62 
AMERICAN JOURNAL OF BOTANY 
[Vol. io, 
removed and placed on the same medium which gave good germination for 
the pollen of normally dehiscing stamens. There were many anthers that 
were partly dehiscent, that is, they opened to some extent, and the pollen 
thus shed was often viable in tests and productive of seed in controlled 
pollinations. 
As a rule, the loss of sex for individual flowers was one-sided. When 
the pistil was rudimentary the stamens tended to be well developed as at 
c, figure 2. When the stamens were aborted the pistil was usually of good 
size as at c, figure 4. Occasionally, however, the pistil in flowers with 
aborted stamens was undersized as at d, figure 4, but cases of complete or 
extreme abortion of all stamens and of the pistil in the same flower were 
not observed. 
The entire lot of plants were grown throughout under very uniform 
conditions which favored continued vegetative vigor, and only one genera¬ 
tion has been critically studied. Development under conditions which 
affect differently the vegetative vigor and the length of the growing period 
may influence and possibly decidedly change the behavior in respect to 
cyclic changes, quite as such conditions are known to affect the sex of certain 
plants, particularly of A risaema triphyllum (Pickett, 1915; Schaffner, 1922), 
from year to year. Definite evidence regarding the direct or indirect 
influences of environment and the somewhat synchronous changes of sex in 
the spider flower remains to be obtained. 
At the close of the season, when the vigor of plants perceptibly wanes, 
all parts of the flower, corolla, pistils, and stamens alike, are uniformly 
undersized. Whether the last flowers that are produced on a plant that 
reaches old age before being killed by freezing temperatures are as a rule 
predominantly pistillate or staminate was not determined with certainty. 
On many such plants the last flowers were decidedly weak in maleness, but 
for other plants such flowers were decidedly male or bisexual. 
Summary 
In the cultures of Cleome spinosa grown for this observational study 
there was wide variation in the morphological character of the flowers in 
regard to the relative development of the two kinds of sex organs. The 
entire range of variations was seen among the flowers of a single plant, 
giving bisexual flowers, flowers that were functional only as males or as 
females, and many intergrading types. The variation from one extreme to 
the other was repeatedly cyclic, which condition results in the intermittent 
production of fruit. 
All of the 128 plants grown under special observation were quite similar; 
all exhibited the extreme ranges of flower forms or intersexes; in all the 
production of fruit was more or less intermittent; none was exclusively 
staminate or pistillate. 
