78 ARRANGEMENT OF FLOWERS ON THE STEM. [LESSON 11. 



form one cluster or inflorescence. The sorts of inflorescence of the 

 indeterminate class which have received separate names are chiefly 

 the following : viz. the Raceme, the Corymb, the Umbel, the Spike, 

 the Head, the Spadix, the Catkin, and the Panicle. 



200. Before illustrating these, one or two terms, of common oc- 

 currence, may be defined. A flower (or other body) which has no 

 stalk to support it, but which sits directly on the stem or axis it pro- 

 ceeds from, is said to be sessile. If it has a stalk, this is called its 

 peduncle. If the whole flower-cluster is raised on a stalk, this is 

 called the peduncle, or the common peduncle (Fig. 106,7?) 5 anc ^ tne 

 stalk of each particular flower, if it have any, is called 

 the pedicel or partial peduncle (/?'). The portion 

 of the general stalk along which flowers are dis- 

 posed is called the axis of inflorescence, or, when cov- 

 ered with sessile flowers, the rhackis (back-bone), and 

 sometimes the receptacle. The leaves of a flower- 

 cluster generally are termed bracts. But when we 

 wish particularly to distinguish them, those on the 

 peduncle, or main axis, and which have a flower in 

 their axil, take the name of bracts (Fig. 156, b] ; and 

 those on the pedicels or partial flower-stalks, if any,, 

 that ofbractlets (Fig. 156, b'). 



201. A Eaceme (Fig. 156, 157) is that form of flower- 

 cluster in which the flowers, each on their own foot- 

 stalk or pedicel, are arranged along a common stalk 

 or axis of inflorescence ; as in the Lily of the Valley, 

 Currant, Choke-Cherry, Barberry, &c. Each flower 

 comes from the axil of a small leaf, or bract, which, 

 however, is often so small that it might escape notice, 

 and which sometimes (as in the Mustard Family) disappears alto- 

 gether. The lowest blossoms of a raceme are of course the oldest, 

 and therefore open first, and the order of blossoming is ascending, 

 from the bottom to the top. The summit, never being stopped by 

 a terminal flower, may go on to grow, and often does so (as in the 

 common Shepherd's Purse), producing lateral flowers one after an- 

 other the whole summer long. 



202. All the various kinds of flower-clusters pass one into another 



p 



FIG. 156. A Raceme, with a general peduncle (p), pedicels (p r ), bracts (ft), and bract- 

 lets 



