Carissa fruit grows on a bushy shrub that can grow up to 18 feet (5 1/2 metres) tall, and as wide.
An evergreen, hardy down to 26 F (- 3 C), it has dark green, glossy leaves, and double thorns up to 2 inches (5 cm) long.
The bush flowers throughout most of the summer with very fragrant, small white, waxy, five-petalled flowers. Consequently, the bears fruit year round, though mainly May through to September. The fruit is ready to pick about 2 months after the flower.
The fruit is slightly longer than it is wide, 2 1/2 inches (6 cm) long by about 1 1/2 inches (4 cm) wide. The skin ripens from green to dark red streaked with lighter red. Inside, the flesh texture is slightly granular, and very juicy. A latex comes out of them when they're cut open. There will be anywhere from 6 to 166 small brown seeds in the centre.
The taste is mildly sweet, sometimes astringent. Some think they detect a slight strawberry taste, or sweet cranberry.
Carissa are only good to eat when fully ripe. The fruit should yield to a soft squeeze. Once ripe, it bruises easily.
Carissa is often grown in the southern US as an ornamental shrub or hedge,
Cultivars include Fancy, Torrey Pines, Gifford, Extra Sweet, Alles (aka "Chesley") and Frank.
It can also be cooked with in many ways. It can be simmered down into a sauce, canned in a sugar syrup, or used for jellies and pies. Jellies made from it probably won't need additional pectin.
Don't cook it in aluminum pots.
The latex in the fruit will form a ring around the inside of any pot you cook it in. Clean off afterward with dry paper towel with some cooking oil on it.
You can also can them in a sugar syrup.
Introduced into America by Theodore L. Meade in 1886, and re-inforced there by seeds brought in by David Fairchild in 1903.