12 



HISTORY OK THE VEGETABLE KINGDOM. 



ou plants is called pubescence, mid will be more 

 particulai'ly alluded to afterwards. 



CHAP. IV. 



THB ORGANS AXD FUNCTIOKS OF PLANTS. 



liN the foregoing pages we have treated of tlie 

 general sti-ucture of vegetables ; we now proceed 

 to consider the several pai-ts, or organs, of which 

 a plant is composed. A perfect plant consists 

 of a root, stem, and branches ; leaves, blossoms, 

 with the parts of fiiictification, seeds, and, 

 lastly, fruit. The root, stem, and leaves, as 

 conducing to the nutrition and growth of the 

 plant, are called the conservative or nutritive 

 organs. The flowers, with the pai-ts of fructifi- 

 cation, as contributing to the multiplication of 

 the species, are termed the reproductive organs.* 

 As there is a gradation, however, in the vegeta- 

 ble kingdom, many plants have not all the organs 

 now enumerated. Some have neither leaves nor 

 stem, others are destitute of flowere, or even seeds, 

 and propagate their kinds by a simple sponile, 

 which partakes as much of the nature of a bud 

 or incipient germ, as a regular seed. Before pro- 

 ceeding to describe the organs in detail, we shall 

 give a short, general view of the different parts 

 of plants. 



The firet, or most perfect division of plants, 

 is called Phanerogamic, or those having con- 

 spicuous blossoms. A plant of this class con- 

 sists of, 1st, The root, or that part of the lovi-er 

 extremity of the plant which enters the earth, 

 where it sends out filaments and fixes the plant 

 in the soil, or, in a few aquatic plants, floats 

 loose in the water. The use of the roots is to 

 absorb the nutritive juices from the soil. 2d, 

 'J'he stem, which grows upwards into the atmos- 

 jihere, and sends out branches, to which the leaves 

 are attached. The stem contains the cells and 

 sap vessels already described ; it is covered with 

 the bark, and gives strength and solidity to the 

 plant. Sd, The leaves are those green mem- 

 branous appendages attached to the branches of 



* Linntpus distiibiitos tlie parts into root, herb, and 

 fractiflcation ; the herb comprelienjin/ the tnmk, 

 brandies, and loaves. This is perliaps sufficiently cor- 

 rect, considered as a division ; but is objectionable \vitli 

 regard to the use of one of the terms employed. For 

 as the term hcrli was previously appropriated to the 

 designation of a peculiar class, or division of plants, 

 It ought not to have been employed to signify also a 

 part of the plant itself. Another division is that by 

 which the parts in question are distributed into i>er- 

 tnanent, and temporary, or deciduous — the permanent 

 parts being the root, stem, and branches, which con- 

 tinue to exist as long as the plant vegetates, and the 

 temporary parts being the leaves, llower, and fruit, 

 which fall off and are renewed annually, at least in 

 those that are th:msclvcs perennial.- Krilh't Bolani/. 



the stem, or thoy grow out immediately from 

 the root in those plants having no middle stem. 

 Their office is to absorb the gases of the atmos- 

 phere, which combine with the juices of the 

 plant. 4th, The flowere or blossoms, containing 

 the parts of fructification, to which are attached 

 the fruit and receptacles of the seed. The flower 

 consists of the calj/x or cup attached to the flower 

 stalk, on which is fixed the corolla or coloured 

 portion of the flower, which may be either fonned 

 I of one continuous piece, like a cup or bell, or oi 

 I several pieces called petals. The parts of iruc- 

 I tification consist of the stamens or male organs, 

 i with the anthers, filled with pollen or fecundat- 

 ing dust ; and the pistil or female organ, occu- 

 pying the centre of the flower, and terminating 

 in an ovmy or receptacle for the seeds. 6th, The 

 pericarp, of very variable fomi and consistence, 

 is the ovary or seed bag fully developed, and 

 contains the ovules, which are in process of time 

 I matured into seeds. Gtli, The seeds contained 

 in the pericarp, are attached to it by a filament, 

 called the placenta. They have an external skin 

 or covering, and a kernel; within this is attached 

 the embryo or germ of the future plant, and 

 either one or two lobes or cotyledons, destined 

 to afford the first nourishment to the germ. 

 From the nature of the cotyledons, plants are 

 divided into two great and distinctive classes : 

 Monocotyledonous with one seed lobe, Dieotylc- 

 daiious with two seed lobes. Of the former 

 class are grasses, palms, lilies ; to the latter 

 belong the oak, elm, pea, carrot, and numerous 

 other families. The acotyledonous class, again, 

 includes those plants which have no seed lobe, 

 and either no fructifj'ing organs, or very imper- 

 fect ones. 



But even among the first or highest class of 

 plants, all the organs are not uniformly present. 

 Thus neither the plantain, nor the common prim- 

 rose, have any stem or stalk ; there are no leaves 

 in the dodder. In monocotyledonous plants 

 there is no corolla or flower blossom around the 

 parts of fructification, but only a simple integ- 

 ument ; even this integument is in the willow 

 awanting. Sometimes the blossom contains only 

 one of the several organs, as in the hazel, where 

 the stamens are found in one flower, and the 

 pistils in the other, or both sexual organs disap- 

 pear altogether,as in the viI)unium,portencia, &c. 

 Yet, in all those different exceptions, this al)- 

 sence of organs is only accidental, and has no 

 marked influence on the rest of the organization ; 

 for it will be found that plants which want 

 those organs, do not deviate essentially either in 

 their external characters, or in their mode of 

 vegetation and reproduction from those which 

 possess them. 



The second great division of the vegetable 

 kingdom is into cryptogamic or acotyledonous 

 pliints. Liiinicusgave thorn the name of ciypto- 



