The most characteristic members of the order are twining plants with generally smooth heart-shaped leaves and large showy white or purple flowers, as, for instance, the greater bindweed of English hedges, Calystegia sepium, and many species of the genus Ipomaea, the largest of the order, including the "convolvulus major" of gardens, and morning glory.
The creeping or trailing type is a common one, as in the English bindweed (Convolvulus arvensis), which has also a tendency to climb, and Calystegia Soldanella, the sea-bindweed, the long creeping stem of which forms a sandbinder on English seashores; a widespread and efficient tropical sand-binder is Ipomaea Pes-Caprae.
Flowered species of Ipomaea with narrow tubes are adapted for the visits of honey-seeking birds.
The largest genus, Ipomaea, has about 400 species distributed throughout the warmer parts of the earth.
The tubers of Ipomaea Batatas are rich in starch and sugar, and, as the "sweet potato," form one of the most widely distributed foods in the warmer parts of the earth.
Species of Ipomaea (morning glory), Convolvulus and Calystegia are cultivated as ornamental plants.
JALAP, a cathartic drug consisting of the tuberous roots of Ipomaea Purga, a convolvulaceous plant growing on the eastern declivities of the Mexican Andes at an elevation of 5000 to 8000 ft.
, Jalap (Ipomaea Purga); about half natural size.
A third variety of jalap known as woody jalap, male jalap, or Orizaba root, or by the Mexicans as Purgo macho, is derived from Ipomaea orizabensis, a plant of Orizaba.
The natural and forest products of Mexico include the agave and yucca (ixtle) fibres already mentioned; the " ceibon " fibre derived from the silk-cotton tree (Bombax pentandria); rubber and vanilla in addition to the cultivated products; palm oil; castor beans; ginger; chicle, the gum extracted from the " chico-zapote " tree (Achras sapota); logwood and other dye-woods; mahogany, rosewood, ebony, cedar and other valuable woods; " cascalote " or divi-divi; jalap root (Ipomaea); sarsaparilla (Smilax); nuts and fruits.