86 



THE LEAF 



^Im 





The actual motion is often faster than tliis, since tlie for- 

 ward movement is interrupted by retracings of tlie patli 

 and by up and down or oblit^ue deviations from tlie 

 level course. 



149. In case a twig or stem of anotlier plant is encoun- 

 tered, the tendril bends round it and the cla\\'cd extieuiities 

 catch in the bark (Fig. Id, (/). Tlie several divisions of 

 tlie tendril, with their numerous hooks, lay liold on the 

 newly found sujDport. and soon t\\ist about it, Mdiile the 

 rachis shortens by coiling (_Fig. T.3), in the manner char- 

 acteristic of tendrils. 



150. The leaves of insectivorous plants. — The haliitat 

 of insectivorous plants is chiefly marslies, lilce peat bogs. 



Tliose tliat the student will 

 be most likely to meet are 

 the Sundews and Pitcher 

 Plants. Tlie commonest, 

 Sundew QT)rosiri( rotuiidi- 

 foUa). is a little plant, 

 generally acaulescent, «ith 

 its five or six rounded 

 leaves spread otit horizon- 

 tally in a rosette from two 

 to four inches in diameter. 

 The leaves are thickly set 

 witli hairlike organs (Fig. 

 70). each tipped «itli a 

 glistening drop of sticky 

 secretion. To judge from 

 the number of small insects, 

 mainly gnats and flies, usually found sticking on the leaves 

 of the Sundew, it seems not luilikely that tlie plants exer- 

 cise upon them some attraction, perhaps tlirough an odor, 

 perhaps only by the brilliance of the clear secretion drops 

 sliining in the sun. and tlie color of the purplish glands. 



151. The gland-tipped outgrowths are tentacles. The 

 marginal ones are the longest, and when fully spread out 

 in all directions, double the total diameter of the leaf. If 



76. A leal of Drosera rolundifoHa, or 

 round-leaved Sundew (x2). 



