i 7 8 



GROWTH AND WORK OF PLANTS 



Jack-in-the-Pulpit, Indian Turnip. 

 (Arisama triphyllum.) 



284. The Indian turnip inhabits moist, shady woods or 

 groves, and flowers from April to June. Its underground 



t i perennial stem is a corm (paragraph 



80) which is very acrid to the taste. 

 The annual flowering shoot is formed 

 in the bud at the apex of the corm 

 during autumn and winter. The 

 plants are about 30 cm. (i foot) high. 

 The leaves are divided into three 

 leaflets. The flower shoot is very odd 

 and interesting. It is in the form of 

 a spadix, a cylindrical structure, the 

 free end sterile and with the small 

 imperfect (either staminate or pistil- 

 late) flowers crowded around the lower 

 part. The spadix is enclosed in a 

 leaf-like structure, forming a broad 

 cylindrical tube (the "pulpit") below, 

 and above tapering into a strap- 

 shaped part (spathe) which bends 

 forward over the pulpit. In some 

 plants the staminate and pistillate 

 flowers are borne on the same spadix 

 (plants monoecious), but usually they 

 are all of one kind on a spadix 

 (plants dioecious). 



285. A little observation will show 

 that the pistillate plants are the larger 

 and have larger corms, while the 

 staminate plants are smaller. The 

 larger corms have more stored food 

 and thus produce a larger aerial shoot. But why they should 

 produce pistillate flowers is not so clear, though it probably 



I 



Fig. 133. 



Jack-in-the-pulpit or Indian 

 turnip (Arisaema triphyllum), 

 spathe removed, showing spadix; 

 the two upper figures with pistillate 

 flowers, lower figures with stami- 

 nate flowers. 



