650 



BOTANY OF THE LIVING PLANT 



Corolla, petals 5, gamopetalous, superior. 



Androecium, stamens 5, alternating with the petals, epipetalous, inserted 

 by separate filaments upon the throat of the corolla, but with the anthers 

 united laterally into a tube (syngenesious). 



Gynoecium, carpels 2, antero-posterior, syncarpous. Ovary inferior, uni- 

 locular, containing a single anatropous ovule. Style elongated, and bearing 

 up through the tube of the anthers the two lobes of the stigma, which diverge 

 beyond it in the later stages of flowering (Fig. 500, vii.). 



'■■■■ W 



Fig. 500. 



I. Whole capitulum of Chrysanthemum. II. same in median section. III. disc- 

 floret in earlier (male) condition. IV. same in later (female) condition. V. ray- 

 floret. VI. style and stigma. VII. disc-floret in section. VIII. floral diagram. 



The white ray- floret consists of : 



Calyx, as before. 



Corolla, petals 5, gamopetalous ; tubular below, elongated above into a 

 narrow strap-shaped ray representing the three anterior petals, the two 

 posterior being here obsolete. 



Androecium, absent. 



Gynoecium, as before (Fig. 500, v., VI.). 



Fruit. Each flower produces a dry achene, which at maturity is shaken 

 out from the protecting involucre. There is no pappus. 



Pollination. The mechanism is here essentially the same as in Groundsel, 

 but with addition of the attractive ray-florets. In the first flowering stage the 

 disc-florets offer pollen, in the second stage the expanded stigmas to the insects 

 that are attracted by the colour and honey (iii. iv.). Any crawling insect will 

 effect crossing. But if this fails self-pollination is also possible. 



(44) A third more elaborate type is seen in Cornflower (Centaurea Cyanus, 

 or C. montana will serve). The general structure is the same, but the ovoid 

 head is tightly enclosed by the appressed bracts with brown margins. The 

 receptacle is flat and bristly. The flowers are all tubular, but the outermost 

 are neuter, and coloured, with long tubular two-lipped and 5-lobed corolla, 

 and abortive stamens and ovary. The inner florets are hermaphrodite, and 

 of the usual type, with pappus of short unequal bristles. The lower part of 

 the corolla-tube is tubular and narrow, the upper is globose, bearing five 



