Triphasia trifolia aka Lime Berry

Triphasia trifolia is an evergreen shrub in the citrus family, Rutaceae. Its common names include limeberry and myrtle lime. Kew gives its native range as Bangladesh to Papuasia. Useful Tropical Plants notes that long cultivation has blurred its origins. People grow it across tropical and subtropical regions. It serves as an ornamental, hedge plant, and fruit crop.

Growth is slow, with plants reaching 3–10 feet [1–3 metres]. Some reach 23 feet [7 metres], though this is unusual. It can take the form of a small tree. Sharp spines arm the plant, and suckers can form thickets. The leaves stay green throughout the year. Clear dots mark their surface, and bruised leaves release a resinous scent. The stems also yield a gum, though its uses remain unclear.

White flowers smell like orange blossom. Each flower has both male and female organs. The red, fleshy fruit measures about 0.6 inches [15 millimetres] across. It has a lemon scent and tastes sweet when fully ripe. The flesh is juicy, aromatic, and somewhat mucilaginous. People eat the fruit raw or cook it. They also pickle it or use it in jam. Plants For A Future gives its food value two out of five.

Give limeberry a sunny site and soil that drains well. Useful Tropical Plants also reports success in partial shade. Plants For A Future favours loam enriched with compost and sand. It lists a preferred soil pH of 5–6. The plant accepts dry or moist soil but dislikes waterlogging. Winter wet is a problem. It can survive brief, light frost, but needs protection from harder freezes. Most British reports call for greenhouse shelter. One report records an outdoor plant fruiting in Cornwall. Plants For A Future lists USDA zones 9–12.

Its scent and evergreen form give it value in warm gardens. Leaves have uses in scented baths and cosmetics. Traditional treatments use them for diarrhoea, colic, and skin complaints. These reported uses do not establish medical safety or benefit. Both plant-use sources list no known hazards. The sharp spines still warrant care when handling it. Its spread also needs thought before planting. It has escaped gardens on many Pacific islands. There, dense stands can make the understorey hard to pass through.