Similar in their habits, but differing much in appearance from the sundews, are the pitcher-plants (_Sarraceniaceæ_), of which one species (_Sarracenia purpurea_) is very common in peat bogs throughout the northern United States. In this species (Fig. 105, _A_, _B_), the leaves form a rosette, from the centre of which arises in early summer a tall stalk bearing a single, large, nodding, dark-reddish flower with a curious umbrella-shaped pistil. The leaf stalk is hollow and swollen, with a broad wing on one side, and the blade of the leaf forms a sort of hood at the top. The interior of the pitcher is covered above with stiff, downward-pointing hairs, while below it is very smooth. Insects readily enter the pitcher, but on attempting to get out, the smooth, slippery wall at the bottom, and the stiff, downward-directed hairs above, prevent their escape, and they fall into the fluid which fills the bottom of the cup and are drowned, the leaf absorbing the nitrogenous compounds given off during the process of decomposition. There are other species common in the southern states, and a California pitcher-plant (_Darlingtonia_) has a colored appendage at the mouth of the pitcher which serves to lure insects into the trap. Another family of pitcher-plants (_Nepentheæ_) is found in the warmer parts of the old world, and some of them are occasionally cultivated in greenhouses. In these the pitchers are borne at the tips of the leaves attached to a long tendril. Two other families of the order contain familiar native plants, the rock-rose family (_Cistaceæ_), and the St. John's-worts (_Hypericaceæ_). The latter particularly are common plants, with numerous showy yellow flowers, the petals usually marked with black specks, and the leaves having clear dots scattered through them. The stamens are numerous, and often in several distinct groups (Fig. 105, _C_, _D_). The last order of the _Aphanocyclæ_ (the _Columniferæ_) has three families, of which two, the mallows (_Malvaceæ_), and the lindens (_Tiliaceæ_), include well-known species. Of the former, the various species of mallows (Fig. 106, _A_) belonging to the genus _Malva_ are common, as well as some species of _Hibiscus_, including the showy swamp _Hibiscus_ or rose-mallow (_H. moscheutos_), common in salt marshes and in the fresh-water marshes of the great lake region. The hollyhock and shrubby _Althæa_ are familiar cultivated plants of this order, and the cotton-plant (_Gossypium_) also belongs here. In all of these the stamens are much branched, and united into a tube enclosing the style. Most of them are characterized also by the development of great quantities of a mucilaginous matter within their tissues. The common basswood (_Tilia_) is the commonest representative of the family _Tiliaceæ_ (Fig. 106, _G_). The nearly related European linden, or lime-tree, is sometimes planted. Its leaves are ordinarily somewhat smaller than our native species, which it, however, closely resembles.