I20 



BOTANY AND PHARMACOGNOSY. 



Modified Leaves. — Leaves are variously modified and 

 serve for other purposes than those already described. They may 

 be fleshy in character and serve as storehouses for nutritive mate- 

 rial, as the seed-leaves of the oak, or they may serve for the stor- 

 age of water, as in Agave and Aloe (Fig. 130). In some in- 

 stances, particularly when situated near the flowers, they lose 



Fig. 78. Group of transplanted wild plants showing variation in form of leaves. 

 A, Cinnamon fern {Osmunda cinnamomea) showing sporophylls (fertile leaves) and a cluster 

 of pinnatifid sterile leaves, the pinnae being linear-lanceolate and deeply pinnatifid; B, 

 wild ginger (Asarum canadense) showing basal, reniform, long-petiolate leaves with cordate 

 base and slightly pointed apex; C, young hickory (Hicoria ovaia) showing the odd-pinnate 

 (imparipinnate), s- to 7-foliate leaves; D, temate, decompound leaf of Virginia grape fern 

 (Botrychium virginianum); E, digitately compound leaves of cinquefoil iPotentilla). 



their green color, as in the dogwood, skunk cabbage and others. 

 In other cases they are modified so that they serve as a trap for 

 insects, as in species of Sarracenia and Drosera (Fig. yy). The 

 petiole may become enlarged and perform the functions of the 



