512 



BOTANY 



Less commonly, as in some of the Cycads and Ginkgo, and species of 

 Ephedra, the outer part of the seed becomes fleshy and edible, and 

 probably attracts animals, which help to distribute the seeds ; 

 and in Juniperus the scales of the cone 

 become sweet and pulpy, and are readily 

 eaten by birds, through whose bodies the 

 seeds pass uninjured. 



Among the simpler Angiosperms the seeds 

 are borne in dry carpels, which are often 

 indehiscent, and there is no special provision 

 for the distribution of the seeds, which fall 

 off, and must depend on being washed or 

 blown away, in order to be distributed to any 

 considerable distance. 



In the better-developed forms the carpels 

 develop into a definite capsule, which often 

 opens in such a way as to scatter the seeds 

 with a good deal of force. This is illus- 

 trated by species of Viola and Irnpatiens 

 (Fig. 478). 



The provisions for distributing seeds through the agency of the 

 wind are numerous and varied. In many plants e.g. Bignonia, 

 Catalpa, Tecoma, etc. the seeds are provided with delicate membra- 

 naceous wings, similar to those in the Pine. In others, like the 

 Milkweed (Asclepias), Willow-herb (Epilobium), Cotton, and many 

 besides, the appendages of the seed are delicate hairs, which serve 

 the same purpose as the flat wings of other seeds. 



Sometimes it is the fruit containing the seed which bears the fly- 

 ing apparatus. This is seen in such winged fruits as those of the 

 Elm and Maple, or the down attached to the fruits of many Com- 

 positae, like the Dandelion and Thistle. 



FIG. 478. Impatiens bal- 

 samina, showing explo- 

 sion of the ripe capsule. 

 (After BAILEY.) 



Transportation by Water 



While many seeds and fruits are distributed by air-currents, some 

 forms depend upon water for their transportation. Of the few forms 

 which are regularly transported by salt water, the Cocoanut is per- 

 haps the best known, the fibrous pericarp perfectly protecting the 

 enclosed seed from the injurious action of the salt water. While 

 but few forms of seeds and fruits are specially adapted to water 

 transport, nevertheless, the current of large rivers is an important 

 factor in the distribution of seeds and fruits, which are either floated 

 free in the water, or carried along with masses of debris washed 

 down from the banks. 



