Commelinids in the context of Turmeric

Arabinoxylan is a form of the hemicellulose xylan found in both the primary and secondary cell walls of plants which in addition to xylose contains substantial amounts of another pentose sugar, arabinose. The term arabinoxylan usually refers to feruloyl-arabinoxylan from grasses and other commelinids containing moieties of the phenolic ferulic acid that can undergo oxidative coupling (in the same way as lignin units) forming crosslinks between arabinoxylan chains and with lignin. Whilst arabinose has been found linked to xylan in non-commelinid plants, ferulic acid has not been reported on these and unlike feruloyl-arabinoxylan these arabinoxylans are not monophyletic. The remainder of this article refers to feruloyl-arabinoxylan from cell walls of grasses and other commelinid species.

The Zingiberales are flowering plants forming one of four orders in the commelinids clade of monocots, together with its sister order, Commelinales. The order includes 68 genera and 2,600 species. Zingiberales are a unique though morphologically diverse order that has been widely recognised as such over a long period of time. They are usually large herbaceous plants with rhizomatous root systems and lacking an aerial stem except when flowering. Flowers are usually large and showy, and the stamens are often modified (staminodes) to also form colourful petal-like structures that attract pollinators.

Zingiberales contain eight families that are informally considered as two groups, differing in the number of fertile stamens. A "banana group" of four families appeared first and were named on the basis of large banana-like leaves. Later, a more genetically coherent (monophyletic) "ginger group" appeared, consisting of the remaining four families. The order, which has a fossil record, is thought to have originated in the Early Cretaceous period between 80 and 120 million years ago (Mya), most likely in Australia, and diverged relatively rapidly with the families as they are known today established by the end of the period (66 Mya). Zingiberales are found throughout the tropics (pantropical) with some extension into subtropical and temperate climates. They rely on insects for pollination, together with some birds and small animals.