38 



OLOSSAJir OF 



LONGITUDINAL SECTIONS. 



The pupil should make a constant practice of splitfimj llowers 

 throufjh the centre (best done from below upwards with a 

 very sharp knife), and drawing the section thus presented. 

 Such a drawing is exceedingly useful in connection with 

 the floral diaj^ram, as still further exhibiting the relation of 

 the parts to each other. 



Fig. 226 is a good example. Here the relations of tlie 

 parts can be seen at a glance. 



COMPOSITE FLOWERS. 



.\ full description of a Composite flower involves some par- 

 ticulars of a special kind ; for convenience, tlierefore, the 

 various terms in use are collected together here. 



Inflorescence. 



Under this heading describe the arrangement of the heads, 

 using the terms already explained — solitary, cymose, 

 racemose, corymbose, spiked, etc. 



Head. 



The assemblage of florets (few or many) on a common 

 receptacle. 



Parts of the Head. 



Floretts : the small single flowers which in tiie aggregate 

 make up the head. These are 



(a) Lii/tilatn, when the corolla is prolonged on one side 

 into a flat strap-shaped piece (Fig. 227). 



Chj Ttthular, when the corolla is not thus prolonged, 

 but is regularly developed all rou (Fig. 228). 



Km;eptacle: the place upon which the florets stand. 



Invoiucirk : the circle or circles of bracts which surround the 

 head. 



Kinds of Head. 



LtoirLiKixiRAL : when all the florets of the head are ligulate, 

 as in Dandelion (Fig. 229). 



TuHVurumAU : when all the florets are not ligulate; and 

 such heads are 



(a) Discoid, if iiii me nt'rets are tui)ular as in Thistle. 



(b) Radiate., if the florets round the margin of the 

 head (rny-fiorrtM) are ligulate, while the central ones 

 (disk-flor^isj are tubiilar, as in Sunflower (Fig. 2.'J0). 



Fig. 226. 



Fl|f. 227. 



Fig. 22& 



Ffpr. 229. 



ray-floret 



fllsk- floret chaff 



invoIiKTC Fig. 230. 



