the South, shed their leaves every fall, like other common decid- 
uous trees. Even the so-called “evergreen” trees do not retain 
their leaves throughout life, but shed them after some years, vary- 
ing from three or four in the pine to ten or twelve in the spruce. 
The question as to the length of time the old leaves hang on the 
trees makes a very interesting one for study. It can usually be 
answered quite readily by noting on the twigs the successive 
scars of the old bud-scales, the portion of the stem between any 
two successive rings of bud-scale scars, of course, constituting 
one year’s growth. 
The needle-shaped leaves of the pines and spruces, and the 
flat, scale-like leaves of the arbor vitae and white cedar are not 
often associated by the majority of people with the broad leaves 
of the common hard-wood trees. Yet they are true foliage leaves, 
and do the same work as other foliage leaves. Their stiff, rigid 
shape and their general structure show that they are admirably 
adapted to resist very trying climatic conditions, such as 
drought and severe cold. For this reason, the conifers are the 
most successful trees of the the cold north and of mountain tops. 
Another interesting fact to which attention may be called 
is that the leaves of pines and other conifers, on young or 
“juvenile” plants, are very different from those on mature spec- 
imens. In the case of pine seedlings, for example, the leaves 
produced the first year, and for several years thereafter, are 
borne singly, arising directly from the main stem instead of in 
little groups from short, lateral spur shoots, as they are in later 
stages. These so-called primary, or juvenile, leaves of the pine, 
arising directly from the main axis, are really of the same 
structural value as (i. e. homologous to) the scales spoken of 
above, which subtend the spur shoots. While ordinarily, in older 
stages of the red cedar and arbor vitae, very small, awl-shaped 
leaves are found, appressed close to the stem, still one often 
finds juvenile forms of these same species, on which occurs an 
entirely different sort of leaf, needle-shaped, and spreading away 
from the stem. Thus we find illustrated among plants a phenom- 
enon quite similar to that among men, indicated by the expres- 
sions, “an old young man,” and “a young old man,” the juvenile 
forms of these trees corresponding to the latter. 
Some search will, in fact, often reveal juvenile forms of leaves 
even on certain branches of quite old plants. Some of our Garden 
junipers, on the north shore of the lake, near the outlet, and 
other conifers show this phenomenon very clearly. 
The following key, based entirely on leaf characters, may be 
used for identification of the more common representatives of the 
genera of conifers found growing in the Botanic Garden, and 
in the parks and lawns about Brooklyn. 
E. W. O. 
