37° THE FRUIT 



the wings are formed by adherent bracts. Examples 

 of winged seeds are those of the pine and of the tropical 

 genus Zanonia. 



Examples of plumed fruits are those of the " old 

 man's beard " (the wild clematis), where the styles are 

 persistent in the fruit and are clothed with long silky 

 hairs, and those of the dandelion, groundsel, thistle 

 (" thistle down "), and of many other members of 

 the Compositae. Here there is a special plumed structure, 

 the pappus, surmounting the indehiscent one-seeded 

 fruit. Examples of plumed seeds are those of the 

 willows, and of the various species of willowherb (the 

 riverside " codlins and cream," the " rosebay " willow- 

 herb of open woods, and the other species). Here the 

 capsule opens and sets free the crowds of tiny seeds 

 which drift about, floated in the air by their very fine 

 silky hairs. 



(2) Dispersal by Animals. — Some indehiscent fruits 

 bear hooks which catch on passing animals and stick to 

 their coats, the fruits being readily pulled off the plant. 

 Brushed off later on, the seed may germinate at a distance 

 from the parent plant. The hooks are sometimes out- 

 growths of the pericarp (" cleavers," Galium aparine), 

 or the hook is formed from the style (herb-bennet, 

 Geum urbanum). In the burdock {Arctium), a member 

 of the Compositae, the bracts surrounding the flower 

 head are hooked, and the head when in fruit is easily 

 detached, so that it is carried off as a whole, and the 

 dry one-seeded fruits drop off. All these fruits very 

 readily stick to the trousers or skirt as the wearer 

 brushes against the plants. 



Animals are also constantly distributing dry fruits 

 and seeds even if these have no special means of adhering 

 to them — carrying them about in the crevices of their 



