Page:Popular Science Monthly Volume 26.djvu/698

680 from the west coast, passes through cultivated and half-tilled lands into a romantic river-valley, and then through the primitive wilderness over hills and mountain-torrents, into an upland valley about three thousand feet above the sea, in the bottom of which lies the boiling lake, surrounded by a grim waste of volcanic rocks.

The starting-place for our excursion is the little town of Roseau, the chief place of the island, and the only one where the traveler will find a boarding-house, situated on the west coast, picturesquely set down at the mouth of a romantic valley, among sugar-cane fields and palm-gardens, and framed by forest-covered mountains. Before starting on our excursion we will make a short study of the shore, a flat beach of sand and gravel, sunny, hot, and dry, but which supports a characteristic vegetation. We are struck, in looking at this beach flora, with the predominance of the creeping plants, by which the most diversified botanical families are represented. Their habit of growth, with the multitude of rooting points it permits, gives them great advantages in keeping their hold on the shifting sands, and access to numerous points at which they may tap the soil for its scanty supplies of moisture. The succulent nature of the organs is another peculiarity of these plants that will strike the Northern observer. Most of them, whether they be creepers or upright, are either provided with fleshy leaves, or consist of amorphous thick stems without expanded foliage. This property, which must be regarded as a provision to diminish transpiration, is, as every one knows, not uncommon in the vegetation of dry places. In the tropics it marks not only the shore plants and the vegetation of the arid plains, but also the epiphytes, which live upon the dry bark of the trees. European species are represented in this growth by the portulaccas. Among the plants is one, Bryophyllum calycinum, which has long been known to gardeners and botanists by the faculty which its leaves possess, when broken off and laid upon the ground, of developing buds on their edges, which finally become independent plants. This, instead of being a merely adventitious peculiarity, marked only under special circumstances, as has been supposed, is really the normal provision of Nature for the propagation of the plant. This species forms in the course of its growth two kinds of leaves; the entire leaves of the young plant, which are shaped like those of the common live-forever, and, at a later stage of growth, cleft leaves. The two kinds of leaves are not equally competent to form buds, but the property is a peculiarity of the cleft ones. When we gently draw the hand over a well-grown plant of Bryophyllum, we will find the feathered leaves falling like ripe fruits to the ground, while the entire leaves remain fixed upon the plant and will not be disturbed by any shaking. Examining the fallen offsets a few days afterward, we will find their upper surfaces crowned with a circle of sprouts around the edges, while to the lower side is attached a tuft of young rootlets. The plantlets live at first on the nourishing matter of the