184 



SCIENCE OF GARDENING. 



Part II. 



but rather in the quality, as ft is not always plants having the most pollen that produce the most seeds. The 

 two stamens of the orcnidse fecundate 8000 seeds, and the five stamens of tobacco fecundate 900: while the 

 50 stamens of barringtonia, the 250 of thea, and the 80 of the caryophilli, fecundate only two or three 

 ovaries. 



Sect. IX. The Propagation of the Species. 



828. As the life of the vegetable, like that of the animal, is limited to a definite period, 

 and as a continued supply of vegetables is always wanted for the support of animals, 

 what we call art, or nature operating by means of the animal man, has taken care to 

 institute such means as shall secure the multiplying and perpetuating of the species in 

 all possible cases. 



829. Equivocal Generation. It was long a vulgar error, countenanced even by the philosophy of the times 

 that vegetables do often spring up from the accidental mixture of putrid water and earth, or other putrid 

 substances, in the manner of what was called the equivocal generation of animals ; or at the very least, 

 that the earth contains the principle of vegetable life in itself, which in order to deveiope, it is only neces- 

 sary to expose to the action of the air. The former alternative of the error has been long ago refuted ; 

 the latter has lost its hold, having been also refuted by Malpighi, who proved that the earth produces 

 no plant without the intervention of a seed, or of some other species of vegetable germ deposited in it by 

 nature or by art. 



830. Propagation by seeds. When the seed has reached maturity in the due and 

 regular course of the developement of its several parts, it detaches itself sooner or later 

 from the parent plant, either singly or along with its pericarp, and drops into the soil, 

 where it again germinates and takes root, and springs up into a new individual. Such 

 is the grand means instituted by nature for the replenishing and perpetuating of the 

 vegetable kingdom. 



831. Dispersion of seed. If seeds were to fall into the soil merely by dropping down from the plant, 

 then the great mass of them, instead of germinating and springing up into distinct plants, would grow up 

 only to putrefy and decay ; to prevent which consequence 



nature has adopted a variety of the most efficacious contri- 

 vances, all tending to the dispersion of the see<L The first 

 means to be mentioned, is that of the elasticity of the peri- 

 carp of many fruits, by which it opens when ripe, with a sort 

 of sudden spring, ejecting the seed with violence, and throw- 

 ing it some considerable distance from the plant. This may be 

 exemplified in a variety of cases ; the seeds of oats when ripe 

 are projected from the calyx with such violence, that in a fine 

 and dry day you may even hear them thrown out with a 

 slight and sudden snap in passing through a field that is ripe. 

 The pericarp of the Dorsiferous Ferns {Jig. 64 a) is furnished 

 with a sort of peculiar elastic ring (b), intended, as it would 

 appear, for the very purpose of projecting the seeds. The 

 capsules of the cucumber, geranium geum, and fraxinella, 

 discharge their seeds also when ripe with an elastic jerk. But 

 the pericarp of impatiens, which consists of one cell with 

 five valves, exhibits perhaps one of the best examples of this 

 mode of dispersion. If it is accidentally touched when ripe 

 it will immediately burst open, while the valves, coiling 

 themselves up in a spiral form, and springing from the stem, 

 discharge the contained seeds and scatter them all around. 

 The bursting of the pericarp of some species of pines is also 

 worthy of notice- The pericarp, which is a cone, remains 

 on the tree till the summer succeeding that on which it was 



produced, the scales being still closed. But when the hot ^^Jlfesfe^S"^ ^tsm* 5 



weather has commenced and continued for some time, so as *s^^f^^a^sr i <^ 



to dry the cone thoroughly, the scales open of their own 

 accord with a sudden jerk, ejecting the contained seeds : and if a number of them happen to burst together, 

 which is often the case, the noise is such as to be heard at some considerable distance. The twisted awn of 

 avena fatua {fig.65.), orwild oat, as well as that of geranium cicutarium, and some others, seems to have 

 been intended particularly for the purpose of aiding the further dispersion of the seed, after being discharged 

 from the plant or pericarp. This spiral awn or spring, , 

 which is beset with a multitude of fine and minute hairs, 

 possesses the property of contracting by means of drought, 

 and of expanding by means of moisture. Hence it remains 

 of necessity in a perpetual state of contraction or dilatation, 

 dependent upon change of weather ; from which, as well as 

 from the additional aid of the fine hairs,which act as so many 

 fulcra, and cling to whatever object they meet, the seed to 

 which it is attached is kept in continual motion till it either 

 germinates or is destroyed. The awn of barley, which is 

 beset with a multitude of little teeth all pointing to its 

 upper extremity, presents also similar phenomena. For 

 when the seed with its awn falls from the ear and lies flat 

 upon the ground, it is necessarily extended in its dimensions 

 by the moisture of the night, and contracted by the drought 

 of the day. But as the teeth prevent it from receding in 

 the direction of the point, it is consequently made to ad- 

 vance in the direction of the base of the seed, which is thus 

 often carried to the distance of many feet from the stalk on 

 which it grew. If any one is yet sceptical with regard to 

 the travelling capacity of the awn, let him only introduce 

 an awn of barley with the seed uppermost between his coat 

 and shirtsleeve at the wrist, when he walks out in the morn- 

 ing, and by the time he returns to breakfast, if he has 

 walked to any great distance, he will find it up at his arm- 

 pit. This journey has been effected by means of the con- 

 tinued motion of the arm, and consequently of the teeth of 

 the awn acting as feet to carry it forward. 



832. Where distance of dispersion is required, nature is 



