192 . Rhodora [SEPTEMBER 
A DIMORPHISM IN TIARELLA CORDIFOLIA. 
C. H. DANFORTH. 
TEN years ago while botanizing in Norway, Maine, the writer was 
surprised to find two sorts of anthers in Tiarella cordifolia. It was 
noticed at the time that in all the fresh flowers on some plants the 
anthers were bright yellow while in others they were all of a decided 
orange color. The two types were quite distinct in this one particu- 
lar, but apparently identical in every. other. 
Since 1901 I have regularly observed both forms at Norway, but 
no further study of them was made until the present season when I 
examined the anthers and pollen microscopically. The color of the 
anthers was then found to be due largely or entirely to the contained 
pollen. The dry pollen grains are elliptical in outline. Those from 
the yellow anthers are of a clear yellowish green color, those from the 
orange anthers have a reddish brown tint. When placed in water 
or weak alcohol they become shorter and somewhat triangular. In 
a few moments, especially in the alcohol, small droplets of the coloring 
matter are forced through the wall and collect on the surface giving 
the grain a tuberculated appearance. The orange pigment is in 
relatively greater abundance and is more noticeable than the yellow. 
It is not dissolved by water or weak alcohol, in which the droplets 
tend to coalesce, but it does mix freely with ether, chloroform, xylol, 
and strong alcohol. 
The anthers retain their color, at least for a time, in pressed plants 
but in old herbarium material they are badly faded, due it may be to 
the poisoning agents that have been used. Recently, however, I 
have received fresh specimens of both forms from Caribou, Maine, 
Bridgewater, New Hampshire, and Barre, Vermont, which indicates 
that the variation is of widespread occurrence. The relative abun- 
dance of the two forms has not been determined, but it is a personal 
impression that they are in the proportion of at least two plants with 
yellow anthers to one with orange. 
No traces of mycelium or other evidences of pathological change 
could be detected in fresh mounts, and both kinds of pollen readily 
germinated under artificial conditions producing good tubes. ‘Thus 
it seems very probable that we here have to do with normal plants 
