90 ORGANOGRAPHY. BOOK I. 



The scar formed by the separation of a leaf from its stem 

 is called the cicatricule. The withered remains of leaves, 

 which, not being articulated with the stem, cannot fall off, 

 but decay upon it, are called reliquice or induvice {debris, Fr.), 

 and the part so covered is said to be hviuviate. 



When leaves are placed in pairs on 

 opposite sides of a stem (^y.50.), and 

 on the same plane, they are called op- 

 posite: if more than two are opposite, 

 they then form what is called a whorl, 

 or verticillus : but if they arise at re- 

 irular distances from each other round 

 the stem, and not from the same plane, 

 they are then called alternate. 



In plants having Exogenous stems, 

 the first leaves, — namely, those which 

 are present in the embryo itself {cotyledons), — are uni- 

 formly opposite ; but those subsequently developed are either 

 opposite, verticillate, or alternate in different species : on the 

 contrary, in Endogens, the embryo leaf is either solitary, or, 

 if there are two, they are alternate : and those subsequently 

 developed are usually alternate also, but few cases occurring 

 in which they are opposite. 



Hence some have formed an opinion that the normal posi- 

 tion of the leaves of Exogens is opposite, or verticillate ; and 

 that when the leaves are alternate, this arises from the exten- 

 sion of a node; while that of Endogens is alternate, the whorls 

 beinff the result of the contraction of internodes. 



But it seeiBs more probable that the normal position of 

 all leaves is alternate, and their position upon the stem an 

 elongated spiral, as is in many cases exceedingly apparent, 

 as, for instance, in the genus Pinus, in Pandanus, which is 

 actually named Screw-pine, in consequence of the resem- 

 blance its shoots bear to a screw, and in the Pine apple ; the 

 Apple, the Pear, the Willow, the Oak, will also be found to 

 indicate the same arrangement, which is only less apparent 

 because of the distance between the leaves, and the irregu- 

 larity of their direction. If, in the Apple tree, for instance, a 

 line be drawn from the base of one leaf to the base of another, 



