THE AMERICAN BOTANIST 83 



Aralia Trifoliata. — Miss Sarah F. Sanborn writes that 

 there is considerable difiference in the size of the ground nut 

 plants (Aralia trifoliata) in her vicinity and that only the 

 larger ones appear to be fertile. She expects to examine the 

 plants this spring in order to verify this impression. As we 

 recall the plants the majority of them bear blossoms but it may 

 be possible that only the more robust are able to bring their 

 seeds to maturity. We often too hastily assume that the sole 

 cause of a herb or tree's failing to fruit is a lack of pollen. 

 As a matter of fact many trees, such as plums, fail to fruit 

 though pollinated because their stigmas are not affected by 

 some sorts of plum pollen. In other trees, if too many young 

 fruits set, the surplus fruits are promptly cut off. The editor 

 once pollinated a number of paw^paw flowers in each of which 

 there were several pistils but which commonly ripen only a 

 single fruit for each flower. In this experiment several pistils 

 began to grow, but the plant would not stand for the extra 

 number and cut them off before much growth occurred. 



Change of Sex in Arisaema. — It is a fact well known 

 to those acquainted with Jack-in-the-pulpit (Arisaema triphyl- 

 luni) that the character of the flowers varies w'ith the individ- 

 ual in some cases being staminate and in others pistillate or 

 monoecious. Something of the same kind is found in other 

 species of this genus and a Japanese botanist writing in Kew 

 Bulletin, asserts of the Japanese Arisaema Japonicum and A. 

 ringens, that they not only bears the two kinds of flowers on 

 separate plants, but what is most remarkable, that the sex of 

 the flowers varies from year according to the amount of plant 

 food the individual plant has at command. When a plant 

 bears pistillate or female flowers one year it may be made to 

 bear staminate or male flowers the next by curtailing its 

 nourishment. This is quite in harmony with the general law 

 prevailing throughout the plant world that when flowers are 

 of separate sexes, the female flowers always appear on the 



