176 



FIELD AND WOODLAND PLANTS 



of the ovary. Sucli a whorl is known as the piippu.s, and it fre- 

 quently enlarges as the fruit riiiens, forming a kind of parachute 



that allows the fruit to be 



,,J^^^t 





CAFiTULUit OR Flower-head of the 

 Marigold, showing the involucre or 

 whorl of overlapping bracts. 



carried great distances by the 

 wind. The hairs of the pappus 

 are often sessile on the fruit, 

 but sometimes mounted on the 

 summit cf a slender stalk, as in 

 the Dandelion. Finther, the 

 hairs which constitute the pappus 

 may be simple or feathered. 



The corolla frequently con- 

 sists of five petals, united into 

 a tube with as many teeth ; but 

 it is often ligulate or strap- 

 shaped, in which case the 

 presence of five petals is often 

 denoted by five minute teeth at 

 the tip. 



Where stamens exist tliey 

 are five in number, attached 

 to the petals, and the anthers are generally united in such a 

 manner that they form a tube within the tube of the corolla. 



Fertilisation is brought 

 about much in the same way in 

 many of the composite flowers : 

 — The anthers ojjen inwards, 

 discharging their jjollen within 

 the tube formed by themselves, 

 and just above the stigma 

 which, as yet, is immature. 

 The style then lengthens, push- 

 ing its way up through the 

 anther-tube, and brushing up 

 the pollen by means of the 

 tufts of hairs on its surface. 

 At this stage a dense cluster of 

 pollen cells, completely cover- 

 ing the top of the style, may be seen projecting above the tube 

 of the corolla, and the pollen is sooner or later scattered, the 

 distribution being aided greatly by the various insects which 



I'LORETS OP A COiU>0SITF, FLOWEH. In 

 liK. 1 the corolla is strap-shaped ; in 

 lig. 2 it is tubular. 



