Commelinales

plant order
verifiedCite
While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.
Select Citation Style
Share
Share to social media
URL
https://www.britannica.com/plant/Commelinales
Feedback
Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login).
Thank you for your feedback

Our editors will review what you’ve submitted and determine whether to revise the article.

External Websites
Also known as: spiderwort order

Commelinales, the spiderwort and pickerelweed order of flowering plants, comprising more than 800 species of mostly tropical and subtropical herbs in five families: Commelinaceae, Pontederiaceae, Haemodoraceae, Philydraceae, and Hanguanaceae.

Commelinaceae, or the spiderwort family, is the largest family of the order, containing 652 species. Members are terrestrial herbs and climbers with a few epiphytes. Some are grown as garden and indoor ornamentals, such as members of Tradescantia, or the spiderwort genus (70 species), including the common spiderwort (T. virginiana) and the three wandering Jew plants (T. fluminensis, T. pallida, and T. zebrina); Commelina, or the dayflower genus (170 species), of which three are grown ornamentally (C. coelestis, C. diffusa, and C. erecta) for their blue flowers; Dichorisandra (30 species), especially D. mosaica and D. thyrsiflora, both grown as blue-flowered foliage plants; Callisia, especially C. fragrans, a fragrant waxy white-flowered hanging-basket plant; and Tradescantia spathacea, or Moses-in-the-cradle, grown as a potted plant for its purple-coloured leaves and unusual flowers.

Haemodoraceae, or the bloodwort family (116 species), includes the kangaroo paws (Anigozanthos) native to Australia, with other members of the family found in South Africa, North and South America, and Asia. The presence of phenalenones is responsible for the bright red colour of flowers and roots in some species.

trees deciduous and coniferous. trees grow on a bank of a forest in springtime in Alberta, British Columbia, Canada. logging, forestry, wood, lumber, wilderness
Britannica Quiz
All Things Green Quiz

Pontederiaceae, or the water hyacinth family, primarily contains aquatic plants that occur mainly in tropical areas around the world. The water hyacinth (Eichhornia crassipes), a native of Brazil, has become a nearly pantropical weed of still waters. Some members of this family exhibit an interesting pollination mechanism (called heterostyly) in which an individual plant possesses flowers with either long styles and short anthers or short styles and long anthers, which seem to promote cross fertilization between plants in a population.

Until recently, the closest relatives of the tropical Asian Hanguana, the only genus in Hanguanaceae, were unclear. Molecular evidence suggests that this family is closest to Commelinaceae, although some contradictory morphological evidence suggests a relationship to the ginger order, Zingiberales.

Members of Commelinales are generally small to large herbs, commonly with rhizomatous growth. The leaves, which can be linear with a sheathing base or differentiated into petiole and lamina, are either spirally arranged or distichous. The flowers are quite variable from hypogynous to epigynous, bisexual or unisexual, actinomorphic or zygomorphic, with conspicuous petals and a great variety of perianth structure and organization. The seeds possess starchy endosperm. Many members of Commelinales are rooted or free-floating aquatics that occur in marshy habitats, especially members of Pontederiaceae and Philydraceae.

Pontederiaceae, Haemodoraceae, Philydraceae, and Hanguanaceae were formerly included in the lily order, Liliales. However, the possession of similar characters with Commelinaceae—stomatal complexes with subsidiary cells, ultraviolet-fluorescent compounds in the cell walls, the Strelitzia-type of epicuticular wax, and their starchy endosperm—has resulted in reorganizing these five families together. With the gingers, grasses, and other advanced monocotyledons (that is, flowering plants characterized by a single seed leaf), they are now typically called Commelinids. For more information on the reorganization of orders under the Angiosperm Phylogeny Group II (APG II) botanical classification system, see angiosperm.

Get Unlimited Access
Try Britannica Premium for free and discover more.
W. John Kress