igiQ. Pethybridge. — Heterocarpy in Picris echioides. 29 



the majority of the flowers situated on the disc. These 

 pecuUar ra3^-florets which, on the average, were only three 

 or four in number while the disc florets averaged about 

 sixty-three in each head, were situated opposite to the 

 four members of the outer whorl of the eight bracts referred 

 to above and consequently alternate with the inner four. 



It is these few ray-florets which produce the seeds 

 (one-seeded fruits) of the " peeled banana " type. After 

 flowering, and as the fruits ripen they become curved and 

 rather closely pressed into the concavity of their sheltering 

 bracts, and to some extent even, become gripped by the 

 edges of the latter. When ripe, therefore, they are not 

 nearly so easily dispersed by the wind as are the majority 

 of the now golden-brown fruits on the disc. The pappus- 

 stalk of the ray-fruits is shorter than that of the disc fruits, 

 and the pappus of the former is, perhaps, not quite so 

 well developed as that of the latter, but it is by no means 

 to be regarded as hypertrophied, or incapable of functioning. 

 One of the ripened ray fruits with its pappus is illustrated 

 on the accompanying plate (fig 2). 



A puff of wind acting on a dry ripe fruiting-head quickly 

 removes the disc fruits and leaves behind the few ray-fruits 

 gripped by the bracts. But these ray-fruits are also 

 ultimately dispersed, for plenty of heads were observed in 

 which all of the fruits, both disc and ray, were absent. 

 Since no heads, examined at an earlier stage, were found 

 in which the peculiar ray fruits were entirely absent, it 

 was concluded that both disc and ray fruits are ultimately 

 dispersed by the wind. 



The temporar}^ retention of the few ray fruits seems 

 rather a curious phenemenon. It serves, perhaps, to 

 explain how it is that these fruits are harvested with a 

 crop of ripe Clover or Lucerne, and thus find their way 

 into agricultural seed. But the advantage, if any, to the 

 plant under perfectly natural conditions is less obvious. 

 It occurred to me that possibly, during this period of 

 retention, dispersal by passing animals might occur. The 

 heads, at this period, are practically dead and dry, and 

 they break off somewhat easily. Owing to the hooked 

 hairs of the phyllaries, each head could be carried away 



^3 



