these mountains, I
could, after examining a few of the trees around me, tell the points
of the compass, the altitude above sea-level, and the season of
the year.

[Illustration: ASPENS]

At an altitude of about sixty-five hundred feet cottonwood, which has
accompanied the streams from the foothills, begins to be displaced by
aspen. The aspen (_Populus tremuloides_) is found growing in
groups and groves from this altitude up to timber-line, usually in the
moister places. To me the aspen is almost a classic tree, and I have
met it in so many places that I regard it almost as an old friend. It
probably rivals the juniper in being the most widely distributed tree
on the North American continent. It also vies with the lodge-pole pine
in quickness of taking possession of burned-over areas. Let a moist
place be burned over and the aspen will quickly take possession, and
soon establish conditions which will allow conifers to return. This
the conifers do, and in a very short time smother the aspens that made
it possible for them to start in life. The good nursery work of aspens
is restricted pretty closely to damp places.

Besides being a useful tree, the bare-legged little aspen with its
restless and childlike ways is a tree that it is good to know. When
alone, these little trees seem lonely and sometimes to tremble as
though just a little afraid in this big strange world. But generally
the aspen is not alone. Usually you find a number of little aspens
playing together, with their leaves shaking, jostling, and
jumping,--moving all the time. If you go near a group and stop to
watch them, they may, for an instant, pause to glance at you, then
turn to romp more merrily than before. And they have other childlike
ways besides bare legs and activity. On some summer day, if you wish
to find these little trees, look for them where you would for your own
child,--wading the muddiest place to be found. They like to play in
the swamps, and may often be seen in a line alongside a brook with
toes in the water, as though looking for the deepest place before
wading in.

One day I came across a party of merry little aspens who were in a
circle around a grand old pine, as though using the pine for a maypole
to dance around. It was in autumn, and each little aspen wore its
gayest colors. Some were in gowns of new-made cloth-of-gold. The
grizzled old pine, like an old man in the autumn of his life, looked
down as though honored and pleased