Book I. 



PROPAGATION OF VEGETABLES. 



185 



also furnished with a resource. One of the most common modes by which seeds are conveyed to a dis- 

 tance from their place of growth is that of the instrumentality of animals. Many seeds are thus carried to 

 a distance from their place of growth merely by their attaching th'emselves to the bodies of such animals 

 as may happen accidentally to come in contact with the plant in their search after food ; the hooks or hairs 

 ■with which one part or other of the fructification is often furnished serving as the medium of attachment, 

 -Jid the seed being thus carried about with the animal till it is again detached by some accidental cause, and 

 *t' last committed to the soil. This may be exemplified in the case of the bidens and myosotis, in which 

 \he hooks or prickles are attached to the seed itself ; or in the case of galium aparine and others, in which 

 they are attached to the pericarp ; or in the case of the thistle and the burdock, in which they are attached 

 to the general calyx. Many seeds are dispersed by animals in consequence of their pericarps being used 

 as food. This is often the case with the seeds of the drupe, as cherries, sloes, and haws, which birds 

 often carry away till they meet with some convenient place for devouring the pulpy pericarp, and 

 then drop the stone into the soil. And so also fruit is dispersed that has been hoarded tor the winter, 

 though even with the view of feeding on the seed itself, as in the case of nuts hoarded up by squirrels, 

 which are often dispossessed by some other animal, that not caring for the hoard scatters and disperses it. 

 Sometimes the hoard is deposited in the ground itself, in which case part of it is generally, found to take 

 root and spring up into plants. Though it has been observed that the ground-squirrel often deprives the 

 kernel of its germ before it deposits the fruit it collects. Crows have been also observed to lay up acorns 

 and other seeds in the holes of fence-posts, which being either forgot or accidentally thrust out, fall ulti- 

 mately into the earth and germinate. But sometimes the seed is even taken into the stomach of the 

 animal, and afterwards deposited in the soil, having passed through it unhurt. This is often the case with 

 the seed of many species of berry, such as the mistletoe, which the thrush swallows and afterwards deposits 

 upon the boughs of such trees as it may happen to alight upon. The seeds of the loranthus americanus, 

 another parasitical plant, are said to be deposited in like manner on the branches of the coccoloba grandi- 

 flora, and other lofty trees ; as also the seeds of Phytolacca decandra, the berries of which are eaten by 

 the robin, thrush, and wild pigeon. And so also the seeds of currants or roans are sometimes deposited, 

 after having been swallowed by blackbirds or other birds, as may be seen by observing a currant-bush or 

 young roan-tree growing out of the cleft of another tree, where tlie seed has been left, and where there 

 may happen to have been a little dust collected by way of soil ; or where a natural graft may have been 

 effected by the insinuation of the radicle into some chink or cleft. It seems indeed surprising that any 

 seeds should be able to resist the heat and digestive action of the stomach of animals ; but it is undoubtedly 

 the fact. Some seeds seem even to require it. The seeds of magnolia glauca, which have been brought 

 to this country, are said to have generally refused to vegetate till after undergoing this process, and it is 

 known that some seeds will bear a still greater degree of heat without any injury. Spallanzani mentions 

 some seeds that germinated after having been boiled in water : and Uu Hamel gives an account of some 

 others that germinated even after having been exposed to a degree of heat measuring 235° of Fahrenheit. 

 In addition to the instrumentality of brute animals in the dispersion of the seed might be added also that 

 of man, who, for purposes of utility or of ornament, not only transfers to his native soil seeds indigenous to 

 the most distant regions, but sows and cultivates them with care. 



833. The agency of winds is one of the most effective modes of dispersion instituted by nature. Some seeds 

 are fitted for this mode of dispersion from their extreme minuteness, such as those of the mosses, lichens, 

 and fungi, which float invisibly on the air, and vegetate v;herever they happen to meet with a suitable 

 soil. Others are fitted for it by means of an attached wing, as in the case of the fir-tree and liriodendron 

 tulipifera, so that the seed, in falling from the cone or capsule, is immediately caught by the wind, 

 and carried to a distance. Others are peculiarly fitted for it by means of their being furnished with 

 an aigrette or down, as in the case of the dandelion, goat's-beard, and thistle, as well as most plants of the 

 class Syngenesia s the down of which is so large and light in proportion to the seed it supports, that it is 

 wafted on the most gentle breeze, and often seen floating through the atmosphere in great abundance at 

 the time the seed is ripe. Some have a tail, as in clematis vita alba. Others are fitted for this mode of 

 dispersion by means cf the structure of the pericarp, which is also wafted along with them, as in the case of 

 staphylea trifolia, the inflated capsule of which seems as if obviously intended thus to aid tlie dispersion 

 of the contained seed by its exposing to the wind a large and distended surface with but little weight. And 

 so also in the case of the maple, elm, and ash, the capsules of which are furnished, like some seeds, with 

 a membranous wing, which when they separate from the plant the wind immediately lays hold of and 

 drives before it. 



834. The instrumentality of streams, rivers, and currents of the ocean, is a further means adopted by 

 nature for the dispersion of the seeds of vegetables. The mountain-stream or torrent washes down to 

 the valley the seeds which may accidentally fall into it, or which it may happen to sweep from its banks when 

 it suddenly overflows them. The broad and majestic river, winding along the extensive plain, and tra- 

 versing the continents of the world, conveys to the distance of many hundreds of miles the seeds that may 

 have vegetated at its source. Thus the southern shores of the Baltic are visited by seeds which grew in 

 the interior of Gerjnany, and the western shores of the Atlantic by seeds that have been generated in the 

 interior of America. But fruits indigenous to America and the West Indies have sometimes been f ound 

 to be swept along by the currents of the ocean to the western shores of Europe. The fruit of mimosa scan- 

 dens, dolichos pruriens, guilandina bonduc, and anacardium occidentale, or cashew-nut, have been thus 

 known to be driven across the Atlantic to a distance of upwards of 2000 miles j and although the fruits 

 now adduced as examples are not such as could vegetate on the coast on which they were thrown, owing to 

 soil or climate, yet it is to be believed that fruits may have been often thus transported to climates or coun- 

 tries favorable to their vegetation. 



835. ProjMgation by gems. Though plants are for the most part propagated by means 

 of seeds, yet many of them are propagated also by means of gems ; that is, bulbs and buds. 



The caulinary bulb is often the means of the propagation of the species : it generally appears in the 

 axil of the leaves, as in dentaria bulbifera and lilium bulbiferum ; or between the spokes of their um- 

 bels, as in allium canadense ; in the midst of the spike of flowers, as in polygonum viviparum and poa 

 alpina. As plants of this last kind are mostly alpine, it has been thought to be an institution or re- 

 source of nature to secure the propagation of the species in situations where the seed may fail to ripen. 



836. The bud, though it does not spontaneously detach itself from the plant and form a new individual, 

 will yet sometimes strike root and develope its parts if carefully separated by art and planted in the 

 earth : but this is to be understood of the leaf-bud only, for the flower-bud, according to Mirbel, if so 

 treated, always perishes. 



837. Propagation by the leaves. The species may sometimes be propagated even by means of th > 

 leaves ; as in the aloe, sea-onion, and some species of arum, which if carefully deposited in the soil will 

 grow up into new plants, by virtue, no doubt, of some latent gem contained in them. The fungi and 

 lichens, according to Gasrtner, are all gemmiferous, having no sexual organs, and no pollen impregnat- 

 ing a germ. In the genus Lycoperdon, the gelatinous substance that pervades the cellular tissue is con- 

 verted into a proliferous powder ; in clavaria, the fluid contained in the cavities of the plant is converted 

 into a proliferous powder also ; and in the agarics, hypnum, and boletus, vesicles containing sobolifer- 

 ous granules are found within the lamina, pores, or tubes. Hedwig, on the contrary, ascribes to the 

 fungi a sexual apparatus, and maintains that the pollen is lodged in the volva. But here it is to be 

 recollected, as in the cases of the scutells of the lichens, that all fungi arc not furnished with a volva. 



