What is "ziziphus"

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.