362 



A TEXTBOOK OF BOTANY [Cn. VII, 3 



Sometimes they are gigantic in size, as in the Martynia of 

 the western plains (Fig. 263). Everybody knows how abun- 

 dantly the weed seeds cling to our 

 clothes after walks in the fields in the 

 autumn; and they cling mostly by 

 hooks. The same result follows from 

 the presence of adhesive coverings to 

 fruits or seeds, as especially common in 

 epiphytes or parasites, for instance, 

 the Mistletoe. In these cases the 

 sticky seeds adhere firmly to the feet 

 FIG. 260. The Coco- o f perching birds until brushed off by 



nut, in section ; reduced. .,, , e 



It shows the air-hold- contact with rough parts of some 

 ing husk, the hard shell ^ ree the adhesiveness then serving to 



(black), endosperm or . . i .1 i- i 



" meat " (cross-lined), attach the seeds to the tree upon which 

 and central cavity con- they must grow. Adhesive seeds occur 



taming sap, or milk. . , i i ,1 



Below in the endosperm also in some water plants, which thus 

 can be seen the small become attached to the feet or feathers 



embryo, which lies just - . , . i i e 



under, and comes out in of wide-ranging water birds, many of 

 germination through one w hich travel so widely as to render 



of the "eyes." (From Le ,. , ,., ,, , . , 



Maout and Decaisne.) those plants cosmopolitan. Thus birds 

 come next after winds and ocean cur- 

 rents as agents of plant dispersal. t 



Second, fleshy fruits, with their edible, palatable pulp and 

 their bright, contrasting colors, are 

 easily found and eaten by animals, 

 through the bodies of which the seeds, 

 variously protected against injury from 

 digestive juices, pass uninjured, and 

 thus are dropped far from their places 

 of origin. This seems very clearly the 

 functional significance of edible colored 

 fruits in nature, all lines of evidence 

 converging upon this explanation. In 

 this way the smaller forms of fleshy fruits, especially the 

 diverse forms of berries and the smaller drupes, are scattered 



FIG. 261. Head of 



