An order of flowering plants, division Magnoliophyta (Angiospermae), in the subclass Commelinidae of the class Liliopsida (monocotyledons). The order consists of the family Juncaceae, with about 300 species, and the family Thurniaceae, with only three. Within its subclass the order is marked by its reduced, mostly wind-pollinated flowers and capsular fruits with one to many anatropous ovules per carpel. The flowers have six sepals arranged in two more or less similar whorls, both sets chaffy and usually brown or green. The ovary is tricarpellate, with axile or parietal placentation. The pollen grains are borne in tetrads, and the embryo is surrounded by endosperm. The order is most unusual among higher plants in that, together with at least some members of the Cyperaceae in the related order Cyperales, it has chromosomes with diffuse centromeres.