The members of family Cactaceae are a group of dicotyledonous flowering plants that are primarily native to various dry or seasonally dry habitats in North and South America. Due to the presence of specialized fleshy stems, they are classified as stem succulents. Leaves are not produced in most species, although there are some leafy species in a few genera. There are more than sixteen hundred species of cacti, which are contained in approximately one hundred genera. All cacti share the unique morphological features of having most, if not all, of their secondary stems condensed into structures called areoles. These are the places on the stems from which the spines develop. Spines are modified leaves that have become hardened and sharp, thereby providing protection for the plants from herbivores in addition to providing some shade to the stems.
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