FLOWERS OF ACER SACCHARINUM. 205 



5th and the first seeds ripened on May 31st, a period of forty- 

 one days. The first leaves appeared on April 10th and these 

 were for the most part, quite full-grown by the time that the 

 first fruits were matured. 



SuMMAEY.^ — To summarize briefly; it is found that many 

 staminate flowers contain pistils of which at least some are func- 

 tional, but apparently require cross-fertilization. As the number 

 of stamens in the flowers increases, the tendency is away from 

 liermaphroditism and polygamy. All pistillate flowers contain 

 stamens, but these stamens are either rudimentary, or in a few 

 cases where functional, are so far retarded in their growth as to 

 hi' practically useless. Considerable variation in flower structure 

 and in the time of flowering exists among different trees. There 

 is a strong tendency for the flowers of one tree to fertilize those 

 of another tree, since the pistillate flowers of each individual 

 tree appear several days later than its staminate flowers. 



The foregoing evidence suggests that Acer saccJiarinum 

 may only recently have become monoecious and that there is a 

 rather marked tendency towards the production of a large num- 

 ber of stamens, since the six-stamened flowers are doing most of 

 the fertilizing, while the four-stamened flowers are retarded in 

 growth by the pistil. There now appears also to be in this species 

 a tendency from lately acquired monoecism toward direcism as 

 shown by the fact that staminate and pistillate flowers are pro- 

 duced several days apart, thus inviting cross-fertilization be- 

 tweeen individuals. 



The University of N^ebraska. 



ALFILAKIA T^t ARIZOTs^A. 



Perhaps the most abundant and wide-spread of the intro- 

 duced species that have become naturalized in the southwest is 

 the interesting plant alfilaria, ErodiiDii cicutarium , a near rela- 

 tive of the geraniums of woods and gardens. Tn common with 

 a number of other annual plants indigenous to the Mediterranean 



