help to distinguish this order include a herbaceous arborescent stem, distichous phyllotaxy, large petiolate leaves in which the petioles are often long, parallel and transverse venation diverging laterally from a prominent common midrib, and inflorescences of conspicuous colorful bracts (bracteate inflorescence) and the substitution of one to five rudimentary staminodia for fertile stamens. Leaf architecture is useful for distinguishing families within Zingiberales, based on vein pattern type, vein length per area, and other aspects of vein architecture such as angle of vein divergence, with three main types of venation recognised. These are the Zingiber-type, with square to vertically elongate areoles, the Costus-type, with horizontally elongate areoles and the Orchidantha-type with cross veins spanning multiple parallel veins. Apomorphies The apomorphies (derived characteristics common to a taxonomic group) are considered to be specialised isomorphic root hair cells, penni-parallel leaf venation, supervolute ptyxis (left and right halves of immature leaf lamina rolled into each other), diaphragmed air chambers in leaves and stem, presence of intracellular silica bodies, epigynous flowers and an inferior ovary, pollen grains without distinctive aperture but with a reduced exine layer and an elaborated intine layer, nuclear endosperm development, and arillate seeds. Taxonomy "The Zingiberiflorae, whether treated as a separate superorder, as here, or an order in a more widely circumscribed unit, is one of the most indisputably natural suprafamilial groups." History The Zingiberales have always been considered a unique and coherent (monophyletic) group, although accounting for <4% of extant monocots, which has led some authors to suggest they should constitute a higher taxonomic rank than order. For a brief history of the taxonomy of this order, see Scitamineae, and Kress 1990. They were first described by August Grisebach, their botanical authority, in 1854 as Zingiberides, an order of monocotyledons, subdivided into two families, Scitamineae and Musaceae. Based on morphological grounds alone, early systems, such as Bentham and Hooker (1883) placed the Scitamineae as an Ordo (family) of the Epigynae alliance in the monocotyledons, incorporating both of Grisebach's families. Later systems such as the Engler system (1903) and the Wettstein system (1924), also considered Scitamineae as a monocotyledon order and were influential for a long period of time. Variants included Scitaminales (Warming 1912). Hutchinson (1926), although initially using Scitamineae, later followed Takenoshin Nakai (1930). in adopting Zingiberales as the name for the order (6 families) in Division Calyciferae, although credit is generally given to Nakai. This usage was followed by