228 



BRITISH FLOWERING PLANTS 



enabling the cotyledons to make their escape. The 

 embryo swells up and the radicle usually bursts through 

 the side of the fruit beneath the calyx limbs ; it then 

 pierces the latter, entering by the outer 

 face, and pushing on through both sides, 

 enters the ground, thus pinning the 

 fruit to the soil, while the cotyledons 

 are pulled out in a comparatively short 

 time into the light. 



In V. olitoria the fruit is laterally 

 compressed. The chamber containing 

 the seed is in the middle, with the two 

 empty chambers on one side and a 

 corky mass on the other. 



In V. carinata the fruit is not flat- 

 tened laterally, but compressed rather 

 from front to back, so as to be almost 

 boat-shaped. 



In V. auricula the two hollow cells 

 are much larger than that containing 

 the seed. 



Lastly, in V. dentata the hollow 

 cells are smaller than the fertile one, 

 and each lies in a separate projection 

 of the fruit wall, which is also produced at the two 

 ends. 



Fig. 148.— Seedling of 

 Vahricmella coro- 

 nata. x 4. 



DIPSACE^ 



Each floret is surrounded by an involucel ; they are 

 rendered conspicuous by being collected into a head. 

 Our species are protandrous. Honey is secreted by 

 the upper part of the ovary, and concealed in the tube 

 of the corolla. 



DiPSACUS 



Stifi' bristles prevent insects from walking on the 

 flower-heads, so that they must touch the anthers and 

 stigmas with their heads rather than with their feet. 



