Page:Popular Science Monthly Volume 86.djvu/43

Rh over trunks and branches clear to the tops of the trees. Other species hang from the trees and lianes in festoons a yard or two in length.

The seed plants also of this rain forest show the same diversity of habit. There are dozens of climbers and twiners, such as Bidens, Marcgravia, Sciadophyllum and Rhynchosia, which cling to the trunks of the larger trees and so make their way up to the light. The Marcgravia is especially interesting from its possession of honey cups, which tempt the humming-birds that accomplish the pollination of its simple, inconspicuous flowers. Scores of bromeliads and orchids, as well as the ferns mentioned above, have become air plants, entirely without any connection with the ground. These epiphytes collect water and the solid food needed either from material falling into their cup-like leaf clusters, or absorb them as they drip down over the bark of the supporting tree. Indeed, trees of some size may find the necessary soil and water in the turfs of smaller air plants and the débris accumulated by them, even forty or fifty feet from the ground on the limbs of a big Podocarpus. The very leaves of trees, shrubs and of the more persistent herbaceous plants may become covered with epiphytic lichens and liverworts. In all these cases the air plants are not parasites, but simply use the trunk, branch or leaf as a standing place in which adequate light is available. In the lowlands we saw certain of these air plants actually flourishing on telephone wires.

If we go northward from Morce's Gap and down 2,000 feet into the