GEOUP IV. PHANEROGAM1A : ANGIOSPERJYLE. 



491 



base by a number of bracts forming an involucre (Fig. 309 D i] which gives the 

 inflorescence the appearance of being one single flower. 



(5) The umbel, composed of a number of lateral branches, in the form of 

 pedicillate flowers, springing together from a very short axis which commonly 

 terminates in a flower (Fig. 309 C d) ; e.g. the Umbelliferas and the Ivy. The 

 bracts of the separate pedicels forming the rays are usually present in diminished 

 number ; they form an involucre. 



II. Compound racemose inflorescences are formed when the lateral shoots 

 which bear flowers, as described above, are again branched, or, in other words, 

 when inflorescences of the types above enumerated are united to form a larger 

 inflorescence ; for instance, when several capitula are arranged on the main 

 axis in the same way as the flowers of a raceme. The same terms are applied 

 to the first ramification of the compound inflorescence as to the simple ones 

 described above ; the above-mentioned example, for instance, is a raceme of 

 capitula, and is termed a capitulate raceme. Compound inflorescences may be 

 classified as follows : 



(a) Homogeneously compound; ill these the branches of the first and second 

 (or higher) orders 

 are of the same 

 character. 



(6) The com- 

 pound spike ; in 

 this form many 

 simple spikes are 

 arranged on the 

 main axis of the 

 inflorescence in 

 the same way as 

 the flowers in a 

 simple spike, or, 

 in other words, 

 the main axis of 

 the spike bears 

 secondary spikes 

 instead of single 



flowers, e.g. the inflorescence of Wheat, Bye, etc. 



(7) The compound raceme ; in this case smaller racemes grow on the main 

 axis of the raceme ; the ramification is in many cases still further repeated in 

 such a way that it is more complex at the base of the primary raceme than 

 towards tbe apex, e.g. the Grape-vine (Fig. 309 B). 



(8) The compound umbel (Fig. 309 C). This is far more common than a 

 simple umbel, and is in fact usually called an umbel ; the separate simple 

 umbels (Fig. 309 C d) are then called umbellules, and their respective involucres 

 are inv>lucels. 



(|8) Heterogeneously compound inflorescences; in these the branches of the 

 different orders are dissimilar. In consequence of this so many complicated 

 forms arise that it is impossible to enumerate and name all the combinations. 

 As examples, the following will only be mentioned : the capitulate raceme, 



FIG. 309. Diagrams of the varieties of racemose inflorescences. 

 A Spike. B Compound raceme. C Compound umbel; d rays 

 of the umbel; i involucre; d x secondary rays of the umbellules; 

 i 1 involucel. D A capitulum ; i involucre ; b flower ; p bracts. 



