1920] Grier,—Equisetum sylvaticum 165 
that Prof. Wiegand does not seem to have been able to discover 
material of Clayton's 162. 
In any event, as has often been pointed out (S. F. Blake, Rno- 
DORA 20: 21), one is not justified in laying stress on a specimen preserved 
in an old herbarium and taking it as the type of a species, unless it 
agrees with the diagnosis of the species given by the author. In the 
present case as the specimen preserved does not accord with the 
description I think it should not govern and as the description does 
exactly answer a plant now known from Virginia I think it should 
be applied to it. 
In conclusion then I would use the following names: 
(1) Species No. 1. Eupatorium purpureum L. 
(2) Species No. 2. Eupatorium Bruneri A. Gray (probably) 
(3) Species No. 3. Eupatorium maculatum L. 
(4) Species No. 4. Eupatorium trifoliatum L. (provisionally) 
New York Crry. 
LIGHT CORRELATED VARIATIONS OF THE STERILE 
STEM OF EQUISETUM SYLVATICUM. 
N. M. Grier, Pu. D. 
A FAIRLY abundant growth of Equisetum sylvaticum L. was ob- 
served at Bellevue, Pennsylvania. One section of the growth was 
constantly well shaded, while the other had the benefit of sunlight 
throughout the day. In corroboration of the differences appearing 
at first sight between the plants of these two sections, one hundred 
plants from each were collected and the following tabulations made. 
NUMBER OF ESTIMATED WHORLS PER PLANT 
A CU PORE 78 910 141 RG M. 15 
SDN LES qoe 5 4 14 25 23 15 12 
Ed coo ORAN 12 3 8 19 29 99 "99 
A conclusion derived from the above is that plants of this species 
growing in the sun have on the average a larger number of whorls 
