Monocotyledons (/ˈmɒnɵˈkɒtɪˈliːdən/), also known as monocots, are plants whose seeds typically contain only one embryonic leaf, or cotyledon. They constitute one of the major groups into which flowering plants (or angiosperms) have traditionally been divided, the rest of the flowering plants having two cotyledons and being classed as dicotyledons, or dicots. However, molecular phylogenetic research has shown that the monocots form a monophyletic group – a clade – since they comprise all the descendants of a common ancestor, but that dicots do not form a monophyletic group. Monocots have almost always been recognized as a group, but with various taxonomic ranks and under several different names. The APG III system of 2009 recognises a clade called ""monocots"" but does not assign it to a taxonomic rank.According to the IUCN there are 59,300 species of monocots. The largest family in this group (and in the flowering plants as a whole) by number of species are the orchids (family Orchidaceae), with more than 20,000 species. About half as many species belong to the true grasses, Poaceae, who are economically the most important family of monocots: in agriculture the majority of the biomass produced comes from monocots. These include not only major grains (rice, wheat, maize, etc.), but also forage grasses, sugar cane, and the bamboos. Other economically important monocot cultures include various palms (Arecaceae), bananas (Musaceae), gingers and their relatives, turmeric and cardamom (Zingiberaceae) and onions (Amaryllidaceae), which includes such ubiquitously used vegetables as onions and garlic. Additionally, plants cultivated for their blooms are also from the monocot group, notably lilies, daffodils, irises, amaryllis, cannas, bluebells and tulips.