2i: 



Minnesota Plant Life. 



the power of the purple substances in the spathe, together with 

 the respiratory activity of the fleshy spike, to increase the tem- 

 perature. Tn the jack-in- 

 thc-pul])it flower the ])ecu- 

 liar httle chflj-shaped sterile 

 end of the spike is probably 

 a respiratory organ and to- 

 gether with the special col- 

 oring substances does its 

 part in raising the tempera- 

 ture. Small insects learn 

 that these flower clusters 

 oft'er them c o m f o rt able 

 shelter and seek them, and 

 as a result pollination is se- 

 cured. The flowers of most 

 of the arums depend upon 

 this ability to furnish heat 

 rather than upon perfumes, 

 gaudy colors or the secre- 

 tion of nectar to attract 

 their insect visitors. 



Burrowing bulbs. A n - 

 other curious feature in the 

 lives of many arums is the 

 burrowing habit of the 

 young bulbs. If a flower 

 pot about six inches tall is 

 filled with rich loam and 

 some seeds of the skunk- 

 cabbage or jack-in-lhe-pul- 

 pit are planted about half 

 an incii below the surface 

 and permitted to germinate, 

 the plantlets when they 

 burst forth will at once be- 

 gin the formation of bulbs 

 bv e\i)anding the lower 

 portions of their stems iiUo 



Fir..!*7 A >kimk-cal)bagc in early spriiitc, be- 

 fore the leaves have unfolded. The purple 

 hood covering the flower cluster is slio\i ii mi 

 one side. After Atkinson. 



