1901] Rehder, — Notes on Hybrids of Quercus ilicifolia 137 
result of a coccoid stage than produced by true sporangia. The 
appearance of P. crepidinum is much that of a Dermocarpa, but the 
true vegetative cell divisions place it in Pleurocapsa. 
It occurred sparingly in a coating composed of several minute 
algae, on the woodwork of an old wharf, at Otter Creek, Mount 
Desert, Maine, July 17, 1900. 
Protoderma marinum was included in the Preliminary List published 
in RHODORA, Vol. II, p.45 : Ectocarpus fasciculatus var. abbreviatus, 
Jsactis centrifuga, Elachista Chondri, and Actinococcus aggregatus were 
issued in the Phycotheca Boreali-Americana, Nos. 731, 757, 773 
and 786, respectively; Je/obesia Cora//inae wil appear in a later 
fascicle. 
NOTES ON HYBRIDS OF QUERCUS ILICIFOLIA. 
ALFRED REHDER. 
WHILE botanizing last year about the middle of September in 
the Blue Hill Reservation and following the path which leads 
from Blue Hill Avenue to the top of the hill, I directed my atten- 
tion to the varying shapes of the foliage of the Oaks. Quercus 
rubra, coccinea, velutina, alba, Hicifolia and prinoides are common 
there, with the exception of the last named species, and form, in fact, 
the chief components of the second growth which clothes the hill. 
The top is almost exclusively covered by the low growth of Quercus 
ilicifolia, hardly exceeding 5 ft. in height. As I reached this region 
and was passing the last higher bushes of Quercus coccinea and some 
other trees, my attention was attracted by a small tree bearing 
foliage similar in shape to that of Quercus ilicifolia but differing in 
habit and greater height from this species. The leaves, too, although 
they had almost the outline of those of Quercus ilicifolia showed a 
marked difference in the tomentum of the lower surface, which was 
only slightly tomentose or almost glabrous in most of the leaves. 
These characters led me at once to the conclusion that I had 
stumbled on a hybrid of Quercus ilicifolia with a species of the Q. 
rubra group and I naturally suspected first Q. coccinea, which grew 
plentifully around it, to be the other parent. A closer examination, 
