80 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOVT. 



Each of the four valves, the dehiscence being 

 loculicidal, consists of two half-carpels, and the ends 

 of the hairs are caught and pressed by the edges of 

 the carpels. Now, the effect of this curious arrange- 

 ment is that as the valves in drying curl and become 

 miore and more divergent, the carpels at the same 

 time slackening their hold of the hairs, the seeds 

 are liberated one by one and scattered on the wind. 

 No doubt the special provision has in this case been 

 rendered necessary on account of the shape of the 

 capsule being ill-adapted to afford the seeds a fair 

 start. Another arrangement facilitating the despatch 

 of the seeds is seen in the feathery globe of fruit 

 formed by the dandelion {Taraxacum) so familiar to 

 everyone. Tragopogon has a dow^ny sphere of the 

 same description, but four or five times bigger. 

 Here, as in the thistle, the capitulum is closely 

 invested by the involucre while the fruit is maturing. 

 If a flower-head in this stage be examined, each 

 fruit is seen to terminate above in a slender beak 

 which bears at its apex a pencil of silky hairs. 

 When the fruit is ready, the bracts spread and 

 become recurved, the floor of the receptacle becomes 

 convex, and the brushes expand into parachutes. 

 Having now only a very slight attachment to the 

 flower-stalk, a moderate breeze suffices to dislodge 

 and scatter ripe fruits. By means of its hairy 

 parachute, dandelion-seed easily floats along on a 

 current of air. It cannot be said, however, that in 

 Taraxacum or Tragopogon the provisions for transport 

 are equal to those of the thistle. These fruits are 

 somewhat heavier, and in very still air will fall 

 straight but slowly to the earth. They are not 

 therefore adapted to be carried so fast or so far as 

 thistle seed ; but this disadvantage may be more 

 than counterbalanced by their penetrating power, 

 which we shall now endeavour briefly to explain. 



The parachute of hairs is no doubt a very perfect 

 contrivance so far as mere transport is concerned ; but, 

 besides this, the solid portion of the fruit in its upper 



