To this class of plants belong many of the most beautiful flowers, and all our fruit-trees, not the least important of which is the fig-tree, although the fig can hardly be called a fruit in the strict sense of the word, being a consolidated mass of flowers within a receptacle. The figs of commerce are produced from the Ficus carica, the fruit being dried in the sun; they form a considerable article of commerce. The celebrated Banyan tree (Ficus indica, fig. 24) is one of the fig tribe, it throws down branches (as do many others of this tribe) which take root in the earth and form fresh stems, so that one of the banyan trees with its off-shoots will cover a space of ground sufficient to shelter a regiment of cavalry, and many of the fig tribe, especially the sycamore (Ficus sycamorus), are planted for the sake of the shelter they supply by their broad crowns of leaves; another of the fig trees (Ficus elastica) supplies a great part of the India-rubber of commerce. [Illustration: FIG. 24--THE BANYAN TREE.] De Candolle divides the class of exogens into four sub-classes according to the arrangement of their flowers &c.; they are as follows:-- 1. THALAMIFLORÆ, the flowers of which are furnished with both calyx and corolla, the corolla having distinct petals, and the stamens hypogynous, that is, growing immediately from below the pistil. 2. CALYCIFLORÆ, having flowers with both calyx and corolla, the corolla divided into distinct petals, but the stamens always Perigynous, that is, growing upon the sides of the calyx. 3. COROLLIFLORÆ, having flowers with both corolla and calyx, the former having its petals united. 4. MONOCHLAMYDEÆ, flowers without corolla and often without a calyx. These four sub-classes have been divided into orders as follows:-- ORDERS OF THALAMIFLORÆ. 1. NYMPHACEÆ (Nymphæa alba) White Water-Lily. (Nuphar luteum) Yellow Water-Lily. This order contains water plants of great beauty, they grow in the mud at the bottom of the water, sending up long flower- and leaf-stalks so that the flowers may blossom in the air and the leaves float on the surface; the leaves are generally round and turned up slightly at the edges. The "Victoria Regia" is a magnificent specimen of this order; it originally came from Brazil, and has flowers a foot wide, leaves four or five feet across, and is sufficiently buoyant, it is said, to bear the weight of a child. The Lotus of the Nile, the blossom of which so frequently occurs on the carvings of the Egyptians as an offering to Isis, is another member of this order. [Illustration: White Water-Lily.] 2. PAPAVERACEÆ (Papaver somniferum) White Poppy. (Papaver Rhoeas) Red Poppy.