration they assume, the shade they afford, and their hardihood.
Vines have woody climbing stems, with alternate, entire or palmately lobed leaves, provided at the base with small stipules. Opposite some of these leaves springs a tendril, by aid of which the plant climbs. There are numerous transitional states between the ordinary form of tendril and the inflorescence. The flowers are small, green and fragrant, and are arranged in dense clusters. Each has a small calyx in the form of a shallow rim, sometimes five-lobed or toothed; five petals, which cohere by their tips and form a cap or hood, which is pushed off when the stamens are ripe; and five free stamens, placed opposite the petals and springing from a fleshy ring or disk surrounding the ovary; each bears a two celled anther. The anomalous position of the stamens in front of the petals is explained by the abortion or non-development of an outer row of stamens, indications of which are sometimes seen on the hypogynous disk encircling the ovary. The ovary bears a sessile stigma and is more or less completely two-celled, with two erect ovules in each cell. This ripens into the berry and seed. The cultivated vine has usually hermaphrodite flowers; but as it occurs in a wild state, or as an escape from cultivation, the flowers manifest a tendency towards unisexuality; that is, one plant bears flowers with stamens only, or only the rudiments of the pistil, while on another plant the flowers are bisexual. Exclusively female flowers without stamens do not appear to have been observed. Seedling plants from the cultivated vines often produce unisexual flowers, thus reverting to the feral type. Perhaps the explanation of the fact that some of the cultivated varieties are, as gardeners say, "bad setters,"—i.e. do not ripen their fruit owing to imperfect fertilization,—is to be sought in this natural tendency to dioecism.
Fig. 1.—Vine.
1. Foliage, tendril and inflorescence, reduced.
2. Flower after fall of petals, magnified.
3. Fruit, reduced.
The conformation of the vine stem has elicited a vast amount of explanatory comment. The most generally accepted explanation is the "sympodial" one. According to this, the shoot of the vine is a "sympodium," consisting of a number of "podia" placed one over the other in longitudinal series. Each podium consists of a portion of the stem bearing one or more leaves, each with an axillary bud or buds, and terminating in a tendril or an inflorescence. In V. Labrusca there is a tendril opposite to each leaf, so that the podium bears only a single leaf. In other species there is a definite arrangement of the leaves, some with and others without tendrils opposite to them, the numerical order remaining constant or nearly so. These arrangements have doubtless some reference to climatic phenomena, continuity of growth being arrested by cold and promoted by warmth. In any case, it is obvious that these facts might be turned to practical ends in cultivation. A vine, for instance, that produces bunches of grapes at each joint is preferable to one in which there are several barren joints, as a larger quantity can be grown within a smaller area. The practice of pruning or "stopping" is, consciously or unconsciously, regulated by the mode of growth. The tendril or inflorescence, according to the views above explained, though in reality terminal, is bent to one side; hence it appears to be lateral and opposite to the leaf. While the tendril is thus diverted from its original direct course, the axillary bud of the leaf opposite the tendril begins a new podium, by lengthening into a shoot which assumes the direction the tendril had prior to its deflexion. This new podium, now in a direct line with its predecessor, produces leaves and ends in its turn in a tendril or inflorescence. A third podium succeeds the second, and so on. Other authorities explain the formation of the tendril and its anomalous position opposite to a leaf by supposing that the end of the stem bifurcates during growth, one division forming the shoot, the other the tendril or inflorescence. It is not possible within the limits at our command to specify the facts and arguments by which these theories are respectively supported. Practically the tendrils assist the plant in its native state to scramble over rocks or trees. As in the case of similar formations generally, they are endowed with a sensitiveness to touch which enables them to grasp and coil themselves round any suitable object which comes in their way, and thus to support the plant. The seeds or grape-stones are somewhat club-shaped, with a narrow neck-like portion beneath, which expands into a rounded and thickened portion above. On the inner or central side of the seed is a ridge bounded on either side by a shallow groove. This ridge indicates the point of union of the "raphe" or seed-stalk with the seed; it serves to distinguish the varieties of V. vinifera from those of other species. In endeavouring to trace the filiation and affinities of the vine, the characters afforded by the seed are specially valuable, because they have not been wittingly interfered with by human agency. Characters derived from the size, colour or flavour of the berry are of less value for
