Dracaena (/drəˈsiːnə/) is a genus of about 120 species of trees and succulent shrubs. The formerly accepted genera Pleomele and Sansevieria are now included in Dracaena. In the APG IV classification system, it is placed in the family Asparagaceae, subfamily Nolinoideae (formerly the family Ruscaceae). It has also formerly been separated (sometimes with Cordyline) into the family Dracaenaceae or placed in the Agavaceae (now Agavoideae). Species of Dracaena have a secondary thickening meristem in their trunk, termed Dracaenoid thickening by some authors,[citation needed] which is quite different from the thickening meristem found in dicotyledonous plants. This characteristic is shared with members of the Agavoideae and Xanthorrhoeoideae among other members of the Asparagales. (Source: Wikipedia.org, CC BY-SA)