Citrullus colocynthis aka Bitter Apple

Citrullus colocynthis is a vine in the gourd family. It lives for more than one year. People call it bitter apple, bitter cucumber, and colocynth. Its native range runs from Macaronesia and the Mediterranean to Myanmar. It also covers northeast tropical Africa and northern Kenya. It grows in dry parts of the tropics and subtropics. Wild plants grow on dunes and grasslands, and in open woods. They also grow by rivers and roads, and on disturbed ground.

Long stems grow from a woody, thick, tuber-like rootstock. They trail or climb, and grow fast. They spread several feet across the ground. PFAF gives their length as about 10 feet [3 metres]. The stems look like those of a watermelon vine. The small, hard fruits hold bitter pulp. They measure about 0.16–0.26 feet [0.05–0.08 metres] across. Cut them open to find white flesh and seeds.

Grow this vine in full sun and light soil that drains well. It grows in sand or loam, even with few soil nutrients. Soil can be acid, neutral, or slightly alkaline. Once plants take root, they cope well with drought. Dry, sunny weather helps crops yield more. Damp air and wet weather reduce yields. Yet plants grown as crops can stand high rainfall when conditions suit them. They grow best at daytime temperatures of 23–32°C. PFAF lists USDA zones 10–12. This plant is frost-sensitive. Frost at 0°C can cause great harm to young growth. Temperatures of −5°C or below can kill mature growth.

People gather wild plants for food, medicine, and seed oil. Some regions also grow the vine for use in medicine. The dried pulp of unripe fruit acts as a very strong laxative. Records also list uses to treat skin problems and rheumatism. These uses do not make it safe for home remedies. The seeds yield a pale yellow oil. Growers can raise new plants from seed. PFAF also warns that this species may become a weed.

Reports list cooked fruit as food, along with roasted or ground seeds. Fruit preparation includes boiling it more than once to make it less bitter. Treat these records with care. Some seed uses may refer to watermelons named in error. The plant holds compounds that can cause serious poisoning. Too much can cause gut pain, vomiting, and diarrhoea. It can also harm the heart, liver, and kidneys. Past use as food and medicine does not remove these risks.