476 



STRUCTURE AND LIFE HISTORIES 



from the pouches, and snap over in, toward the center, 

 thus dusting the insect with pollen, which is then trans- 

 ferred to the stigma of the next flower visited by the 

 insect. 



The corpse-plant, or Indian-pipe {Monotropa uniflora), is 

 of interest because, although belonging in a sympetalous 



Fig. 360. — Milkweed {Asdepias sp.). a, flower-bud; b, flower; c, 

 very young pod; d, older pod in section, showing seeds; e, section of 

 flower; /, top view of flower, showing the 5 Jioods of the crown, each with 

 a horn incurving to the stigma; between the horns are the cleft glands 

 (shown enlarged at g), to which the pollinia are attached. 



family, it is polypetalous, and further because, Hving 

 entirely as a saprophyte (or, possibly, as a root-parasite), it 

 has entirely lost the power to make chlorophyll, and hence 

 the power of photosynthesis (Fig. 230, p. 323). 



419. Milkweed Family (Asclepiadaceae). — The milk- 

 weeds^ present a most curious and interesting modifica- 



^ So called because they contain a milky juice or latex. 



