The other plants likely to be met with by the student belong either to the _Verbenaceæ_, represented by the showy verbenas of the gardens, and our much less showy wild vervains, also belonging to the genus _Verbena_ (Fig. 121, _E_); or to the plantain family (_Plantagineæ_), of which the various species of plantain (_Plantago_) are familiar to every one (Fig. 121, _G_, _I_). The latter seem to be forms in which the flowers have become inconspicuous, and are wind fertilized, while probably all of its showy-flowered relatives are dependent on insects for fertilization. The third order (_Contortæ_) of the _Anisocarpæ_ includes five families, all represented by familiar forms. The first, the olive family (_Oleaceæ_), besides the olive, contains the lilac and jasmine among cultivated plants, and the various species of ash (_Fraxinus_), and the pretty fringe-tree (_Chionanthus_) (Fig. 122, _A_), often cultivated for its abundant white flowers. The other families are the _Gentianaceæ_ including the true gentians (_Gentiana_) (Fig. 122, _F_), the buck-bean (_Menyanthes_), the centauries (_Erythræa_ and _Sabbatia_), and several other less familiar genera; _Loganiaceæ_, with the pink-root (_Spigelia_) (Fig. 122, _D_), as the best-known example; _Apocynaceæ_ including the dog-bane (_Apocynum_) (Fig. 122, _H_), and in the gardens the oleander and periwinkle (_Vinca_). [Illustration: FIG. 122.--_Anisocarpous sympetalæ_ (_Contortæ_). _A_, flower of fringe-tree, _Chionanthus_ (_Oleaceæ_), × 1. _B_, base of the flower, with part of the calyx and corolla removed, × 2. _C_, fruit of white ash, _Fraxinus_ (_Oleaceæ_), × 1. _D_, flower of pink-root, _Spigelia_ (_Loganiaceæ_), × ½. _E_, cross-section of the ovary, × 3. _F_, flower of fringed gentian, _Gentiana_ (_Gentianaceæ_), × ½. _G_, diagram of the flower. _H_, flowering branch of dog-bane, _Apocynum_ (_Apocynaceæ_), × ½. _I_, vertical section of a flower, × 2. _J_, bud. _K_, flower of milk-weed, _Asclepias_ (_Asclepiadaceæ_), × 1. _L_, vertical section through the upper part of the flower, × 2. _gy._ pistil. _p_, pollen masses. _an._ stamen. _M_, a pair of pollen masses, × 6. _N_, a nearly ripe seed, × 1.] The last family is the milk-weeds (_Asclepiadaceæ_), which have extremely complicated flowers. Our numerous milk-weeds (Fig. 122, _K_) are familiar representatives, and exhibit perfectly the peculiarities of the family. Like the dog-banes, the plants contain a milky juice which is often poisonous. Besides the true milk-weeds (_Asclepias_), there are several other genera within the United States, but mostly southern in their distribution. Many of them are twining plants and occasionally cultivated for their showy flowers. Of the cultivated forms, the wax-plant (_Hoya_), and _Physianthus_ are the commonest.