38 THE JOURNAL OF BOTANY 
than is obur, arose from lanuginosa at a comparatively 
recent date; and that Q. Robur, in its turn, sprang from Q. sessili- 
flora distribution of @. lanuginosa suggests that it may be 
off as a semiglabrous mutant of Q. lanuginosa, and Q. Robur 
s a glabrous mutant of Q. sessiliflora. The floral battle 
subspherical acorns of one form of Q. sessiliflora, appear to be 
of atu i er 
ors ; whilst other characters, such as the leaf-auricles of Q. Robur, 
and the subspherical shape of the acorns of one of the varieties 
Key To THE Britisn Oaks. 
The following key will be useful in determining the species of 
Oak likely to be met with in the natural or semi-natural woods of 
the British Isles :— ; 
A.—Fruit taking two summer seasons to ma- 
ture. Cupules “mossy.” Terminal buds 
with many long filamentous scales. Leaves 
with multiple hairs. . : . : : 
B.—Fruit ripening in a single season. Cupules 
ves glabrous or not 
(a) Leaves with multple hairs on the 
| icles 
1. Q. Cerris. 
a. Young twigs, petioles, bud-scales, 
—. leaves with multiple hairs. . 2. Q. lanuginosa. 
s 
or almost glabrous. Leaves with 
multiple hairs, which, however, 
3. Q. sessiliflora. 
ei : , : . 4. Q. Robur. 
(c) Leaves bi-auriculate. Multiple hairs ee 
present. . ‘ : - 0. Q. Robur x sessiliflora. 
may be very small... . : 
(2) “pete bi-auriculate. Multiple hairs 
a 
