440 



PART IV. CLASSIFICATION. 



flowers (Fig. 259 D p) are sometimes wanting ; but the whole head is sur- 

 rounded at the base by a number of bracts forming an involucre (Fig. 

 259 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 com- 

 monly terminates in a flower (Fig. 259 Cd) ; e.g. the Umbelliferae 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 in- 

 florescence as to the simple ones described above ; the above-mentioned 



example, for 

 instance, is a 

 raceme of capi- 

 t u 1 a, and is 

 termed a capi- 

 tulate raceme. 

 Compound in- 

 florescences may 

 be classified as 

 follows : 



(a) Homogene- 

 ously compound : 

 in these the 

 branches of the 

 first and second 

 (or higher) or- 

 ders are of the 

 same character. 



(6) The compound spike 5 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, Rye, 

 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 the apex, e.g. the Grape-vine (Fig. 259 B). 



(8) The compound umbel (Fig 259 C). This is far more common than a 

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

 umbels (Fig. 259 C d) are then called umbellitles, and their respective invol- 

 ucres are incolucels. 



(/3) Heteroyeneotmly compound iu.iorescznces ; in these the branches of the 



FIG. 269. Diagrams of the varieties of racemose inflorescences. 

 A Spike. B Compound raceme. C C impound umbel ; ti rays 

 of the umbel ; i involucre ; d secondary rays of the umbsllnles ; 

 i, involucel. D A capitulum ; i involucre ; b flower; p bracteoles. 



