Ipomoea jalapa aka High John The Conquerer

Ipomoea jalapa, or jalap, is in the bindweed family, Convolvulaceae. Kew gives its native range as Mexico to Venezuela and Ecuador. This range also takes in the Caribbean. It grows in a subtropical climate. Plants For A Future also lists it in Belize and Guatemala. That source says it grows in woods on mountain slopes. These lie in the east of Mexico. It is not native to Britain or Ireland.

Jalap climbs and keeps its leaves year-round, with tubers below ground. Plants For A Future gives its height as about 10 feet [3 metres]. Kew calls it a climbing tuberous geophyte. This means it climbs and has storage organs below ground. Its flowers have both male and female organs. The supplied evidence for this species gives no flower colour. It does not say when the plant blooms. Nor does it give details of the leaves or fruit.

Grow jalap in sun, with moist soil rich in humus. Though it likes moist soil, water must drain well. Plants For A Future lists sand, loam and clay as suited to it. The soil can be slightly acid, neutral or slightly alkaline. The same source says it can grow in light shade. It suggests a sunny edge of woods as a garden site. Its climbing form suits this site, with room to grow upward.

Frost limits outdoor use in cool climates. Plants For A Future says it has little frost tolerance. It suggests trials outside only in Britain's mildest spots with the most shelter. This is a chance to try, not a firm hardiness rating. In spring, cut back the plant or thin its shoots. To raise new plants, sow seed in a greenhouse in spring. You can also take semi-ripe cuttings in summer. The supplied sources give no pest or disease details for this species.

Plants For A Future lists no known edible uses for jalap. Its account of use as medicine concerns the tuber, not a food crop. The tuber holds resin and has a sharp, unpleasant taste. The source records taking it by mouth as a purgative for constipation. That means using it to help pass stools. It also lists use for colic and parasites in the gut. People gather roots in autumn and dry them for later use. These records of use as medicine do not prove safe home treatment. The source lists no known hazards, but this does not establish safety.