154 Scientific Intelligence. 
The winter buds give characters in some species. Ag to the 
shape of the leaves, so extremely variable, it is remarked, “that 
those oaks, which in the perfect state have deeply lobed or pinnati- 
fid leaves, show in young shoots and on adventitious branchlets 
less divided or even entire leaves; while, singularly enough, the 
oaks whose leaves in the adult tree are entire, or nearly so, often 
eaves.” 
The vernation of the leaves, although more commonly condupli- 
cate, both in white and black oaks, furnishes other types, which 
Dr. Engelmann has first brought into prominent view, and finds 
of great account in distinguishing allied species and doubtful vari- 
eties, and in unravelling intricate questions of hybridity or affinity. 
The nature of the down on young leaves may also be turned to use. 
The venation occasionally enables easily confounded species, such 
as Q. agrifolia and Q. Wislizeni, to be distinguished even in ster- 
The persistence of the leaves is a good character in some species, 
while in others it is of no account. The leaves of some oaks per- 
sist even to the third year, “ Only such oaks ought to be called 
evergreen which retain the greater part of their old leaves, at least 
until the new ones are fully grown.” 
In the male flowers the size and number of the anthers furnish 
good distinctions, being small and mostly 5 to 10 in the white 
oaks, four or sometimes 5 to 6 and larger in the black oaks; the 
S var several, male flowers distinguish 
the principal groups, especially the styles, which in the white 
oaks are ses i 
the shell is thicker and lined with a silky down. 
All these matters relate to the true oaks (section Lepidobalanus), 
with scaly acorn-cups, pendulous male catkins wholly apart 
the solitary or distant female flowers. But in California we have, 
m Q. densiflora a representative of the otherwise Asiatic sub- 
tkins, linear pointed stigmas, and a spinose cup, which, how- 
is ba of an oak rather than like the prickly involucre of the 
eatheut, 
The paper continues with a systematic enumeration of the 38 
recognized species, and notes are appended to about half of them. 
5 bess 
