78 ARUANGKMENT OF FLOWERS ON THE STEM. [lESSON 11. 



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

 indi'tenninate chiss which have received separate names are chiefly 

 the following: viz. tlie Haceme, the Cori/mb, 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 supjiort 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. 156, />) ; and the 

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

 the pedicel or partial peduncle (p'). The portion 

 of the general stalk along which flowers are dis- 

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

 ered with sessile flowers, the rhachis (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 havis 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 RaCPniC (Fig. 156, 157) is that form of flower- 

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

 X--A 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 jiass one into another 



FIG. 150 A Raceme, with a general peduncle (p), pedicels (//), l)racts (i), and bract- 



