仙人掌的說法是cactus它的復(fù)數(shù)是cacti，而cereus只是仙人掌的一種，并不是仙人掌的總稱，仙人掌有很多種，比如世界上最大的仙人掌Pachycereus pringlei和世界上最小的仙人掌Blossfeldia liliputiana。一下一段是對仙人掌的簡單介紹，自己看吧。A cactus (plural: cacti, cactuses, or cactus) is any member of the succulent plant family Cactaceae, native to the Americas. They are often used as ornamental plants, but some are also crop plants.Cacti are distinctive and unusual plants, which are adapted to extremely arid and hot environments, showing a wide range of anatomical and physiological features which conserve water. Their stems have expanded into green succulent structures containing the chlorophyll necessary for life and growth, while the leaves have become the spines for which cacti are so well known.Cacti come in a wide range of shapes and sizes. The tallest is Pachycereus pringlei, with a maximum recorded height of 19.2 m,[1] and the smallest is Blossfeldia liliputiana, only about 1 cm diameter at maturity.[2] Cactus flowers are large, and like the spines and branches arise from areoles. Many cactus species are night blooming, as they are pollinated by nocturnal insects or small animals, principally moths and bats. Cacti's sizes range from small and round to pole-like and tall.