DL BROOKLYN BOTANIC GARDEN MEMOIRS 
summer, when compared from year to year, are as exact in relation to 
time and energy expenditure as are the flowering periods. Thus, if 
we compare the vegetative growth of the Yellow Adder’s Tongue during 
1913 with that of the present year the tips of the leaves were simul- 
taneously emerging from the ground over wide areas of a valley on 
March 27, while this year they appeared on the 11th of April. In 
both cases these leaves were 23 inches high 3 days thereafter, and so 
comparatively suddenly transformed wide woodland areas from a 
bare unclothed aspect into rich showy brown-green verdure. 
If we consider now a few naked eye details that depend on definite 
histological changes, it may be said that botanists are aware that for 
any given species of shrub or tree a fairly definite period arrives 
when easing and separation of the epidermis along the stem is effected, 
after cork formation has replaced it functionally. Some species show 
this change in the latter part of the first year, many in the early part 
of the second, while others may be delayed until the following autumn 
or even later. A more pronounced though related occurrence is seen 
annually in the oriental plane. The extensive flakes of old dull-gray 
cork start to separate synchronously on the average about June 28 
and so reveal the white younger cork underneath with increasing 
effect during the next few days, but variation as to date of this event 
may occur from year to year according to environal stimuli. Oppor- 
tunity has twice occurred for comparing this with the behavior of the 
same species round Kew Gardens, England, and there a like change 
starts on July 29. This comparative result agrees closely with other 
data obtained as to floral maturation. 
Closely related again to the above studies is one that has scarcely 
been touched in this country, but which has been investigated by 
Hoffmann-Ihne in their observations at Giessen. This is an exact 
comparison of flowering periods according to longitude and latitude, 
particularly the former. Exceptional facilities exist for the prose- 
cution of such an inquiry in this country, for were thirty or forty 
observational stations established under competent workers, and the 
whole correlated at a central office, valuable results would accrue after 
a period of ten to twelve years. A feature of interest here is that a 
considerable number of plants of the eastern seaboard extend their 
range from central or northern Florida to Newfoundland or even 
Labrador. One of these which the writer has shortly referred to 
elsewhere’ is our native pitcher plant (Sarracenia purpurea). In 
northern Florida, as for example round Ponce de Leon, it starts to 
bloom in the last week of March and continues until April 10. In the 
Charleston region, as at Summerville, it is averagely five days later; 
4 Engler’s Pflanzenreich, vol. 4 (1908), p. 23. 
