Zizyphus spina-christi (L.) Willd.

Ziziphus spina-christi is a shrub, sometimes a tall tree, reaching a height of 20 m and a diameter of 60 cm; bark light-grey, very cracked, scaly; trunk twisted; very branched, crown thick; shoots whitish, flexible, drooping; thorns in pairs, one straight, the other curved. Leaves glabrous on upper surface, finely pubescent below, ovate-lanceolate or ellipsoid, apex acute or obtuse, margins almost entire, lateral veins conspicuous. Flowers in cymes, subsessile, peduncle 1-3 mm. Fruit about 1 cm in diameter. There are 2 varieties: var. spina-christi is a tree with white branches, leaves larger, ovate-lanceolate with an acute or obtuse apex, 2.5-8.5 cm long and 1-3.5 cm wide, margins slightly crenate, 3 strong veins from the base, lateral veins inconspicuous; flowers many per cyme, peduncle up to 1.5 cm; fruit 2 cm in diameter; var. microphylla Hochst ex A. Rich. is a very bushy shrub, leaves are widely ellipsoid or ovate-ellipsoid, rounded at the tip, 1-3 cm long and just as wide, margins almost entire, basal veins not reaching the apex, 1-2 strong lateral veins on each side of the central vein; branches brown-reddish; fruits up to 1 cm in diameter. The name ‘Ziziphus’ is often erroneously written as Zizyphus. The generic name is derived from the latinized version of the Arabic vernacular name ‘zizouf’ for Z. jujuba. The specific name is derived from its common name Christ thorn.

Z. spina-christi prefers alluvial plains with deep soils but it can also grow on clay where water is available and saline soils.

Z. spina-christi is native to a vast area of Africa stretching from Mauritania through the Sahara and Sahelian zones of west Africa to the Red Sea. It is drought hardy, very resistant to heat and can be found in desert areas with even 100 mm rainfall annually. It prefers edges of ponds, river and wadi banks where groundwater is available. The tree is frost tender, can withstand water logging for up to 2 months and 8-10 months of dry season. It is an aggressive colonizer, forming spiny, impenetrable thickets.

Some attempts have been made to plant Christ thorn as part of range improvement programs e.g. in Djibouti. In various countries, including Abu Dhabi, the species has been planted for windbreaks, sand dune fixation and reforestation of drylands. Agroforestry systems combing Christ thorn and various cereals also exist in the Sudan.

Propagation is by bare-rooted seedlings and cuttings. 60-80 % germination is realized, seedlings growth rate is medium reaching plantable size in 4-5 months in the nursery.

The tree develops an extremely deep taproot and has extraordinary regenerative power. It is an aggressive colonizer, coppices well and is long lived, forming spiny, impenetrable thickets.

There are 15 000 seeds/kg. Seed storage behaviour is orthodox. Viability is maintained in hermitic air-dry storage and cool temperatures. The hard, woody shells of the seeds should be cracked with a hammer and the shelled seeds soaked overnight in lukewarm water or scarified in concentrated sulphuric acid for 2 hours then cold stratified before planting.

Erosion control: Because it develops a very deep taproot and spreading lateral roots, it is used for stabilizing sand dunes and other unstable soils. Shade or shelter: Christ thorn is planted around towns and villages for shade. It makes useful windbreaks and shelterbelts. Soil improver: The tree improves soil quality by increasing available Phosphorus. Boundary or barrier or support: The thorny branches are used for fencing. It can also be grown to form a stock-proof living fence. Intercropping: Z. spina-christi is intercropped with millet in West Africa.

Food: The fruit is edible and occasionally sweet, but the flavour and texture are inferior to other Ziziphus spp. which have been domesticated in Africa and especially in northern India. Average size is about 50 g, with a single large seed. The fruits contain 14.16% sugar and about 1.6% vitamin C. Fodder: The leaves provide valuable animal forage and fodder under open grazing conditions, but the nutritional value is apparently not high for most domestic livestock. The fruits are eaten by sheep and goats and the foliage by camels. Fuel: Its wood yields an excellent charcoal, but given the current status of the species, and its slow growth rate, this usage is certainly to be discouraged. Timber: The termite resistant red or dark brown wood is hard and heavy, used for spear shafts, posts, roofing beams, utensils and cabinet making. Alcohol: An alcoholic drink is made from the fruits. Medicine: The leaves contain various alcaloids, including ziziphine, jubanine and amphibine, alpha terpinol, linalol and diverse saponins. In the Sahel region, the roots are used to treat headaches, while the spines or ashes of this species are applied to snake bites. Boiled leaves are applied to various surface wounds, and also have antihelminthic and anti-diarrhetic properties. In Egypt and the southern Sahara, a narcotic beverage is made from the fruits and which is considered to be a tranquilliser and sedative. In Morocco, the fruits are used as an emollient and astringent agent. It also is reputed to reduce abscesses and boils while a cataplasm of young leaves is also used to reduce eye inflammations. Poison: It has been reported that applying Christ thorn bark in larger doses reduces nematode activity in cereal fields and leads to significant increase in the yield of sunflowers (Ismail, 1998).