Monocotyledons or monocots are a group of flowering plants. They are usually ranked as a class, originally called the Monocotyledoneae but now named Liliopsida after the type genus, Lilium. The remaining flowering plants comprise the dicotyledons or dicots. They are distinguished by the number of cotyledons, or embryonic leaves, within their seeds: dicots have two, and monocots have one.
The monocots are considered to form a monophyletic group which evolved from an early dicot. The earliest fossils presumed monocot remains date from the early Cretaceous period. The largest modern monocot family are the Orchidaceae (orchids), which have specialized in insect pollination, many species producing the most complex of all flower structures. The second largest and perhaps most notable family, the Poaceae (true grasses), have evolved in the opposite direction, becoming highly specialized for wind pollination.
The APG II Classification System, created by the Angiosperm Phylogeny Group, identifies ten orders of monocots and two families not yet assigned to an order, which are divided into base Monocots and Commelinids:
- Base Monocots