267 
On the Casting-Off of the Tips of Branches of Certain 
Trees. 
By Aue. F, FOERSTE. 
(PLaTE CXXXII.) 
The growth of the branches of trees for each year ceases at 
widely different periods. Some trees continue growth until they 
are “killed back” by the early frosts of autumn. Others develop 
terminal scaly buds, often quite early in spring, and thus have 
the extent of their growth determined long before extraneous 
Causes tend to check their development. The time at which ter- 
minal buds are formed varies widely in different species, but it is 
well known that before the end of May most trees have terminated 
the yearly growth of their branches in this way. A small percent- 
age of our trees have, however, developed the curious habit of se- 
curing determinate growth, by casting off the tips of their branches 
at well formed joints. Thescarsleftat these joints are usually smooth, 
and may r eadily be distinguished from leaf-scars by the fact that 
the fibro-vascular tissues do not form bundles, and appear as 
little protuberances in the scar, as is the case with most leaf-scars. 
Instead, the fibro-vascular tissues form a more or less circular 
figure, following the outline of the scar, as might be expected, 
since they represent the fibro-vascular tissues between the wood- 
layers and the bark proper. In Catalpa speciosa, Warder, this 
terminal scar may be seen on the lower sides of the branches 
(Fig. 2). The leaf-scars and the corresponding leaves are usually 
smaller here than on the upper side of the branch (Fig. 1) on the 
More mature twigs, although the leaves of each whorl are all 
similar during their early history. Staphylea trifolia, Linn. showsa 
terminal scar (Fig, 3), in some cases almost hidden between the 
two upper lateral buds. Ad/anthus glandulosus, Desf. also has a 
terminal scar (Fig. 5). An the branches of the same tree = 
not cast off their tips, even in cases where part of the branc es 
may almost invariably be expected to have done so. ae is 
well shown by various species of Asculus for instance, @scu/us 
ff ippocastanum, Linn., where a part of the tips have been cast off, 
leaving exceedingly well-marked and evident terminal scars Sigel 
4), whereas almost all twigs of less vigorous growth, and some o 
