GROUP V. ANGIOSPERM.E. 439 



appears to be inserted laterally upon the axillary branch ; on the 

 other hand, it sometimes happens that the axillary branch is 

 adherent to the main shoot for some distance. 



The flowers of an inflorescence are either sessile or stalked, the 

 stalk being termed a pedicel. 



In accordance with the principles of branching laid down on 

 p. 18, the different forms of inflorescences may be classified as 

 follows : 



A. Racemose Inflorescences consist of a main axis (rhachis, peduncle), 

 bearing a number of lateral branches developed in acropetal (or centri- 

 petal) succession, constituting a monopodial branch-system. The lateral 

 branches do not usually grow longer than that portion of the main axis 

 which lies above their points of origin. If the lateral shoots of the first 

 order terminate in a flower without again branching, the inflorescence is 

 said to be simple ; but if they branch, it is compound. 



These inflorescences are also termed indefinite, not because the apical 

 growth of the main axis of its branches is unlimited, but because, owing 

 to the acropetal succession in the development of the flowers, the growth 

 of branches of a high order is arrested, by the development of a terminal 

 flower, earlier than that of branches of a lower order : for instance, the 

 growth of the secondary branches is arrested before that of the main axis, 

 that of the tertiary branches before that of the secondary branches, and 

 so on ; hence these inflorescences are sometimes termed centripetal. 



I. Simple racemose inflorescences : 



(a) With an elongated main axis: the lateral shoots spring from the axis 

 at some distance from each other. The three following forms may be 

 distinguished : 



(1) The spike, in which the lateral branches are flowers which are sessile 

 on the main axis, or have very short pedicels (Fig. 259 A) ; e.g. the inflor- 

 escence of the Plantain (Plantago). The small spikes of the Glumales are 

 termed spikelets. 



(2) The spadix, which differs from the spike only in having a thick and 

 fleshy axis ; a large bract forming a sheath, called a spathe, commonly 

 grows at the base of the inflorescence and envelopes it more or less ; e.g. 

 Arum and Bichardia. 



(3) The raceme, in which the lateral branches are flowers with pedicels 

 of nearly equal length, e.g. the Cruciferse, as the Eadish, Cabbage, etc. ; in 

 these the bracts of the individual flowers are not developed ; also Berberis 

 and others. 



(/3) With a short main axis ; the lateral branches are set closely together 

 on the short or flattened main axis. 



(4) The capitulum (head) in which the short main axis is conical or disc- 

 shape/I or even hollowed out, and is closely covered with lateral branches 

 int&e form of sessile flowers (Fig. 259 D), e.g. the Composite, as Dande- 

 lion, Sunflower : also the Scabious. The bracts (paleae) of the individual 



