COiMPOUND RACEMOSE INFLORESCENCES 91 



are seen in the hyacinth, lily-of-the-valley, wallflower, snapdragon, 

 mignonette, and currants. 



The corymb (C, Fig. 39) has its pedicels of different lengths, 

 those at the base of the rachis being longest, followed by pedicels 

 of decreasing length upwards ; all the flowers are nearly on the 

 same level. Examples occur in candytuft. 



(iii) With shortened axis and sessile flowers — 



The capitulum or head (A, Fig. 40) possesses a short thick 

 rachis termed the receptacle (r) upon which are a number of 

 closely-packed, small, sessile flowers. Examples are seen in the 



A B 



Fig. 40. — Racemose indefinite inflorescences with short axes. 

 A A capitulum ; r "receptacle" ; z involucre of bracts ; ?z scale-like 

 bracteole or palea. B Simple umbel ; ; involucre of bracts. 



daisy, marigold, dandelion, groundsel, and all the Compositse 

 (Chap, xxxiii.). 



Usually one or more dense whorls of bracts surround the 

 whole head and are collectively termed the involucre of the 

 capitulum : in many instances a small, scale-like bract termed 

 a palea is also associated with each flower of the head. 



(iv) With shortened axis and stalked flowers — 



The umbel {B, Fig. 40). In this form the main axis is short 

 and bears a number of flowers with stalks of similar length. 

 Examples occur in ivy, cowslip, and onion. 



B. Compound Racemose Inflorescences. — In these the 

 main axis does not bear sessile or pedicellate flowers directly, 

 but bears lateral branches which are themselves inflorescences. 



