738 THE FLORAL STEM. 



axes, and so on throughout the entire series. The unfolding of the flower-buds 

 therefoi-e proceeds always from the centre towards the circumference of the 

 inflorescence in accordance with the succession of age, and consequently such an 

 inflorescence may be termed centrifugal. The simplest form, the type of all 

 centrifugal inflorescences, is the simple cyme (cyma). This pi'csents only three 

 flower-stalks, a central older one (the raeliis) and two younger lateral ones. Since 

 the latter spring at the same level from the rachis, the simple cyme has the 

 appearance of a three-pronged fork. It often happens that the flower-bud on 

 the rachis becomes stunted or does not develop at all, and then the inflorescence 

 looks like a two-pronged fork (e.g. in many species of Lonicera). If the lateral 

 axes arising from the rachis serve as starting-points for secondary lateral axes, and 

 if the ari'angement just described is repeated in them, a compound cyme (cymM 

 composita) results. The flower-stalks may be arranged either as two prongs or 

 three prongs in the compound cyme, and this branching may be repeated almost 

 indefinitely, as is the case, for example, in Gypsophila paniculata. When one 

 of the opposite flower-stalks, or lateral axes of a cyme, does not develop, while 

 the other, on the contrary, becomes very vigorous and projects beyond the rachis, 

 this lateral looks like the main axis, and at first siglit the rachis is mistaken 

 for a lateral shoot. Similarly on this vigorous lateral axis, one of the secondary 

 lateral shoots does not develop, while the other continues to grow the more 

 strongly. If this happens continuously, the form of cymose inflorescence called 

 scorpioid (cincinnus) is formed, numerous modifications of which have been 

 distinguished. If the flower-stalks of a compound cyme are all plainly visible 

 and the whole inflorescence bulky and diftuse, it is termed a panicle (pavicula): 

 if the flower-stalks are much shortened and the flowers consequently crowded 

 thickly together, the inflorescence is called a fascicle {fasciculus). Caryophyl- 

 lacese, Labiateis, and Boraginese exhibit an almost inexhaustible variety of cymose 

 inflorescences. 



Centripetal inflorescences may be recognized by the fact that the rachis 

 terminates in a bud which is the youngest structure of the whole inflorescence, 

 the flower-stalks which spring from the base of the rachis being the oldest 

 lateral axes. Looking down from above on such an inflorescence, or observing 

 the points of insertion of the individual flower-stalks in horizontal projection, the 

 lowest, and at the same time the oldest flower-stalks, are seen to stand at the 

 periphery, the youngest at the centre of the inflorescence. The flowers on the 

 oldest flower-stalks unfold first, those of the youngest last; the blossoming 

 therefore proceeds in a centripetal direction. The rachis is terminated as a rule 

 by a stunted bud which does not complete its development; occasionally, however, 

 this bud does develop; it assumes the form of a foliage-bud from which later on 

 is formed a leafy shoot, as can be seen especially in several Australian Myrtales 

 from the section of the Leptospermea? {Callistemon, Metrosideros, Melaleuca), and 

 also in many Bromeliacese (e.g. the Pine-apple, Ananassa sativa). Among centri- 

 petal inflorescences may be distinguished the raceme (raccmus) with elongated 



