98 



HISTORY OF THE VEGETABLE KINGDOM. 



Tlie fecundity of plants, in other words, tlie 

 astonishing numher of germs or seeds wliich they 

 produce, is one of the causes -vvhicli are most 

 powerful in facilitating their reproduction, and 

 in effecting their surprising multiplication. A 

 single capsule of the white poppy has been 

 known to contain 8000 seeds, and a single cap- 

 sule of the iianilla, from 10 to 1600 ; a single 

 stalk of zca mays will produce 2000 seeds; a 

 single plant of inule helenium, or elicampane, 

 3000; and a single spike of ti/pha major, or 

 gTeater cat's tail, 10,000 ; a single plant of tobacco 

 has been found, by calculation, to produce the 

 almost incredible number of 360,000; and a 

 single stalk of spleen- wort has been thought by 

 estimation to produce at least a million of seeds. 

 Let one imagine the regularly increasing pro- 

 gression of this number, merely to the tenth 

 generation of these plants, and he will hardly 

 conceive how the whole surface of the earth 

 should not be covered by them. But many 

 causes tend to nexitralize, in part, the effects of 

 this astonishing fecundity, which, by its very 

 excess, would soon prove injurious to the repro- 

 duction of phmts. In fact, all the seeds are not 

 placed by nature in circumstances favourable to 

 their development. Besides, numerous animals, 

 and man himself, deriving their principal nutri- 

 ment from fruits and seeds, destroy incalculable 

 quantities of them. Various circumstances fav- 

 our the natural dispersion of seeds. Some of 

 these result from the structure of the pericarp, 

 and others depend upon the seeds themselves. 

 Thus, there are pericai-ps which open naturally 

 with a kind of elasticity, by means of which the 

 seeds contained by them are projected to greater 

 or less distances. The fruits of hura crepitans, 

 dioncea musci2yuJ.a, the fraxinella, and balsamine, 

 separate their valves rapidly, and by a kind of 

 spring, -project their seeds by this means to 

 some distance. The fruit of ecballium elaterium, 

 when ripe, separates from the peduncle which 

 supported it, and projects its seeds with surpris- 

 ing rapidity through the cicatrix of its point of 

 attachment. 



The seeds of oats, when ripe, are projected from 

 the calyx with such violence, that in a fine and 

 dry day, in passing through a ripe field, they 

 may be heard as then thro^vn out with a sudden 

 snap. The pericarp of the dorsiferous ferus is 

 famished with a sort of peculiar elastic ring, in- 

 tended, as it would appear, for the very purpose 

 of projecting the seeds. The capsule of the 

 cucumber, geranium geiim, and fraxinella, dis- 

 charge their seeds also when ripe, with an elastic 

 jerk. But the pericarp of impatiens, which con- 

 sists of one cell, with five valves, exhibits, per- 

 haps, 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 con- 

 tained seeds, and scatter them all around. The 

 bursting of the pericarp of some species of pines 

 is also worthy of notice. The cone remains in 

 the tree till the summer succeeding that on 

 which it was produced, the scales being still 

 closed. But when the hot weather has com- 

 menced, and continued for some time, so as to 

 dry the cone thoroughly, the scales open of their 

 own accord with a sudden jerk, ejecting the con- 

 tained seeds, and if a number of them happens to 

 burst together, which is often the case, the noise 

 is such as to be heard at some considerable dis- 

 tance. The twisted arm of avena fatua, or wild 

 oat, as well as that particularly of geranium 

 cicutarizim, and some others, seems to have been 

 intended for the purpose of aiding the further 

 dispersion of the seed after being discharged from 

 the plant or pericarp. This spiral arm, or spring, 

 which is beset with a multitude of fine and 

 minute hairs, possesses the property of contract- 

 ing by means of drought, and of expanding by 

 means of moisture. Hence, it remains of neces- 

 sity in a perpetual state of contraction or dilata- 

 tion, 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 

 arm of barley, which is beset with a number of 

 minute teeth all pointing to its upper extremity, 

 presents also similar motions. For when the 

 seed with its arm 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 fi-om receding in the direc- 

 tion of the point, it is consequently made to 

 advance in the direction of the base of the seed, 

 which is thus often earned to the distance of 

 many feet from the stalk on which it grows. If 

 any one is sceptical with regard to this motion, 

 let him introduce an ear of barley with the seed 

 uppermost between his coat and shirt sleeve, at 

 the wrist, when he walks out in the morning, 

 and by the time he has returned, he will find it 

 has mounted to his arm pit. This journey has 

 been effected by means of the continued motion 

 of the arm, and consequently of the teeth of the 

 arm acting as feet to carry it forward. It is 

 obvious, however, that the modes of dispersion 

 now stated, can never carry the seed to any great 

 distance, but where distance of dispersion is re- 

 quired, nature is always furnished with a re- 

 source. One of the most common modes by 

 which seeds are conveyed to a distance from 

 their place of growth, is that of the instrumen- 

 tality of animals. Many seeds are thus trans- 

 ported merely by their attaching themselves to 

 the bodies of such animals as may happen 



