!Nara is a leafless, thorny, melon-bearing bush that is endemic to the Namib Desert. The plants occur sporadically throughout this coastal desert from Port Nolloth in South Africa (last recorded in 1925) to Namibe in Southern Angola, with the greatest concentrations around the Kuiseb River Delta, and the most eastern distribution from around Sossusvlei. Recent explorative fieldwork has improved understanding of a more widespread occurrence in westward flowing ephemeral rivers of the northern Namib.
Plants are restricted to sand desert, often at the base of dunes, and are mostly associated with rivers ending in or flowing through the Namib, and their palaeochannels. They are absent from stony desert plains.
The plants form hummocks, which may extend over large surface areas, 1500 m2 or more, ever-increasing as the sand continues to accumulate around the plant. The spiny domes of stems may project a centimeter to one meter or higher above the hummocks. !Nara, where it occurs, is usually the dominant feature in the landscape and is not associated with other vegetation, since few other plants can survive the wind-borne sand and rainless climate. The tangled, grey- to yellow-green masses of stems enable it to be easily recognised from a distance. As the plants are leafless, a desert adaptation taken to the extreme, it is these ridged stems and paired spines of 20–30 mm long, making up almost 50% of the total surface area of the plant, which enable the plant to photosynthesise. A thick, robust tap-root system, which may extend more than 50 m below the surface, efficiently draws moisture from deep underground. This, coupled with structural adaptations to limit evaporative water losses from the surface of the plant, enables the !nara to survive for many years without rain.
The plants are dioecious (male and female flowers on separate plants), with male flowers appearing throughout the year, and female flowers mostly during spring. Sex expression in cucurbits is controlled by environmental as well as genetic factors, and may explain discrepancies in the life-cycle events, such as flowering of northern populations, revealed during recent fieldwork.
!Nara fruit are round and melon-like, weighing mostly around 1 kg but sometimes reaching up to 2.5 kg. They are pale-green even when ripe, and spiny on the outside. The fruit has a mass of watery, orange-yellow pulp, which is sweet and aromatic, tasting like avocado or a cross between cucumber and pineapple. Toxic and potentially therapeutic compounds called cucurbitacins, which cause bitterness in the fruit, are currently under investigation in !nara. Further study of these compounds could elucidate taxonomic relationships; provide evidence to support the hypothesis of pre-selection as a husbandry practice; as well as present opportunities for novel pharmaceutical product development due to their professed anticancer properties. The large seeds are white to cream in colour with buttery kernels.