LESSON 11.] DETERMINATE INFLORESCENCE. 



81 



210. A Catkin or Ament is the name given to the scaly sort of spike 

 of the Birch and Alder, the Willow and Poplar, and one sort of 

 flower-clusters of the Oak, Hickory, and the like ; on which ac- 

 count these are called Amentaceous trees. 



211. Sometimes these forms of flower-clusters become compound. 

 For example, the stalks which, in the simple umbel such as has 

 been described (Fig. 159), are the pedicels of single flowers, may 

 themselves branch in the same way at the top, and so each become 

 the support of a smaller umbel ; as is the case in the Parsnip, Cara- 

 way, and almost the whole of the great family of what are called 

 Umbelliferous (i. e. umbel-bearing) plants. Here the whole is 



termed a compound umbel; and the smaller or partial umbels take 

 the name in English of umbellets. The general involucre, at the 

 base of the main umbel, keeps that name ; while that at the base 

 of each umbellet is termed a partial involucre or an involucel. 



212. So a corymb (Fig. 158) with its separate stalks branching 



again, and bearing smaller clusters of the same 

 sort, is a compound corymb ; of which the Moun- 

 tain Ash is a good example. A raceme where 

 what would be the pedicels of single flowers 

 . I ($ become stalks, along which flowers are disposed 

 \ Y' on their own pedicels, forms a compound raceme, 

 (TV\ ) a * i n the Goat's-beard and the False Spikenard. 

 But when what would have been a raceme or a. 

 corymb branches irregularly into an open and 

 more or less compound flower-cluster, we have 

 what is called 



213. A Panicle (Fig. 163); as in the Oat and 

 in most common Grasses. Such a raceme as that 

 of the diagram, Fig. 156, would be changed into 

 a panicle like Fig. 163, by the production of a 

 flower from the axil of each of the bractlets fr. 



214. A Thyrsus is a compact panicle of a pyramr- 

 idal or oblong shape ; such as a bunch of grapes, 

 or the cluster of the Lilac or Horsechestnut. 



215. Determinate Inflorescence is that in which the flowers are from 

 terminal buds. The simplest case is where a stem bears a soli- 

 tary, terminal flower, as in Fig. 163*. This stops the growth of 



FIG. 1C3. A Panicle 



