Native to Mexico. Extremely vigorous growth to 25 ft. in a single season. Bell-shaped, summer-to-fall owers are rst greenish, then violet or rose purple. The common name describes the flower form: a 2-in.-long cup of petals sits in large, saucerlike green calyx. Leaves are divided into two or three pairs of oval, 4-in. leaets; a curling tendril at the end of each leaf enables the vine to climb rough surfaces without support. 'Alba' has white blooms. 'Key Lime' has pale green flowers. Blossoms of 'Royal Plum' emerge light green, then mature to rich deep purple with a white- streaked throat and chartreuse anthers.
Blooms rst year from seed. In the Tropical South and milder parts of the Coastal South, the vine lives from year to year, eventually reaching more than 40 ft. in length and blooming heavily from spring to fall.
The hard-coated seeds may rot if sown outdoors in cool weather. Start indoors in 4-in. pots; notch seeds with a knife and press them edgewise into moistened potting mix, barely covering them. Keep moist but not wet; transplant to warm, sunny location when weather warms up. Protect from wind.