THE BOTRYOSE TYPE. 



147 



so resemble the raj-s of an umbrella ; whence the name, and 

 whence also the pedicels or partial peduncles of an umbel are 

 termed its Rays. The bracts, brought by the non-development 

 of internodes into a depressed spiral or apparent (or sometimes 

 real) whorl, become an involucre. (264.) An umbel or any 

 similar cluster when sessile (without a common peduncle) , and 

 the parts crowded, is sometimes called a Fascicle (or the pedicels 

 said to be fascicled} ; but this term has been differently defined. 

 (280.) It is better not to use it for any special kind of inflores- 

 cence, but simply in the sense of a bundle of whatever sort. 

 This will accord with the sense in which it is applied to an 

 aggregation of leaves. (248.) 



275. A Head or Capitulum (Fig. 285) is a globular cluster of 

 sessile flowers, like those of Red Clover, Button-bush, and 

 Plane-tree. The pedicels need not be absolutely wanting, but 

 only very short. An umbel 

 with pedicels much abbrevi- 

 ated thus passes into a head, 

 as in Eryngium, &c. And 

 a head with rhachis elongated 

 passes into a spike. The 

 short rhachis of a head very 

 commonly takes the name of 

 receptacle. (2G5.) The whole 

 may be subtended by con- 

 spicuous bracts forming an 

 involucre (264) as in Fig. 

 286, or may be destitute of 

 any, as in Fig. 285. On ac- 

 count of the compactness 

 and mutual pressure under 

 growth, the bracts among 

 the flowers of such heads (normally one subtending each blos- 

 som) are apt to be rudimentary, reduced to little scales, or 

 abortive, or completely wanting. In the latter case, the recep- 

 tacle is said to be naked (nude), i.e. naked of bracts: when 

 they are present, it is paleate or chaffy. A peculiar sort of head, 

 not undeserving a special name (though this is not necessary 

 in descriptive botany) , is the 



ANTHODIUM, the so-called Compound Flower of the earlier 

 botanists, which giA r es the name to the vast order of Composite. 



FIG. 285. Cephalanthus occidentalis, the Button-bush; a pair of leaves, and a 

 terminal peduncle bearing a dense head (capitulum) of flowers. 



