142 THE FLOWERING PLANT. 



fruit, as in dandelion, "thistledown," Sec. The dandelion is of 

 further interest because the peduncle, which during ripening is 

 directed along the ground, raises itself so that the fruits can 

 readily blow away. The perianth of cotton-grass (really a sedge) 

 consists of bristles which grow out into long hairs ; a crown of 

 hairs is found on the seeds of willow-herb, while a more general 

 covering of hairs is present on willow and cotton seeds. The seed 

 of storlv s-bill, a near relative of the geranium, possesses a long 

 feathery awn adapted for catching the wind. The base of the 

 awn is also twisted, and this part when moist tends to screw the 

 pointed seed into the ground. 



Many fruits or seeds, especially those of trees, are provided 

 with an expanded "wing," of various nature. In lime the stem 

 of a flower cluster is provided with a large adherent bract, and 

 in hornbeam the single fruit is in the axil of a trilobed bract. 

 The fruits of maple, sycamore (fig. 58), birch, ash, and elm are 

 themselves winged, and there is a membranous margin in those 

 of dock and parsnip. Scotch fir presents an example of winged 

 seeds, 



(4.) Animals help to distribute seeds and fruits in a variety of 

 ways. Many fruits are provided with hooks, and some with 

 sticky hairs, by which they become attached to the coats of 

 animals. Such cases are found among plants low in stature, 

 where alone they would be useful. The calyx of forget-me-not 

 and fruits of burdock and cleaver are common British examples. 

 In Plumbago the calyx with its viscid glandular hairs (p. 112) 

 persists and answers the same purpose. 



Succulent fruits appear to be especially adapted by their colour, 

 scent, and edibility to attract animals, particularly birds. The 

 well-protected seeds they contain are able to resist digestion, and 

 are, doubtless, frequently transported to considerable distances. 



Small portions of earth containing seeds must also frequently 

 became attached to various animals. 



Germination. — This simply means the development of a seed 

 into a young plant up to a period when it is able to obtain food 

 from the exterior. The embryo contained in a seed is in a 

 dormant state, and if the conditions are unfavourable, may so 

 remain for a considerable length of time. A seed when kept 

 damp and exposed to the air will germinate if the temperature is 

 suitable (say about 35 ° centigrade). Take, for example, an ex- 

 albuminous seed, like that of bean. The contained embryo first 

 swells and bursts the seed-coat. The radicle elongates, and then 

 the plumule, at first strongly curved, raises itself from between 

 the cotyledons and rapidly grows. The cotyledons remain within 

 the seed-coat, and here simply serve as stores of reserve materials, 



