The palm family (Arecaceae, or Palmae), with about 2,450 species, is mainly distributed in the tropics and subtropics. Palms usually have large leaves arranged at the top of an unbranched stem, and although they are tree-like, they are not strictly trees because they have no secondary growth. Palms have a long history of cultivation. They are one of the three most important economical plants. SZBG began to introduce palms at the time of the establishment of the Garden, and now cultivates 60 genera and 200 species. Many are also planted along roads, or in the vicinity of buildings, creating a rich tropical atmosphere. The following species are quite commonly planted in the Garden, Royal Palm (Roystonea regia), Alexandra's Palm (Archontophoenix alexandrae), Cane Palm (Chrysalidocarpus lutescens), Bottle Palm (Hyophorbe lagenicaulis), Triangle Palm (Neodypsis decaryi), Bismarck Palm (Bismarckia nobilis), Talipot Palm (Corypha umbraculifera), Coconut Palm (Cocos nucifera), Oil Palm (Elaeis guineensis), and Arenga Palm (Arenga pinnata).