An order of flowering plants, division Magnoliophyta (Angiospermae), in the subclass Commelinidae of the class Liliopsida (monocotyledons). The names Glumiflorae, Graminales, and Poales have also been used for this order. There are only two families, the Poaceae (Gramineae), with about 8000 species, and the Cyperaceae, with nearly 4000. The Cyperales are Commelinidae with reduced, mostly wind-pollinated or self-pollinated flowers that have a unilocular, two-or three-carpellate ovary bearing a single ovule. The flowers are arranged in characteristic spikes or spikelets representing reduced inflorescences. The perianth is represented only by a set of bristles or tiny scales, or is completely missing. The leaves generally have a well-defined sheath and a narrow blade, often with a small adaxial appendage (the ligule) at the junction of the two. The stomates have two supporting cells and are arranged in straight files or rows of one or two, all oriented in the same direction. The pollen is uniformly trinucleate, and vessels are present in all vegetative organs.