382 London Horticultural Society and Garden.- 



more or less essential to the process of vegetation. Roots are of various 

 kinds and shapes ; but their use is always the same, viz. to extract mois- 

 ture from the ground, and to serve as a channel for conveying it to other 

 parts of the plant, where it is afterwards converted into sap. Roots, properly 

 so called, can seldom be propagated by division ; and when bulbs produce 

 offsets, each is complete in itself, and not a part of the old root. The mere 

 circumstance of part of a plant being buried in the earth does not make it 

 a root. The tubers of potatoes, for example, partake more of the nature 

 of branches than roots, producing buds or eyes, each of which is capable 

 of forming a perfect plant ; and bearing to be divided without destroying 

 the vital principle, which ordinary roots will not. Stems or trunks are 

 highly important, both as being the channels to convey nourishment to the 

 leaves, flowers, and fruit, and as being, in trees, the part convertible into 

 timber for the purposes of profit. Leaf-buds (so called to distinguish 

 them from flower-buds) in trees are, in fact, trees in embryo, and afford 

 the only certain means of multiplying varieties. The brown scales that 

 envelope these buds, when they first burst from the tree, are diminished 

 and imperfect leaves of the preceding season's formation, and generally 

 drop off as soon as the inner leaves expand. Leaves may be called the 

 lungs of plants, as through them the sap is exposed to the influence of the 

 atmospheric air. They are furnished with pores, which can imbibe nourish- 

 ment as well as throw off superfluous moisture. Petals are coloured 

 leaves, useful for protecting the parts necessary for the fructification of 

 seed. There is no essential difference, in the eye of the botanist, between 

 the calyx and the corolla. Every flower is provided with one or more 

 threads or filaments, called stamens; each of which is loaded with a case, 

 or anther, containing a kind of dust called the pollen. This powder, which 

 is necessary to the fecundation of seeds, is conveyed to the seed-vessel 

 (a thick cell or protuberance containing the seed, and growing in the centre 

 of the flower) by means of a tube-shaped body that usually surrounds it, 

 called the style; the stigma or head of which is the only part about the 

 whole plant which is not covered with a membrane, and which, conse- 

 quently, admits the free passage of the pollen. Plants having only stamens 

 are called males, and those having only styles female; while the majo- 

 rity of plants, possessing both, are called bisexual. This system was deve- 

 loped by Linnaeus. Varieties of plants cannot be propagated unvaryingly 

 by seed ; as every plant thus raised is a distinct individual, often differing 

 considerably from the parent plant. Double-blossomed plants very seldom 

 bear seed ; and Mr. Lindley mentioned the double-blossomed cherry, as an 

 instance of a plant which could only be propagated by cuttings. Some 

 exceptions, however, occur to this rule. Mr. Lindley concluded his ob- 

 servations on the sexes of plants by quoting some verses from Dr. Darwin. 

 The sap is the nourishment of plants. Various theories have been broached 

 respecting its circulation, which Mr. Lindley promised to explain in a future 

 lecture. It is formed from aqueous particles imbibed by the root, and 

 forced up the stem to the leaves ; where it acquires an additional portion 

 of oxygen from the atmospheric air, and returns to the root, imparting 

 nourishment to all the different parts of the tree in its progress. It rises 

 in the spring, and sinks in the winter : during this season, plants are gene- 

 rally in a dormant state. Contrary to what might be expected, the sap 

 appears first in motion at the extremity of the branch. Air, light, and 

 heat are indispensable to plants ; and, according as one or more of these 

 important agents are deficient, the plant is imperfect. If there were not 

 enough light, the plant would not attain its proper colour ; and without 

 a due proportion of air and warmth, fruit would be deficient both in 

 flavour and appearance. In conclusion, Mr. Lindley quoted a passage from 

 " an elegant and enlightened author," remarking on the constant change 

 which pervades all nature; and that all things after death sink into cor- 

 ruption, only to rise again in new forms of beauty and vigour, — J. W. h- 



