SYSTEMS OF BOTANICAL CLASSIFICATION. 



183 



By a natural order or family of plants must 

 therefore be meant a series or assemblage of 

 genera, which all present the same characters in 

 thfe organs of fructification. 



Thus the family of cruciferae is characterized 

 by a dicotyledonous embryo, a siliquose or sili- 

 culose fi-uit, usually four petals opposed to each 

 other in pairs, stamina in determinate number, 

 &c. AU the genera of that family must present 

 the same characters, but only with some slight 

 modifications, which do not alter the primitive 

 type, but afford distinctive characters for the 

 genera which collectively constitute the family 

 in question. 



By following a course like this, botanists have 

 brought togetlier the various species of plants, 

 so as to form them into groups or natural fami- 

 lies. But as these families are numerous, it was 

 necessary to distribute them into classes, in which 

 regard should be had to the same resemblance 

 and affinity. It is to this classification of the 

 families that the name of Jussieu's Method, or 

 the system of natural families, has been given. 

 This system has been divided into fifteen 

 classes. The primary divisions are derived from 

 the characters which may be obtained from the 

 presence or absence of the embryo ; whence the 

 cinbryonate and inemhryonate plants. 



The embryonate plants are distinguished ac- 

 cording to the number of their cotyledons : 1st, 

 Into monocotyledonous ; 2dly, Into dicotyledo- 

 nous. AU vegetables are arranged under these 

 three primary divisions : acotyledones, iiionocoty- 

 Icdones, dicotyledones. 



The second consideration, or that by which 

 the classes properly so called are established, is. 

 founded upon the relative insertion of the sta- 

 mina, or of the staminiferous monopetalous co- 

 rolla. Now, we have seen that there are three 

 kinds of insertion : 



1. The Jiypogynous insertion, or that in which 

 the ovary being entirely free, the stamina or the 

 staminiferous coroUa are inserted close around 

 its base. 



2. The perigynous insertion, or that in which 

 the ovary being free or parietal, the stamina or 

 the staminiferous monopetalous corolla are in- 

 serted into the calyx at a certain distance from 

 the circumference of the base of the ovary. 



3. The epigynows insertion, or that in which 

 the ovary is always inferior, and in which the 

 stamina or the staminiferous corolla are inserted 

 upon the upper part of the ovary. 



These three kinds of insertion serve to estab- 

 lish an equal number of classes. 



The acotyledones being destitute of embryos, 

 and consequently of flowers and fruits, could not 

 be brought under this division, but constitute 

 the first class. 



The monocotyledones, possessing these three 

 modes of insertion, have been divided into three 



classes: 1. Monocotyledones, with hypogynous 

 stamina ; %. Monocotyledones, with perigynous 

 stamina; 3. Monocotyledones, with epigynous 

 stamina. 



The acotyledones and monocotyledones, there- 

 fore, form four classes, thus : " 



Acotyledones, . . • . . Class I. 



/■stamina hypogynous, Class II. 



Monocotyledones, J stamina perigynous. Class III. 



(^stamina epigynous. Class IV. 



The dicotyledones being much more numer- 

 ous than the acotyledones and monocotyledones 

 together, it was necessary to increase the num- 

 ber of their divisions. Here the insertion, al- 

 though still attended to, becomes, a secondary 

 character. Thus it has been observed, that these 

 plants are destitute of a corolla or are apetalous, 

 or that they have a staminiferous monopetalous 

 coroUa, or that their coroUa is polypetalous. 

 These distinctions have given rise to the three 

 first divisions that have been established among 

 the dicotyledones, namely : 



1. Apetalous dicotyledones. 



2. Monopetalous dicotyledones. 



3. Polypetalous dicotyledones. 



The insertion has been employed as a second- 

 ary character for subdividing these three sections 

 into classes. Thus the apetalae form three classes, 

 in which the insertion is epigynous, perigynous, 

 and hypogynous. 



The monopetalse, of which the corolla always 

 bears the stamina, in like manner form three 

 classes, according as their staminiferous corolla 

 is hypogynous, perigynous, or epigynous. The 

 last, or epigynous class of the monopetalse, has 

 been further subdivided, according as the stamina 

 are free or connected by their anthers, which 

 carries the number of classes in the monopetalous 

 corollas to four, namely : 



/staimjia hypog'ynoiis, 

 stamina perigynous. 



Class I. 



Class II. 



] . . "1 anthers united, Class III. 



(.stamina epigynous ) ^^^^^ j^^^^ ^^^ ,y_ 



These four classes, together with the three 

 classes of the apetalous dicotyledones, and the 

 four classes of the monocotyledones and acotyle- 

 dones, form eleven. 



The polypetalae have, in like manner, been di- 

 vided into three classes, according to their mode 

 of insertion, which is epigynous, perigynous, or 

 hypogynous. 



Lastly, in the fifteenth or last class, are placed 

 all the dicotyledonous plants, whose flowers are 

 essentially unisexual, and separated upon distinct 

 individuals. They have been named irregular 

 diclinous plants. 



Such are the fifteen classes which M. Jussieu 

 established in the vegetable kingdom, for the 

 purpose of methodically arranging the different 



