Biology:Ranunculales

Short description: Basal order of flowering plants in the eudicots

Ranunculales Temporal range: 124–0 Ma PreЄ Є O S D C P T J K Pg N Early Cretaceous–Recent
Ranunculus repens
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Order:	Ranunculales Juss. ex Bercht. & J.Presl
Families
See text

Ranunculales is an order of flowering plants. Of necessity it contains the family Ranunculaceae, the buttercup family, because the name of the order is based on the name of a genus in that family. Ranunculales belongs to a paraphyletic group known as the basal eudicots. It is the most basal clade in this group; in other words, it is sister to the remaining eudicots. Widely known members include poppies, barberries, hellebores, and buttercups.

Taxonomy

The Angiosperm Phylogeny Group recognized seven families in Ranunculales in their APG III system, published in 2009. In the preceding APG II system, they offered the option of three segregate families as shown below.

• order Ranunculales

  family Berberidaceae

  family Circaeasteraceae

  [+ family Kingdoniaceae ]

  family Eupteleaceae

  family Lardizabalaceae

  family Menispermaceae

  family Papaveraceae

  [+ family Fumariaceae ]

  [+ family Pteridophyllaceae ]

  family Ranunculaceae

Note: "+ ..." = optionally separate family (that may be split off from the preceding family).

Under this definition, well-known members of Ranunculales include buttercups, clematis, columbines, delphiniums, and poppies.

A phylogeny of Ranunculales was published in 2009, based on molecular phylogenetic analysis of DNA sequences. The authors of this paper revised the subfamilies and tribes of the order. This is reflected in the subsequent revision of the APG, APG IV (2016).

The analysis revealed that the order consisted of three clades, Eupteleaceae, Papaveraceae and a third clade, considered to be the "core" Ranuculales, consisting of the remaining five families. The phylogeny of the families is shown in the cladogram.

Cladogram of Ranunculales families

Ranunculales     Eupteleaceae       Papaveraceae         Circaeasteraceae     Lardizabalaceae         Menispermaceae       Berberidaceae     Ranunculaceae

Evolution

The fossil form Leefructus, described in 2011, has been recognized as a member of this order. Leefructus mirus shows fully developed leaves; stem and flower that are very similar in structure to those of the modern buttercups. The fossil is dated to 125 million years old and it not only proves that Ranunculales is an ancient group of eudicots but demonstrates that the whole angiosperm clade may be older than expected. The structure of the plant and its age may lead to a new approach regarding the field that studies the evolution of flowering plants. The fact that Leefructus shows a well-developed structure similar to modern ranunculids suggests that this group of eudicots may have developed earlier than the age of the fossil.

Another fossil has been described with the name Teixeiraea, also from the Cretaceous.

History

Historically the term Ranales was used to include the Ranunculaceae and related families, as described by Bentham and Hooker. This became replaced with Ranunculales by Melchior in 1964.

The Cronquist system (1981) also recognised the order, but placed it in the subclass Magnoliidae, in class Magnoliopsida [= dicotyledons]. It used this circumscription:

• order Ranunculales

  family Ranunculaceae

  family Circaeasteraceae

  family Berberidaceae

  family Sargentodoxaceae

  family Lardizabalaceae

  family Menispermaceae

  family Coriariaceae

  family Sabiaceae

In the Cronquist system, the Papaveraceae and Fumariaceae (including the plants in the optional family Pteridophyllaceae) were treated as a separate order Papaverales, placed in this same subclass Magnoliidae. The Cronquist circumscription of Ranunculales is now known to be polyphyletic. Sabiaceae is in a clade of basal eudicots separate from Ranunculales. Coriariaceae is now placed in the order Cucurbitales.

Bibliography

• 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. 
• 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. 
• Wang, Wei; Lu, An-Ming; Ren, Yi; Endress, Mary E.; Chen, Zhi-Duan (January 2009). "Phylogeny and classification of Ranunculales: Evidence from four molecular loci and morphological data". Perspectives in Plant Ecology, Evolution and Systematics 11 (2): 81–110. doi:10.1016/j.ppees.2009.01.001. 

External links

• NCBI Taxonomy Browser

Wikidata ☰ Q21021 entry