84 MORPHOLOGY, OR COMPARATIVE ANATOMY. 



as has been said, alternately, now on this side, now on that. This main 

 rachis is therefore not formed by one continuously growing shoot, but by 

 a succession of shoots of different generations placed one over the other 

 in definite order, thus forming a sympode (see ante, p. 39). In this manner 

 we may have spicate or racemose sympodial cymes closely resembling, on 

 a superficial inspection, spikes or racemes. If the bracts are present the 

 true nature of the inflorescence is apparent, because in that case the pe- 

 duncles are on the opposite side of the axis to the bracts, as \nHelianthemiim. 

 It often happens, however, in these cases that the bracts are wholly 

 wanting, as in Boraginaceae, in which the scorpioid cyme has been attri- 

 buted to repeated forking of the growing point ; but the sympodial theory 

 is the more probable. 



Forms of Cymes. The form of the cyme is sometimes further 

 indicated by such terms as a globose cyme, a linear cyme, and 

 so on. When the flowers are nearly sessile, forming a dense flat- 

 topped bunch, such as we see in the Sweet- William and other 

 species of Dianthus, the term fasciculus is sometimes used. Where 

 a cymose tuft of only a few flowers, crowded together in this way, 

 occurs in the axil of an ordinary leaf, the inflorescence is sometimes 

 called a ylomerulus, as in many of the Labiatse. 



Compound Inflorescence. Some plants, especially herbaceous 

 perennials, have compound inflorescence, wherein the flowering region 

 of the stem appears to be composed of a number of distinct inflores- 

 cences arranged on a regular plan. The plan of the ramification of 

 the main axis mav be the same as that of the individual inflorescence, 

 as in the Umbelliferse, where both the primary and the secondary 

 umbels unfold centripetally ; sometimes the separate inflorescences 

 are arranged in a different form belonging to the same class, as in 

 the case of the umbellate collection of spikes in certain Grasses 

 (Digitaria, fig. 149), &c. 



Mixed Inflorescence. In other cases there is a mixed condition, 

 since in many Composite the individual capitula are centripetally 

 developed, while they succeed one another on the main stem in a 

 centrifugal or cymose order ; in the Labiate the cymose axillary 

 glornerules (which, occurring opposite to each other, form verticil- 

 lasters or false whorls) are developed from below upwards, the main 

 stem being indefinite, and they are often crowded together above 

 so as to form a kind of compound spike. 



The general facts of the morphology of the different forms of inflo- 

 rescence are thus seen to be conformable to the laws ruling the develop- 

 ment and ramification of the stem, as already explained. 



The different modes of inflorescences often pass one into the other, and 

 .such inflorescence as scorpioid cymes may originate either in the manner 

 above described, or, very rarely, by direct forking of the growing point 

 [Warming]. The difference between a dichotomy of the growing point 



