The fossil record consists especially of seeds, but also pollen, stems, leaves, and flowers. It extends back to the Cretaceous.[7][8] The crown group of the Nymphaeales has been estimated to be about 112 million years old.[9] Some have suggested that this age might be too old.[10]
The classification of Nymphaeales and phylogeny within the flowering plants, as of APG III (2009).
This order was not part of the APG II system's 2003 plant classification (unchanged from the APG system of 1998), which instead had a broadly circumscribed family Nymphaeaceae (including Cabombaceae) unplaced in any order. The APG III system did separate the Cabombaceae from the Nymphaeaceae and placed them in the order Nymphaeales together with the Hydatellaceae. The family Hydatellaceae was placed among the monocots in previous systems, but a 2007 study found that the family belongs to the Nymphaeales.[18] In the APG IV system, Hydatellaceae, Cabombaceae and Nymphaeaceae are the three families included in the Nymphaeales.[19]
Some earlier systems, such as Cronquist's system of 1981, often included the Ceratophyllaceae and Nelumbonaceae in the Nymphaeales. Although, the Takhtajan system of 1980 separated the Nelumbonales, the new order was retained alongside the Nymphaeales in the superorder Nymphaeanae.
The Cronquist system placed the Nymphaeales in subclass Magnoliidae, in class Magnoliopsida [=dicotyledons]. In addition, Cronquist included the Ceratophyllaceae and split the family Barclayaceae from the Nymphaeaceae. Under the APG II system, the family Cabombaceae was included within the Nymphaeaceae, but could optionally be recognized separately. As of APG III, the two families are recognized separately.
The Dahlgren system placed the Nymphaeales with the Piperales in superorder Nymphaeanae, within subclass Magnoliideae (dicotyledons). Thorne's 1992 system (and 2000 revision) placed the Nymphaeales as the sole order in the superorder Nymphaeanae within subclass Magnoliideae (=dicotyledons).
^Takhtajan, Armen L. (1980). "Outline of the classification of flowering plants (Magnoliophyta)". The Botanical Review. 46 (3): 225–359. doi:10.1007/BF02861558. S2CID30764910.
^Dahlgren, R.M.T. (1980). "A revised system of classification of angiosperms". Botanical Journal of the Linnean Society. 80 (2): 91–124. doi:10.1111/j.1095-8339.1980.tb01661.x.
^Thorne, R. F. (1992). "Classification and geography of the flowering plants". Botanical Review. 58 (3): 225–348. doi:10.1007/BF02858611. S2CID40348158.
^Thorne, R. F. (2000). "The classification and geography of the flowering plants: Dicotyledons of the class Angiospermae". Botanical Review. 66 (4): 441–647. doi:10.1007/BF02869011. S2CID43430454.
Further reading
Michael G. Simpson. Plant Systematics. Elsevier Academic Press. 2006.
Thomas N. Taylor, Edith L. Taylor, and Michael Krings. 2008. Paleobotany: The Biology and Evolution of Fossil Plants, Second Edition. Academic Press (an imprint of Elsevier): Burlington MA, USA. ISBN978-0-12-373972-8