334 



CASSELL'S POPULAR GARDENING. 



The varieties of the garden Pansy are believed to 

 be the descendants of Viola tricolor intercrossed with 

 V. Altaica, grandijiora, and lutea. There has been 

 great controversy as to whether such is the case, 

 and whether the so-named forms are varieties of 

 one species. With regard to the last, it is im- 

 material whether we regard them as species or 

 not, seeing that centuries of domestication have 

 effected marvels in breaking down barriers at 

 one time believed impassable. Again, in a state of 

 nature we find V. tricolor extremely variable as to 

 colour in different parts of the country, so that 

 within this species itself we have all the material 

 necessary for the manufacture of a practically un- 

 limited amount of forms, which we have merely to 

 improve by intercrossing and selection. The greatest 

 first victory obtained was a variety in which the 

 distinct lines on the base of the lower petals had 

 broken into a decided blotch. For garden decoration 

 the size and intensity of colour infused into the 

 small, pale blue, Pyrenean V. cornuta, is simply 

 marvellous, but not more so than that of many of 

 the huge modern representatives of V. tricolor, 

 several times the size of the original. 



The unnatural conditions brought about by culti- 

 vation and artificial intercrossing are well illustrated 

 in Primula Sinensis, the garden forms of which are 

 rapidly becoming self-fertile, by fertilising varieties 

 with their own pollen in order to perpetuate the 

 colours. Naturally, this species, like most of the 

 genus, is dimorphic ; that is, one individual has 

 a short style, with stamens seated at the mouth of 

 the corolla ; while another has a long style, w T ith the 

 stamens inserted low down the tube of the corolla. 

 The forms are about equally distributed, and the 

 most legitimate union is formed by fertilising the 

 long-styled form with pollen from the stamens 

 seated at the mouth of the corolla, and vice versa. 

 By so doing, a progeny with a stronger constitution, 

 and more prolific in seeds, is the result. The object 

 of the florist, however, in labouring to produce 

 flowers up to his ideal standard, has a tendency to 

 obliterate many natural habits, however constant in 

 a state of nature. 



All the European varieties of cultivated Grapes 

 have been obtained from Vitis vinifera, of which 

 there are several more or less distinct varieties in a 

 wild state. It has been crossed, however, with the 

 American V. labrusca, but that does not concern us 

 at present. In order to obtain new sorts, owing to 

 the special adaptation for self -fertilisation in the 

 Vine, and the prepotency of the pollen of a variety 

 in preference to that from another, it is necessary to 

 take great precautions in order to insure that cross- 

 fertilisation shall take effect between two varieties 

 artificially impregnated. This does not imply that 



varieties do not vary (although they are pretty 

 constant) unless carefully and artificially crossed, for 

 we have an instance on record that a golden-coloured 

 variety has been raised in England from a black one 

 which had no chance of being cross-fertilised, and 

 Van Mons of Belgium raised a multitude of varieties 

 from one Vine, presenting great variation. The 

 flowers to be fertilised should be covered some days 

 previous to their expansion with a muslin bag, 

 to prevent the access of insects or foreign pollen, 

 and operated on in the manner previously detailed 

 All this should be accomplished in the early part of 

 the day, while the sun is shining. As in the case of 

 many other fruits or flowers, the most valuable sorts 

 have been obtained by successively interbreeding 

 the progeny of the first results. 



Amongst Apples and Pears it may seem impossible 

 to obtain anything more distinct from the many 

 excellent varieties under cultivation ; but much may 

 vet be done in raising varieties better able to endure 

 spring frosts. Artificial cross-fertilisation, if con- 

 ducted with scientific accuracy, can effect great 

 achievements. Instead of leaving it to the chance 

 work of insects and other natural agencies, the 

 hybridist, having certain ends in view, will select 

 parent plants possessing the desired properties, by 

 the union of which he expects to attain his object. 

 The flowers produce honey, which, in conjunction 

 with the showy wide-open petals, offers great attrac- 

 tions to bees and other insect visitors. Therefore 

 the flowers to be cross-fertilised should be properly 

 protected from the introduction of other pollen, by 

 whatever agency, in order to insure the accuracy 

 of the experiment. Their own stamens should be 

 removed before the pollen is shed, lest the pistil 

 should exhibit an elective affinity for its own in 

 preference to foreign j)ollen. 



What applies to Apples and Pears will answer 

 equally well with regard to Peaches, Nectarines, 

 Apricots, Plums, and Cherries, popularly known as 

 stone-fruits. 



Lath yr as odoratus, the Sweet Pea, and Pimm 

 sativum, are two remarkable instances of plants be- 

 longing to the Leguminosee, with showy flowers, well 

 adapted for cross-fertilisation, but which are, never- 

 theless, almost invariably self-fertilising in a state of 

 cultivation. Both are exotic plants, and very little 

 frequented by insects in this country, the common 

 honey-bee being, however, partial to the first, a very 

 important fact for the seed- growers, who can culti- 

 vate the varieties in close proximity to one another 

 without danger of intercrossing. In proof of this, 

 varieties of the Garden Pea, raised by Mr. Andrew 

 Knight, from cross-fertilised sorts, and cultivated 

 for sixty years, retained a vigorous constitution, and 

 reproduced themselves true to name. Furthermore, 



