H. Stuart Thompson. 15 1 
develop much later, it is possible that conditions accelerating or 
retarding the development of catkin buds may influence the pro¬ 
portions of the two kinds. 
Variations similar to those above recorded for Myrica Gale 
are described by Chevalier as occurring to a marked extent for 
certain monoecious species of Myrica (notably M. calipornica, 
M. conifera and M. pubescens), in which a polygamous condition 
obtains. Chevalier suggests nutrition as the factor which controls 
the distribution of the sexes on monoecious individuals in any one 
season, as well as the changes taking place in different seasons. 
In conclusion, our thanks are due to Dr. E. N. Thomas for 
encouragement and helpful criticism. 
Botanical Research Laboratory, 
University College. 
DESCRIPTION OF PHOTOGRAPHS ON PLATE I. 
1. Different kinds of flowering shoots (April, 1913), a, b, c, d, reading 
from left to right. 
a. Branch with staminate catkins, showing remains of small amount 
of fruit of previous years. 
b. Branch with remains of fruiting catkins (1912) bearing one 
staminate and two pistillate shoots. 
c. Branch terminated by fruiting shoot of 1912, below which have 
arisen shoots bearing staminate and “ hermaphrodite ’ ’catkins 
d. Is entirely pistillate, with remains of previous season’s fruiting 
catkins. 
2. Fruiting, branch in August, bearing a shoot with young staminate 
catkins for next season. 
3. Branch bearing staminate catkins on 1915 shoots. On the left is a 
bare persistent staminate shoot of the previous season, and on the right a 
fruiting shoot showing woody axes of catkins and bracts persisting after the fruit 
has been shed. 
RADICAL LEAVES OP PARNASSIA PALUSTRIS 
AND VALERIANA DIOICA. 
By H. Stuart Thompson, F.L.S. 
[With Two Figures in the Text]. 
C ONFUSION may possibly occur between young plants of these 
two species (which often grow in the same habitat) owing to 
the superficial similarity of their radical leaves. The writer fell 
into this mistake two years ago, believing he had gathered the 
former plant, which had not been recorded from Somerset since 
