76 
AMERICAN JOURNAL OF BOTANY 
[Vol. 9 
be no special difficulty in determining the exact environmental factor or 
group of factors which determine maleness or femaleness in the incipient 
inflorescence bud. 
Arisaema dracontium 
Some work has been done on Arisaema Dracontium both experimentally 
and in the field, although it is much less common around Columbus than 
A. triphyllum. In this species, so far as the writer's knowledge goes, there 
are staminate and monoecious individuals. No pure carpellate plants have 
been discovered, although there are decided differences in the relative 
widths of the carpellate and staminate zone between different monoecious 
individuals. One plant was found that came very near to a pure carpellate 
inflorescence. The normal part of the flower-bearing spadix was purely 
carpellate, but on the sterile part above this there were six scattered stami- 
nate and imperfectly staminate flowers. One of these flowers was half 
carpellate. It is probable that in rare instances pure carpellate inflores- 
cences are produced. One "staminate intermediate" plant was found 
having three carpellate flowers on one side at the base of the inflorescence, 
which was otherwise normally staminate; another staminate plant had two 
carpellate flowers near the middle of the spadix on opposite sides. Such 
intermediate staminate plants, even though they have the abnormal 
carpellate flowers fertilized, soon wither like ordinary staminate peduncles 
as in similar cases in A. triphyllum. Abnormal monoecious individuals 
were also found. One of these had two staminate flowers at the base, then 
a zone about one fourth inch wide of carpellate flowers, and above this a 
zone three fourths inch wide of staminate flowers; another had a single 
carpellate flower in the middle of the staminate zone; another was nearly 
completely staminate at the base, but in this there were three carpellate 
flowers, next there was a complete narrow zone of carpellate flowers, and 
above a wide zone of staminate flowers again. Three other monoecious 
inflorescences had each several staminate flowers at the base of the carpel- 
late zone. One monoecious plant had the lower part in irregular staminate 
and carpellate patches. In those inflorescences which have staminate and 
carpellate flowers in patches, as well as in the ordinary monoecious type, 
there is often a general confusion of floral structures, as reported by the 
writer (6) for A. triphyllum. There are flowers partly staminate and partly 
carpellate, staminate flowers whose stamens have stigmas, and neutral or 
partly neutral structures of various abnormal shapes. These examples show 
that, as in A. triphyllum, there are intermediate individuals which do not 
have the ordinary types of sexual expression. 
A statistical study of two habitats for two years gave the results shown 
in table 2. 
The plants in the second habitat (III and IV) are apparently dying 
out rapidly because of changing ecological conditions and the ravages of 
