About Carissa ovata R.Br.
This entry addresses Carissa ovata R.Br., and the original description covers Carissa spinarum, commonly known as conkerberry or bush plum. Carissa spinarum is a large shrub in the dogbane family, Apocynaceae. It is widely distributed across tropical Africa, Southern Asia, Australia, and various islands of the Indian Ocean, and is most well-known in Australia, where it is also called currant bush, and more ambiguously native currant or black currant. It is not closely related to plums of the genus Prunus or true currants of the genus Ribes, which belong to entirely different eudicot lineages. In India, it is called wild karanda or wild karavanda, in reference to the related karanda, Carissa carandas. Carissa spinarum is often discussed under its many obsolete synonyms. It grows as a multi-stemmed shrub reaching 0.5 to 3 meters (1.6 to 9.8 feet) in height. Its leaves are glossy green, arranged oppositely, and shaped from narrow ovate to lanceolate, measuring 1 to 5 centimeters (0.4 to 2.0 inches) long. Its branches bear thorns that are 1 to 3 centimeters (0.4 to 1.2 inches) long. White, star-shaped flowers around 1 centimeter (0.4 inches) across are followed by ovate green berries 1 to 2 centimeters (0.4 to 0.8 inches) long, which turn black or dark purple when ripe. Carissa spinarum is most often found in semiarid coastal regions on fine-textured soils such as clays and clay-loams. In more arid regions, the plant tends to grow only in areas of higher moisture, such as at the base of hills or floodout areas. It has a high ecological tolerance and can live in a wide range of habitats. In Australia, for example, it is frequently found growing alongside Eucalyptus brownii, poplar box (Eucalyptus populnea), gidgee (Acacia cambagei), or brigalow (Acacia harpophylla). It grows in coastal rainforest, gallery forest, and vine thickets in regions that get more than 900 millimeters (35 inches) of annual rainfall, as well as in softwood scrubs and open eucalypt savannas that get less than 700 millimeters (28 inches) of annual rainfall. Conkerberries are edible only when fully ripe, and have a sweet flavour. As is typical for members of Apocynaceae, the milky sap of this plant and its unripe fruit are poisonous. The ripe fruit is a popular traditional bush tucker food for Australian Aborigines living in Central Australia. In the Arrernte language the fruit is called merne arrankweye, anwekety in Anmatyerr, and nganango in Pintupi. The fruits are also a popular food source for the Australian bustard, emu, and many other birds across the plant's range. Its leaves provide food for butterflies such as the Australian crow (Euploea core) and moths such as some hawkmoths. Carissa spinarum is frequently a weed in grazing land in northern Australia. It chokes out grasses, reduces the ability of livestock to feed, interferes with stock handling, and provides a refuge for vermin. The plant can reproduce rapidly by layering, is difficult to control via mechanical methods, and is expensive to manage with herbicides. On the other hand, it has been used in attempts to restore small-bird habitat in disturbed dry rainforest in Queensland, Australia. The Maasai people of Kenya use parts of the plant medicinally to treat joint and muscle pain. Fruit extracts from the plant have shown antioxidant and antidiabetic properties.
