612 



BOTANY 



alternate, pinnate leaves. 



Flowers usually actinomorphic, tetramerous or penta- 

 merotis with a large iutrastaminal 

 disc. Oil-containing cavitii- in 

 all the members. 



I M l'i 1 11 1A NT ( i KN KUA. Rlltd 



graveolcns (Fig. 650), the Rue, is 

 a somewhat shrubby plant with 

 pinnately divided leaves. The 

 terminal flowers of the dichasial 

 inflorescences are pentamerous in 

 robust examples ; all the other 

 flowers are tetramerous. Dictam- 

 nus Fraxinella has panicles of 

 conspicuous, dorsiventral flowers ; 

 the carpels are free in their upprr 

 portions. The important genus 

 Citrus ( 29 ) has peculiarly con - 

 structed flowers (Figs. 651, 652). 

 The numerous stamens are uiiitnl 

 in bundles and arranged in a 



nat. size). 



Fio. 651. Floral diagram of.Ci<) i 

 vulgarif. (After EKHI.EB.) 



single whorl. The number of 

 carpels is also increased. The 

 fruit is a berry ; the succul- 

 ent portion is formed of large 

 cells with abundant cell-sap 

 which project into and fill 

 up the loculi of the ovary. 

 The leaves of many species 

 are simple and provided with 

 more or less winged petioles. 

 Other species have trifoliate 

 leaves and the articulation at 

 the base of the lamina shows 

 that the apparently simple 

 leaves correspond to impaii- 

 pinnate leaves, of which only 

 the terminal leaflet is devel- 

 oped. The thorns at the base 

 of the leaf are derived by 

 modification of the first leaves 



Fio. 652. Citrus vulgaris (A nat. size). OFFICIAL. 



