164 
sheath fall off and a terminal scar is left (Fig. B). Both stages 
were visible during the first week of August. The uppermost sub- 
petiolar bud continues the growth of the branch; this is, however, 
an axillary bud. It does not become visible until the leaves of 
that part of the stem which remains have fallen off. 
Corylus Americana (Fig. 15) casts off its tips while they are 
still small. One of these tips is here figured. The axillary scaly 
buds are small and oval or rounded, showing but three or four 
scales exteriorly; the base of the leaves is distinctly and strongly 
heart shaped. Ostrya Virginica (Fig. 16) has long, pointed axil- 
lary scaly buds, showing six or more scales exteriorly. The peti- 
oles about equal the buds in length. The lower half of the leaves 
is wedge-shaped, with a narrow base. The tip of the leaves is 
long, almost awl-pointed. Carpinus Virginiana (Fig. 17) has 
ovate obtuse scaly axillary buds. The petiole of the leaves is 
more than three times as long as the subtended scaly buds. The 
lower half of the leaves is much less evidently wedge-shaped, and 
the base is more rounded than in the last species. The short, 
almost abruptly pointed tip of the leaves is quite a useful distin- 
guishing feature. In all three species just enumerated, the termi- 
nal scar is very tiny, and often difficult to find. Their leaves are 
alternate, and distichous. In the scaly buds this phyllotaxy is ob- 
scured by the fact that most of the scales represent stipules, and 
hence occur in pairs; on this account the distichous arrangement 
of the elements of the bud cannot be readily made’ out. This 
characteristic will serve to distinguish these genera from the or- 
dinary distichous plants during winter months. Species of Quercus, 
Castanea and Fagus show terminal scaly buds. 
Some species of Sa/ix show terminal scars (Fig. 13) | Observed 
species of Populus have terminal scaly buds. 
Some species of Svzz/ax show at times a short shriveled up rem- 
nant of the tip of the branches, at others a terminal scar (Fig. 23). 
The best cases of groups of plants casting off the tips of their 
branches quite generally are the Leguminosz, Urticacez, the Car- 
pineze among Cupuliferz, perhaps the Bignoniacez, and to a lesser © 
degree the genera Zilia, Staphylea and Aesculus, the sections Su- 
mac and Lobadium of Rhus, possibly the Vitacez in part, and ap- 
parently a fair proportion of the species of the genus Sa/zx. 
