152 Rhodora [AvavsT 
"They are, of course, of all degrees of perfection, from loose aggregations 
of miscellaneous materials, familiar enough on all beaches and attract- 
ing no notice, up to those perfectly rounded forms whose symmetry 
and smoothness of outline compel attention and demand explanation; 
and it is these more perfect forms which are the subject of these two 
articles. Probably they occur, in suitable places, all over the globe, 
and, after all, the most curious thing about them is the fact that they 
are seemingly so little known, and so rarely mentioned, in botanical 
literature. 
Smita CoLLEGE, Northampton, Mass. 
A COLOR FORM OF POTENTILLA PUMILA. 
C. A. WEATHERBY. 
THERE is a place in the outskirts of Cambridge which, partly be- 
cause of its interesting indigenous plants and partly because of certain 
dumping grounds in its vicinity, well repays the botanist for an occa- 
sional inspection. In the course of a recent visit to this spot, Professor 
Fernald and the writer noticed a peculiar and very pretty Potentilla, 
which, on examination, proved to be a form of P. pumila Poir. with 
cream-colored petals. ‘There were forty or fifty vigorous plants of it, 
chiefly in a dense central colony, but with outlying individuals scattered 
over a space some fifty feet in diameter. With their pale petals, they 
contrasted strongly with the typical Potentilla pumila which grew 
abundantly about and intermingled with them. No intergradients 
between the two forms were observed. 
The pale-flowered plant differs from typical material of P. pumila 
only in the color of its petals. It apparently represents a variation 
analogous to the color forms of Gratiola aurea recently described by 
Mr. H. H. Bartlett in Кнорока [9: 122]. No white-flowered Poten- 
tilla pumila to correspond with Mr. Bartlett’s forma /eucantha has, 
indeed, been recorded, so far as the present writer is aware; but the 
color-relation between typical P. pumila and its pale-flowered variant 
and that between Gratiola aurea and its forma helveola are rather 
strikingly similar. 
