I02 



UTRICULARIA 



[CH. 



receive additions by the apical growth of the germinating 



turion. The bud-scales resemble reduced foliage leaves, but are 



specially suited to be protective organs. They are firmer than 



the other leaves and do not collapse on removal from the water. 



They are also less subdivided, and bear a more conspicuous 



development of hairs on their terminal segments the hairs of 



the successive leaves amounting, indeed, to a protective felt 



so that altogether they form an effective envelope for the bud. 



In Utricularia minor^ though the hairs 



are absent, a similar result is obtained 



by the leathery texture of the bud-scale 



and by its form, which is less divided 



than that of U. vulgaris. The contrast 



between the foliage leaf and bud-scale 



of U. minor is shown in Fig. 69 ^ and b. 



In U. intermedia the turion generally 



becomes free before the winter, and 



swims among the shore plants instead 



of spending the dead season at the 



bottom of the water. The fact that the 



turion is protected by an especially 



thick coat of hairs, probably permits 



it to lead this more exposed existence^. 



Figs. 143 ^ and 143 5, p. 220, show 



the bud-scale and normal leaf of this 



species. 



Though, under normal conditions, the turions are only formed 

 in the autumn, and carry the plant over the winter season, their 

 formation can be induced at any period of the year by condi- 

 tions of poor nutrition. In certain experiments made a few 

 years ago^, some turions of Utricularia minor., germinated under 

 starvation conditions on sand, after seventeen days had pro- 

 duced plants 14 cms. long. These were transferred to a culture 

 solution, and after tive days, when they had had time to become 



Fig. 69. Utricularia minor, L. 

 a, normal leaf of the shallow 

 water form, with a bladder; 

 h, leaf belonging to a turion. 

 (Enlarged.) [After Gliick, H. 

 (1906), Wasser-und Sumpfge- 

 wdchse, Bd. ii, Figs. 14 a and 

 b,p. 117.] 



iSchenck, H. (1885). 



Luetzelburg, P. von (19 10). 



