40 PART I. ORGANOGRAPHY. 



it is supposed, to the intoxicating effects of the secretion which 

 they imbibe, they seldom escape, but are drowned in the water 

 within the pitcher, and their decaying bodies 

 form a rich manure which goes to sustain the 

 life of the plant. The leaves of Darlingtonia, 

 Fig. 134, a related plant of California, catch 

 insects in much the same way, and make the 

 same use of them. And the East Indian 

 Pitcher-plant, Nepenthes, Fig. 135, has a leaf, 

 the lower part of which serves as a blade, 

 performing the proper functions of a foliage 

 leaf; the middle portion is developed into a 

 tendril, by means of which the plant climbs 



Fig. 135. — Leaf of the j ., . . . . , , . . 



East Indian pitcher- and the apical portion is developed into a 

 p ant („ epent es) pitcher which, like that of Sarracenia, en- 



traps insects and utilizes them for food. 



There are several other plants also which possess insectivor- 

 ous habits, and whose leaves are modified more or less with 

 reference to these habits ; among them are the Bladder-worts, 

 which develop little, bladder-like crustacean traps on their 

 leaves; the Pinguiculas, whose leaves are glandular on the upper 

 surface, and which entrap and devour insects somewhat after 

 the manner of the Sundew, though in a ruder fashion, and the 

 Australian Cephalotus, which bears among its ordinary leaves 

 others in the form of very perfect pitchers. 



Practical Exercises. 



1. Compare the following leaf forms and note their resemblances and dif- 

 ferences : The scales of a Hickory bud, the fleshy scales of a Lily bulb, the 

 large spines on the Prickly-pear Cactus, the different forms of leaves on the 

 Barberry, the leaves of the Pitcher-plant, the petals of the Rose, and the leaf 

 of the Maple. 



2. Determine what organs are represented, respectively, by the tendrils of 

 the Grape, the thorn of the Plum, the flattened joints of the Prickly-pear 

 Cactus, and the pod of the Pea. 



3. Describe the following simple leaves as to their venation, the parts 

 present, general outline, apex, base, margin, surface and texture, using the 

 correct botanical terms : Those of the White Oak, Stramonium, Hard Maple, 

 Birch, House Ivy, Solomon's Seal Onion, White Pine, Timothy Grass, and 

 Live-for-ever. 



4. Describe the following compound leaves as to the parts present, the 

 plan of compounding, the number of leaflets and the general outline, apex, 



