It is so little known, however, that it can hardly be said to have a common name.

Most mountaineers refer to it as "that queer little pine-tree covered all over with burs." In my studies of this species I found a very interesting and significant group of facts, whose relations will be seen almost as soon as stated: 1st.

All the trees in the groves I examined, however unequal in size, are of the same age.
2d.

Those groves are all planted on dry hillsides covered with chaparral, and therefore are liable to be swept by fire.
3d.

There are no seedlings or saplings in or about the living groves, but there is always a fine, hopeful crop springing up on the ground once occupied by any grove that has been destroyed by the burning of the chaparral.
4th.