shaded over-arching walks or avenues. The smooth polished and often lightly-waving and bending stems of these tropical grasses are taller than our alders and oaks. The form of Gramineæ begins even in Italy, in the Arundo donax, to rise from the ground, and to determine by height as well as mass the natural character and aspect of the country.
The form of Ferns,[28] as well as that of Grasses, becomes ennobled in the hotter parts of the globe. Arborescent ferns, when they reach a height of above 40 feet, have something of a palm-like appearance; but their stems are less slender, shorter, and more rough and scaly than those of palms. Their foliage is more delicate, of a thinner and more translucent texture, and the minutely indented margins of the fronds are finely and sharply cut. Tree ferns belong almost entirely to the tropical zone, but in that zone they seek by preference the more tempered heat of a moderate elevation above the level of the sea, and mountains two or three thousand feet high may be regarded as their principal seat. In South America the arborescent ferns are usually found associated will the tree which has conferred such benefits on mankind by its fever-healing bark. Both indicate by their presence the happy region where reigns a soft perpetual spring. '
I will next name the form of Liliaceeous plants,[29] (Amaryllis, Ixia, Gladiolus, Pancratium) with their flag-like leaves and superb blossoms, of which Southern Africa is the principal country; also the Willow form[30], which is indigenous in all parts of the globe, and is represented in the elevated plains of Quito, (not in the shape of the leaves but
