When someone says Endive, they generally mean this kind with small, curly leaves.
All its leaves are crunchy and slightly bitter. The outside leaves are green; the inside leaves are pale green or creamy-white. The outside leaves are stronger-tasting than the inside ones.
Varieties include Lora, Salad King (a standard now in South-western American farm production), Frisée (lacy leaves), and Ruffec (tolerates cold, so may be planted in early spring or grown into late fall.)
For the broader-leafed version of Endive, see the separate entry on Escarole.