624 



FAKxMERS' REGISTER 



[No. 10 



From an inspection of ihe fbretroincj synopti- 

 cal viewoI'Linnieus'syslem orciassitication, it will 

 he seen that, the first eleven classes are charac- 

 terized b_v the number ol' tiie stamens, those sta- 

 mens beinj; tlisconnectpcl with each other, and 6l' 

 equal !en<i;th ; the two succeeding classes, viz. the 

 12ih and 13 derive their characters Irom the num- 

 ber and insertion of the stamens; the next two 

 classes, the 14th and loth are based upon the num- 

 ber and relative len;ith of the stamens ; the next 

 lour classes, the I61I1, I7th, 18th and 19lh upon 

 the connexion of the stamens with e;ich other; 

 the next class, viz. the 20th is founded on the ad- 

 hesion of the stamens to the pistil ; the iie.xt three 

 classes, the 21st, 22nd and 23rd are characterized 

 by the stamens and pistils frrowing in different 

 flowers, either upon the same or upon different 

 plants; and the remaining class, the 24ih, includes 

 all those plants whose flowers if they may be so 

 called, have no evident stamens and pistils; of this 

 character are the ferns, mosses, &c. In order to 

 determine the Litma'an class of any plant, all that 

 is ne(;essary is simply to examine its stamens in 

 the particulars referred to. The subdivision ol" 

 these classes into orders is generally based upon 

 some peculiarity in either the Btamens or the pis- 

 tils, characteristics taken from the stamens being 

 used where they are not necessary in determming 

 the class. There are however a few exceptions 

 to this general rule; viz. the orders of the 14th 

 class are based upon the presence or absence of 

 covering to the seed, those of the 15th class upon 

 the shape of the seed-pod, and those of the 24th 

 class are truly natural orders, and ought not to be 

 considered as properly parts of an artificial sys- 

 tem. 



" The object proposed by the natural system is 

 to bring together in groups those plants which 

 most resemble each other, not in a single charac- j 

 ter only, but in every essential point ; so that a 

 knowledge of any one individual of a group, will 

 give an adequate idea of the structure, habits, and 

 general properties of the whole. The subordinate 

 groups being combined into larger assemblages, and 

 these again into still more comprehensive divisions, 

 the whole vegetable kingdom is at length embraced 

 in the general classification. Thus, the genera are 

 groups of kindred species, the orders are assem- 

 blages of kindred genera, the classes and sub- 

 classes are still larger assemblages, embracing or- 

 ders, agreeing with each other in certain general 

 and important particulars." In arranging plants 

 according to such a system as this, it is necessary 

 to pass in review every separate origan, and not to 

 confine our attention to a single class of organs, 

 as in the case of the Linnroan system ; and besides 

 this, we must determine respecting the relative 

 value of the characters afforded by each class of 

 organs ; as a plant will be found to agree in some 

 of its characters with one family of plants, and in 

 others perhaps equally numerous, with an entire- 

 ly different family. It is from this last' mentioned 

 source that the principal difficulties arise in giving 

 to plants a natural arrangement. 



And here, it may be worth our while to devote 

 a little space to a brief examination of the relative 

 importance of the different characters afforded liy 

 t le different organs of plants, as it will give us, 

 not only a fuller insight into the nature of the na- 

 tiiral system, but also a bolter idea of what obser- 

 vation has taught the botanist, must be considered 



as permanent in the structure of a plant, and of 

 course in what particulars it will be impossible by 

 any artificial means to alter or improve it. And 

 here, i shall draw my information jirinciiially from 

 the chapter on classification in Gray's Elements of 

 Botany, a work to which f have frequently had 

 occasion to refer in tlie foregoing parts of' this 

 essay. 



Every organic peculiarity in which plants difler 

 or agree amonif themselves, is considered by the 

 botanist as a character. In determining respect- 

 ing the relative attention which should be paid to 

 each, their permanence is one of the first things 

 inquired into, those which are most permanent, 

 being of the highest value ; and those which are 

 most variable, of the lowest. Thus the seed-ves- 

 sel and the seed being produced year after year 

 without any perceptible variation except in size, 

 they furnish constant and permanent characters, 

 but the color of the ffowers, the surface of the 

 leaves whether smooth or hairy, the height of the 

 stem, &c., being liable to great changes, much 

 less dependence can be placed upon them as dis- 

 tinctive characters. The highest character pre- 

 sented by any organ is drawn from a consideration 

 of its presence or absence; thus the two great 

 classes of flowering and flowerless plants are dis- 

 tinguished by the presence or absence of flowers. 

 The characters next in importance are those fur- 

 nished by the position or arrangement of any class 

 of organs ; thus the two great groups into which 

 flowering plants are divided are distinguished by 

 the arrangement of the cellular and vascular tis- 

 sues ; the first [exogen^e] having the vascular tis- 

 sue arranged in concentric cylinders, around a 

 common axis, the pith ; and the second [endoge- 

 na?] having this tissue disposed in bundles and not 

 in cylinders. Characters drawn from the form, 

 connexion, relative lencrth and relative number of 

 organs, are next in importance, such as the num- 

 ber of stamens, pistils, seeds, &c. The abun- 

 dance of any tissue, intensity of color or odor, the 

 degree of pubescence, &c. are all characters of 

 the lowest rank, being of themselves insufficient 

 to distinguish species. 



The root furnishes fewer characters than any 

 other organ, the subterranean modifications of the 

 stem, such as bulks, tubers, &c. are of more im- 

 portance, but even as respects these, we often find 

 plants v/iiich should evidently belong to the same 

 natural tiimily differing from each other. 



The stem in its ordinary modifications, furnishes 

 numerous characters of great importance. Its 

 structure, whether exogenous or endogenous, dis- 

 tiniruis-hes the two sub-classes of fiowering plants 

 from each other, as has been already remarked. 

 The natural order of grasses are distinguished by 

 liaving cylindrical and hollow stems, closed at the 

 joints. Plants belonging to the natural order of 

 labiata;, which the garden sage (salvia officinalis) 

 may be mentioned as an example, have in almost 

 every instance square stems. All the plants of 

 Ihe Carolina allspice tribe (calycanthcce) have 

 stems with four imperfect centres of growth, on 

 the outside of the ordinary concentric circles of 

 wood. 



Leaves aflbnl a great variety oi characters of 

 difierent dcirrees ol' importance. The outline or 

 figure of leaves \a much more variable, and of 

 course, of much less inqjorlauce than their ar- 

 rangement on (he stem. All Labiate plants have 



