158 SEVENTEENTH REPORT. 



much to do with the death of these phiiits. We have had such a 

 condition for four successive vears. Last winter there was growth 

 of some i)hints as late as the second week of December. In the 

 drier climates farther west this must be very unusual. 



It is often difficult to determine the exact time of death as a loss 

 of turgidity in winter is characteristic of our own hardy species'. 



I liave now seven species of Cactacea growing that have proved 

 hardy. Echinocereus viridifloris and Echinocactus simpsoni are 

 not killed by our most severe frosts but do not thrive and I am 

 inclined to think our humid climate is unsuited to these rotund 

 species, they tend to decay but perhaps I do not know how to 

 take care of them. Five species of Opuntia (arenaria. phaeocantha. 

 polyacantha, rafinesquii and vulgaris) grow well and are perfectly 

 hardy. All these become flaccid in winter with drooping stems 

 and shrunken joints. This change takes place in part before winter 

 sets in while it is particularly noticeable that with none of the 

 Arizona cacti was there any apparently response to the early light 

 frosts nor any loss oi turgidity until they were hit by real 

 winter weather. 



This gradual loss of turgidity in the fall, which is shown best 

 perhaps in our native species Opuntia rafinesquii. seems to be 

 equivalent to a deciduous habit and probably has much to do with 

 the ability of certain species of Cacti to stand our winters. 



Kalamazoo, Michigan, 1915. 



