THF. FLORA I. snOOT. 



420 



falls away aflcr the niaturil)- of the llo«er or fruit, is called oi 

 catkin, or an amenl. The flower clusters of the alder, willow, 

 (fig- S55)> poplar, and the staminate flower clusters of the oak, 

 hickory, hazel, birch, etc., are diiieiils. So characteristic is this 



Fig. 451. 

 Head of sunflijwer showing centripetal inflorescence of tubular flowers. (Photo 

 by the Author.) 



mode of inflorescence that the plants are called amentijeroiis, or 

 amentaceous. 



828. Anthesis of flowers with indeterminate inflorescence. — • 



In the anthesis of the raceme as well as in other corymbose forms 

 the lower (or outer) flowers being older, open frrst. The open- 

 ing of the flowers then takes place from below, upward; or from 

 the outside, inward toward the center of inflorescence. The 

 anthesis, i.e., the opening of the flowers of corymbose forms is 

 said to be centripetal, i.e., it progresses from outside, inward. 

 The anthesis of the fuller's teazel is peculiar, since it shows both 

 types. There are several distinct ad\antages to the plant where 



