Hibiscus calyphyllus aka Large Yellow Wild Hibiscus

Hibiscus calyphyllus is a perennial: it lives for several years. It belongs to the mallow family, Malvaceae. It can form a shrub as its stems turn woody. Its native range runs from Eritrea south to South Africa. It includes the western Indian Ocean and Arabian Peninsula too. Kew places it in the tropics, where some seasons are dry. The RHS gives Rock's hibiscus as a common name. It also lists the names Hibiscus rockii and Hibiscus calycinus.

Useful Tropical Plants gives its height as about 6.6 feet [2 metres]. Its fuller account gives a top height of 9.8 feet [3 metres]. The stems can last and grow woody to varying degrees. Wild plants grow in thickets and along forest roads. They grow by rivers and at the edges of forests too. They also grow on ground that has been disturbed. Records reach heights above sea level of about 6,890 feet [2,100 metres]. People gather wild plants for food, medicine, and stem fibre. They also grow this species for its looks.

The account of how to grow it reports success in a range of soils. In Tanzania, it grows where yearly rain totals 1,100–1,600 millimetres. This tells us where it grows, not how to water it. The species accounts give no firm limits for light or frost. Grow plants from seed or half-ripe stem cuttings. Sow seeds straight in the ground or in pots. The account says seeds tend to sprout soon after sowing. Move young plants grown in pots to their own pots once large enough to handle. Plant them out at about 0.3 feet [0.1 metres] tall or more.

People cook the leaves as a vegetable, not eat them raw. They first wilt and chop them. Then they boil them with other greens. The leaves help thicken the sauce and change its texture. People eat modest amounts of this dish, often with rice. Useful Tropical Plants reports no known hazards for this species. This does not prove it is safe for pets or all uses.

In folk medicine, people put crushed leaves on sores and wounds. They also boil roots for steam baths and drinks. The source lists these as folk treatments for pneumonia. It gives no proof that they work. The stems also yield fibre. The supplied accounts give no pest or disease details for this species.