Pontederiaceae

Pontederiaceae is a family of flowering plants.

The APG IV system of 2016 (unchanged from the APG III system of 2009, the APG II system of 2003 and the APG system of 1998) places the family in the order Commelinales, in the commelinid clade, in the monocots.^[1]^[2] It is a small family of heterostylous aquatic plants, occurring in tropical and subtropical waters. Charles Darwin was interested in the specialized form of heterostyly found in the family, known as tristyly. Not all of the species are heterostylous. The family contains two genera with around 40 known species.^[3]^[4]

It is best known for the water hyacinth (Pontederia crassipes), which is an invasive species in many waterways. The highly modified Heteranthera gardneri is a submerged aquatic with a two-flowered pseudanthium.

Taxonomy

The two genera within this family are:^[4]^[5]

^ ^a ^b Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". Botanical Journal of the Linnean Society. 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. hdl:10654/18083.
^ Angiosperm Phylogeny Group (2016). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV". Botanical Journal of the Linnean Society. 181 (1): 1–20. doi:10.1111/boj.12385. ISSN 0024-4074.
^ Pellegrini, M. O. O. & Horn, C. N. (2017). "Two peculiar new species of Heteranthera Ruiz & Pavón (Pontederiaceae) from Brazil, with notes on inflorescence architecture in the family". PhytoKeys (82): 35–56. doi:10.3897/phytokeys.82.13752. PMC 5546388. PMID 28794681.
^ ^a ^b Pellegrini, M. O. O.; Horn, C. N. & Alemida, R. F. (2018). "Total evidence phylogeny of Pontederiaceae (Commelinales) sheds light on the necessity of its recircumscription and synopsis of Pontederia L." PhytoKeys (108): 25–83. doi:10.3897/phytokeys.108.27652. PMC 6160854. PMID 30275733.
^ Pellegrini, M. O. O. (2017). "Two new synonyms in Heteranthera (Pontederiaceae, Commelinales)". Nordic Journal of Botany. 35: 124–128. doi:10.1111/njb.01152.