Ziziphus is a genus of about 40 species of spiny shrubs and small trees in the buckthorn family, Rhamnaceae, distributed in the warm-temperate and subtropical regions throughout the world. The leaves are alternate, entire, with three prominent basal veins, and long; some species are deciduous, others evergreen. The flowers are small, inconspicuous yellow-green. The fruit is an edible drupe, yellow-brown, red, or black, globose or oblong, long, often very sweet and sugary, reminiscent of a date in texture and flavour.
Overview
The generic name is derived from zizfum or zizafun, the Persian word for Z. lotus. They are Rhamnaceae, near to the buckthorn genus.
Ecology
Ziziphus species are used as food plants by the larvae of some Lepidoptera species including Bucculatrix zizyphella, which feeds exclusively on the genus, and Endoclita malabaricus. Well known species includes Ziziphus jujuba, Ziziphus spina-christi from southwestern Asia, Ziziphus lotus from the Mediterranean region, and ber, which is found from western Africa to India. Ziziphus joazeiro grows in the Caatinga of Brazil. Ziziphus celata is listed as an endangered species in the United States. The fruits are an important source for birds, which eat the whole fruit and regurgitate the seeds intact, expanding the seeds in the best conditions for germination. Secondly, seed dispersal is carried out by mammals or fishes. The fruit is energy-rich because of the large amount of sugar it contains. It is cultivated and eaten fresh, dry, and in jam. It is also added as a base in meals and in the manufacture of candy. The leaves can be either deciduous or evergreen depending on species, and are aromatic. They are temperate or tropical plants, having a great range. They are most abundant where annual average temperatures are between and and minimum winter temperatures are not lower than. They prefer locations with a high temperature coupled with humidity. They require a deep soil, fresh, soft, siliceous-calcareous nature or limestone-clay-silica-clay and subsurface permeable, with pH between 5.5 and 7.8. In excessively sandy or clay soils which may be affected by standing water, the plants do not grow well. Many species are very sensitive to drought, and if the land is excessively dry and of calcareous nature, they may resent the lack of moisture. At the slightest drought, premature fruit drop is frequent. Ziziphus has several relict species living in temperate areas. These species can not endure the harsh winters of temperate continental climates. The ecological requirements of the genus are mostly those of vigorous species with a great ability to propagate in conducive habitats. This genus is adapted mostly to high rainfall and humidity, but some species are deciduous, living in Mediterranean humid climate. The deciduous Ziziphus species lose all of their leaves for part of the year depending on variations in rainfall. In deciduous species in tropical, subtropical, and arid regions, leaf loss coincides with the dry season. They grow mostly in tropical forests but have also been found in stubbles, pastures, coastal ranges, tropical mountain areas, and wet to dry interior regions. The family is distributed throughout tropical and subtropical areas and in cloud forest. The differences are ecological adaptations to different environments over a relatively dry-wet climate. Species in less humid environment are smaller or less robust, with less abundant and thinner foliage and have oleifera cells that produce trees with a more fragrant aroma.
