Page:Popular Science Monthly Volume 26.djvu/701

Rh adaptation. The leaves of the Bryophyllum appear folded in the sun, spread out flat in the shade; and the same phenomenon was observed in a modified form in the very abundant Psidium Guava and some other species. Other plants form close and hard cuticles which restrict evaporation, and some others appear to be furnished with special water vessels in their hypodermic layers. To this class seem to belong the thick-leaved calabash-trees and shore-grapes, and the creeping Commelyaceæ.

From admiring a number of highly colored flowers, our attention was drawn to the modest sensitive-plant (Mimosa pudica), which. was here growing in masses as a common weed alongside of the cultivated fields. A goat was feeding along the hedge-side, and had stretched out his tongue toward the delicate mimosa-leaves, but had not reached them, when he suddenly drew his head back in astonishment at the strange sight of an array of sharp thorns, forbidding closer approach, where he had only an instant before anticipated the taste of a mouthful of delicious foliage. The mimosa thus protects itself against the unwelcome feeder upon it in the same manner as the hedgehog escapes his enemies by rolling himself up into a prickly ball. Now was explained to us the observation we had made before in the country, of islands of mimosa-plants rising untouched from the pastures in which all the other plants around them had been closely eaten away. The same property of withdrawing itself from unfriendly contact operates to protect the mimosa against injury from wind and rain.

As we go up the mountain-walled valley of the Roseau, in the intervals of which cultivation still presses hard upon the primitive vegetation, we admire the variety and brilliancy of the extra-floral display by which some of the species are made conspicuous, and which is one of the marked features of the West Indian flora. Here is a begonia, with rose-red peduncles; there are some bromelias, with brightly colored bracts attached to their flower-stocks. The Heliconia, or wild-banana, is marked from afar off not more by its enormous leaves than by the brilliant purple spathe that surrounds its unobtrusive inflorescence; and the Euphorhia heterophylla is equally distinguishable by the patches of crimson on the whorl of leaves nearest to its flowers; while many other plants have their real leaves variegated with stripes or spots of color. Of most graceful and noble bearing are a group of tree-ferns, the unapproachable delicacy of whose leaf-carving, the remarkable harmonizing of the green of their foliage with the dark brown of their stems, and the perfect symmetry and pose of their crowns, are worthy of and receive the highest admiration. As we continue the ascent, the wood becomes largely composed of the Bursera gummifera, a tree of the terebinth family, the magnificent stems of which are supported by wide-spreading pillar-roots and varnished with the white balsam that has exuded from their bark. Moss-like plants nestle under the shelter of the root-pillars, lianas climb around the