AMERICAN 
JOURNAL OF BOTANY 
Vol. X February, 1923 No. 2 
ALTERNATION OF SEXES AND INTERMITTENT 
PRODUCTION OF FRUIT IN THE SPIDER 
FLOWER (CLEOME SPINOSAy 
A. B. Stout 
(Received for publication April 6, 1922) 
Irregularities in the formation of reproductive organs, such as are seen 
in the phenomena of intersexualism in both plants and animals, have two 
points of special interest. First, they involve a particular type of sterility 
of various grades and degrees of expression, which in plants often affects 
the production of fruit and seeds and becomes a matter of practical im¬ 
portance in respect to crop production and in the breeding of various 
economic plants. A second point of interest is in the bearing which the 
phenomena of intersexualism have on questions of sex differentiation, the 
alternation of sex, and the evolutionary tendencies in reproduction. 
In its general significance, several points regarding sterility from inter¬ 
sexualism are clear. In plants it tends to the alternative development of 
one or the other kind of sex organs, giving, in comparison to the fundamental 
condition of hermaphroditism, a one-sided sterility. There is incomplete 
development or abortion of one or the other of the sex organs which is 
discriminating and which results in alternative development, with, however, 
many grades in the relative development. Thus, in plants, the so-called 
“sterile” intersexes are, in general, individuals that are predominantly male 
and often highly functional as such. These individuals are sterile only in 
the sense that they are fruitless. Also the so-called ‘‘ self-sterile ’ ’ individuals 
and varieties of plants, as is well shown in the cultivated grapes in which 
sterility from intersexualism is well marked, are predominantly female and 
able to function feebly or not at all as males. They are productive of fruit 
only when properly pollinated from male or hermaphroditic individuals. 
Very seldom, if ever, is complete sexual impotence for a plant as a whole 
seen as a condition of intersexualism, as is frequently the case in sterility 
from hybridity. 
But in many cases of intersexualism in animals, to which attention has 
recently been especially directed, the complete sterility of individuals is 
very frequent. Here, however, the condition arises in dioecious forms and 
involves the partial change of an organ from one sex to the other after 
1 Contribution from the New York Botanical Garden, No. 239. 
[The Journal for January (10 : 1-56) was issued February 3, 1923]. 
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