Given the question: Pick one category for the following text. The options are - company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work. Ziziphus -  Ziziphus /ˈzɪzɨfəs/ 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 2–7 cm (0.79–2.76 in) long; some species are deciduous others evergreen. The flowers are small inconspicuous yellow-green.
The answer is:
Plant