DeCandolle's Vegetable OrganograpJiy. 16SL 



Primordial Leaves. The following bear simply the name of Leaves. Those 

 which immediately surround the flower receive the name of Bracts, and the 

 flower itself is composed of several verticils of appendicular organs, much 

 modified. 



*' 18th, The appendicular organs perform, according to their position and 

 mode of developement, several different functions, of which the principal 

 are : — 



" 1st, That of nourishing organs, as the cotyledons and leaves; 



" 2d, That of protecting organs, as the scales of buds, bracts, sepals, petals, 

 carpels in their last stage ; 



" 3d, That of fructifying organs, as the stamens, and the carpels, during the 

 first stage of their existence. Several partake of both of these functions. 



" 19th. The nourishing appendicular organs are, at their origin, alternate in 

 endogenous plants, called also, for this reason, Monocotyledons ; opposite or 

 verticillate in Exogens, called also Dicotyledons. In the course of their 

 developement, those of Endogens always remain alternate or spiral, those of 

 Exogens may either remain in their primitive state, or take a spiral disposition. 



" 20th. The appendicular organs which compose the flowers are, in both 

 classes, disposed in concentric verticils ; the innermost are sometimes spiral. 



" 21st. The protecting appendicular organs hold a middle station, in form, 

 size, colour, and often also in position, between the two other classes ; and 

 we frequently see them metamorphosed, either into organs decidedly nourish- 

 ing, or more rarely into fructifying ones. 



" 22d. The appendicular organs are generally composed of a petiole and 

 limb, but one of them may be wanting. The Petiole, which is the bundle of 

 fibres not as yet disunited, has its fibres longitudinal ; the Limb, which is the 

 part formed by the expansion of the fibres, has them more or less diverging. 

 These fibres of the limb, or Nerves of leaves, are generally curved in Endogens, 

 and separate at angles more or less acute in Exogens. 



" 23d. The nerves of curvi-nerved leaves converge towards the apex, or 

 diverge from a middle bundle. Those of anguli-nerved ones are pinnate, pal- 

 mate, or pedate ; but the portions of the limb of the three last classes are 

 penni-nerved, so that this form seems essential to the leaves of Dicotyledons. 



" 24th. The leaves of Dicotyledons are the only ones which have been 

 seen, either composed of joints or leaflets, or furnished with lateral stipules. 



" 25th. Germs, or the undeveloped rudiments of new individuals, appear 

 able to arise from all parts of the surface ; but there are certain points where 

 they are developed in preference, such as the axils of the appendicular organs, 

 and I he extremities of the fibres of their limbs, 



" 26th, The germs which are placed in the axils of the appendiculur organs, 

 along the stem or petiole, may be developed by the action of the nutritive 

 forces alone. Those which are situated at the extremity of the lateral fibres 

 of the limb, almost always require (except in Briophyllum), in order to be 

 developed, a particular operation called Fecundation, 



" 27th, The germs w^hich are developed without fecundation most fre- 

 quently arise united to the mother plant without having proper envelopes, and 

 without shooting out roots : they then form branches. Some separate when 

 they are furnished with a tubercule or store of nutriment : they then form 

 separate individuals, and produce roots. 



" 28th. Every stem or branch can shoot out adventitious roots. In Dico- 

 tyledonous trees, these spring from the lenticels ; every branch, furnished with 

 them, or capable of producing them, may easily be separated from the mother 

 plant, and form a distinct being. 



" 29th. The germs which are developed by fecundation are always con- 

 tained in a closed envelope, furnished with the rudiments of a root and appen- 

 dicular organs. They receive the name of Embryos, 



" 30th. The unfecundated germs perpetuate the varieties of the mother 

 plant ; the embryos only retain the characters of races or species. 

 ' "31st. The appendicular organs which immediately surround the flowers. 



