Cultivated plants : their propagation and improvement / [Frederick William Thomas Burbridge].

  • Frederick William Burbidge
Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: Cultivated plants : their propagation and improvement / [Frederick William Thomas Burbridge]. Source: Wellcome Collection.

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    and continue the species. The common Lycopodium or Club- moss produces offsets which extend the area occupied by the plant in every available direction ; and the same is true of the tropical Selaginellas and many other flowerless or so-called flowerless vegetables. Seeds and offsets may be considered as nature’s main plan of reproduction; but some plants, the common Bramble for example, are not unfrequently propagated from layers; and the branches and stems of many other plants readily take root when trodden in the earth accidentally by the larger animals. In some cases plants are propagated from cuttings in a state of nature—accidentally perhaps, but still not unfrequently; as when swans and other vegetable-feeding water-birds break off portions of the plants on which they feed, which float away and root elsewhere; or when branches and twigs are broken off by high winds, and fall into moist earth and take root. We have even examples of natural grafting (inarching) in nature, as shown by climbing species of Ficus, or even very frequently in the common Linden-tree and Ivy, where two branches, or the trunk and a branch, become firmly united together. Natural grafting is, however, rarely if ever employed by nature as a re- productive force, but rather as a means of securing additional strength or power of climbing to a stronger support. NATURAL HYBRIDISM. Hybridising and cross-breeding, although generally regarded as artificial methods of propagation as used by man, are never- theless very frequently employed by nature not merely to per- petuate, but also to strengthen and invigorate herself. Thus we see that in many plants especial provision is made to prevent self-fertilisation. This is especially so in the Primrose family, and also among Orchids, Yuccas, and Asclepiads, nearly all of which require insect or other mechanical aid to assist in their fertilisation. But while these plants cannot fertilise themselves, it is often very difficult indeed to prevent cross- breeding, or even hybridisation in others, of which the Cu- cumber and Melon or Cabbage families serve as excellent examples. In the case of the Melon, the male and female organs are borne in separate flowers ; and early in the season, if one variety only be ^own, artificial fertilisation is often neces- sary to enable the fruit to “ set; ” but if two or more kinds are grown, and all flower. together, they set freely without any aid—and, as the gardener is well aware, it is next to impossible to keep any particular variety true; so apt are nearly all Cucur-
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