Citrullus lanatus is a prostrate or climbing annual with several herbaceous, rather firm and stout stems up to 3 m long; the young parts are densely woolly with yellowish to brownish hairs while the older parts become hairless. The leaves are herbaceous but rigid, becoming rough on both sides. The leaf stalks are somewhat hairy and up to 150 mm long. The tendrils are rather robust and usually divided in the upper part. Male and female flowers occur on the same plant (monoecious) with the flower stalk up to 40 mm long and hairy. In southern Africa the flowering time of C. lanatus is mostly from January to April and the fruiting time mostly from February to May. Dry or rainy years will influence flowering and fruiting. The rind in the ripe fruit is hairless and smooth, hard but not woody. In the wild forms the rind is pale or grey-green, usually mottled with irregular longitudinal bands of dark green or grey-green. In cultivated forms the rind is often concolorous yellowish to pale or dark green, or mottled with darker green, or marbled with a darker shade. The flesh in the wild form and some cultivated forms (citron watermelon) is firm and rather hard, white, green-white or yellowish. In cultivated forms the flesh is somewhat spongy in texture but very juicy and soft, pink to bright red-pink. Citrullus lanatus can be recognized by its large fruit which is unique in the Cucurbitaceae of southern Africa and also by the dense yellowish to brownish hairs on the younger plant parts.

The fruit of Citrullus lanatus subsp. lanatus var. citroides, known as the citron melon or in Southern Africa as the Makataan, is larger than the tsamma, also sweet and has a more or less concolorous rind and yellowish flesh. The fruits are mostly used as fodder, but also for the production of citron peel or pectin. In southern Africa it has been cultivated since pre-colonial times with other crops such as sorghum and maize. The tender young leaves and fruits are cooked as green vegetables, while the fruit flesh may be cooked as porridge with maize meal. It is also a valuable stock feed, especially in times of drought. The makataan is an old favourite for making jam or preserve. The flesh from just below the rind is cut into squares and used to make what is called makataankonfyt. The fruit of the makataan can also be pickled.