P. Wrayi (Wray's).—Flowers 5 in. long by 8 in. in diameter; sepals brown on the outside, yellow inside; petals yellowish-white, fragrant when first expanded.
CHAPTER VII.
THE GENUS CEREUS.
(From cereus, pliant; in reference to the stems of some species.)
VER 200 distinct species of Cereus are, according to botanists, distributed over the tropical and temperate regions of America and the West Indies, extending to the Galapagos, or "Tortoise" Islands, 200 miles off the coast of Peru. It was in these islands that the late Charles Darwin found several small kinds of Cereus, some of them growing near the snow-line in exposed situations on the highest mountains. In Mexico, C. giganteus, the most colossal of all Cacti, is found rearing its tall, straight, columnar stems to a height of 60 ft., and branching near the top, "like petrified giants stretching out their arms in speechless pain, whilst others stand like lonely sentinels keeping their dreary watch on the edge of precipices." In the West Indies most of the night-flowering kinds are common, their long, creeping stems clinging by means of aerial roots to rocks, or to the exposed trunks of trees, where their enormous, often fragrant, flowers are produced in great abundance, expanding only after the sun has set. Between these three distinct groups we find among the plants of this elegant genus great variety both in size and form of the stem and in the flower characters of the different species. A large proportion of the 200 kinds known are not cultivated in European gardens, and perhaps for many of them it is not possible for us to provide in our houses the peculiar conditions they require for their healthy existence. But there are a good many species of Cereus represented in gardens, even in this country, and among them we shall have no difficulty in finding many useful and beautiful kinds, such as may be cultivated with success in an ordinary greenhouse or stove. Lemaire, a French writer on Cactuses, groups a number of species under the generic name of Echinocereus; but as this name is not adopted in England, it is omitted here, all the kinds being included under Cereus.