1880.] Supposed Dimorphism of Lithospermum longiflorum. 417 
THE SUPPOSED DIMORPHISM OF LITHOSPERMUM 
LONGIFLORUM. 
(in ANGUSTIFOLIUM MICHX. OF GRAY’S SYNOPTICAL FLORA.) 
BY PROF. C. E. BESSEY, M.SC., PH.D. ieee 
de plant under consideration is a common herbaceous per- 
ennial of the prairies and great plains of North America. In 
the latter part of April and during the month of May it produces 
flowers with bright yellow salver-shaped (Aypocraterimorphous) 
corollas, whose tubes are about thirty mm. (one and one-fifth 
inch) long, and from two to three mm. in diameter. About the 
first of June, in Central Iowa, these large flowers suddenly dis- 
appear, and from this time forward until the autumn frosts, they 
produce only small cleistogamous flowers! The corolla lobes of 
the latter cohere somewhat, and remain closed, and in this condi- ` 
tion the total length of the corolla is from five to seven mm., the 
tube itself being no more than three to five mm. long. Both 
kinds of flowers produce seeds, and I have not ohserved any dif- 
ference in their relative fertility, although there are actually at 
least ten times as many seeds produced during the season by the 
smail flowers as by the large ones, for the reason, however, that 
there are many more of the former flowers than of the latter. Of 
the small flowers I will have somewhat to say at another time ; 
what I wish particularly to notice at this time is the relative posi- 
tion of stamens and stigma in the large early flowers. 
An examination of a number of flowers shows that in some 
the anthers are higher than the stigma, while in others they are 
lower, and unless careful measurements are made, one is led to 
consider this as a case of dimorphism of the sexual organs (the 
heterogonous dimorphism of Dr. Gray, and heterostyly of Hilde- 
brand, Darwin and others), a supposition which is rendered still 
more probable by the well-marked dimorphism of the flowers of 
the nearly allied Lithospermum canescens Lehm. However, after 
making a large number of very careful measurements, I have no 
hesitation in saying that in the plants a3 they occur in Central 
Iowa there is no dimorphism whatever, but that we have here a 
case of great and irregular variability in the length of the style 
and of the corolla tube, and that upon the varying length of the 
latter depends the varying position of the stamens. 
In the following table the flowers of the first ten plants were 
Measured May 4, 1878; those of the next five, May 19, 1877; 
and those of the remaining three, May 26, 1877. 
‘First noticed by M, S. Bebb. See AMERICAN NATURALIST, Vol. VII, p. 691. 
