Caryophyllales


Caryophyllales is a diverse and heterogeneous order of flowering plants with well-known members including cacti, carnations, beets, quinoa, spinach, amaranths, pigfaces and ice plants, oraches and saltbushes, goosefoots, sundews, Venus flytrap, tropical pitcher plants, Malabar spinach, bougainvilleas, four o'clock flowers, buckwheat, knotweeds, rhubarb, sorrels, purslanes, jojoba, and tamarisks. Many members are succulent, having fleshy stems or leaves.
The betalain pigments are unique in plants of this order and occur in all its core families with the exception of Caryophyllaceae and Molluginaceae. Noncore families, such as Nepenthaceae, instead produce anthocyanins. In its modern definition, the order encompasses a whole new group of families that never synthesize betalains, among which several families are carnivorous.
According to the molecular clock calculations, the lineage that led to Caryophyllales split from other plants about 111 million years ago.

Description

The members of Caryophyllales include about 6% of eudicot species. This order is part of the core eudicots. Currently, the Caryophyllales contains 37 families, 749 genera, and 11,620 species The monophyly of the Caryophyllales has been supported by DNA sequences, cytochrome c sequence data and heritable characters such as anther wall development and vessel-elements with simple perforations.

Taxonomy and Phylogeny

As with all taxa, the circumscription of Caryophyllales has changed within various classification systems. All systems recognize a core of families with centrospermous ovules and seeds. More recent treatments have expanded the Caryophyllales to include many carnivorous plants.
Systematists were undecided on whether Caryophyllales should be placed within the rosid complex or sister to the asterid clade. The possible connection between sympetalous angiosperms and Caryophyllales was presaged by Bessey, Hutchinson, and others; as Lawrence relates: "The evidence is reasonably conclusive that the Primulaceae and the Caryophyllaceae have fundamentally the same type of gynecia, and as concluded by Douglas '...the vascular pattern and the presence of locules at the base of the ovary point to the fact that the present much reduced flower of the Primulaceae has descended from an ancestor which was characterized by a plurilocular ovary and axial placentation. This primitive flower might well be found in centrospermal stock as Wernham, Bessy, and Hutchinson have suggested.' "
Caryophyllales is separated into two suborders: Caryophyllineae and Polygonineae. These two suborders were formerly recognized as two orders, Polygonales and Caryophyllales.

Angiosperm Phylogeny Group (APG)

As of the APG IV system of classification the order Caryophyllales contains 38 families:
26 of the 38 families were included in the original APG system and the remaining 12 were added during later revisions: three in the APG II system, five in the APG III system, and four in the APG IV system. Families added during APG revisions are so noted above.
Image:Flower dianthus.JPG|thumb|''A flower of Dianthus''

Cronquist

The earlier Cronquist system recognised the order with 12 families:
  • family Achatocarpaceae
  • family Aizoaceae
  • family Amaranthaceae
  • family Basellaceae
  • family Cactaceae
  • family Caryophyllaceae
  • family Chenopodiaceae
  • family Didiereaceae
  • family Nyctaginaceae
  • family Phytolaccaceae
  • family Portulacaceae
  • family Molluginaceae
The difference with the order as recognized by APG lies in the first place in the concept of "order". The APG favours much larger orders and families, and the order Caryophyllales sensu APG should rather be compared to subclass Caryophyllidae sensu Cronquist.
A part of the difference lies with what families are recognized. The plants in the Stegnospermataceae and Barbeuiaceae were included in Cronquist's Phytolaccaceae. The Chenopodiaceae are included in Amaranthaceae by APG.
New to the order are the Asteropeiaceae and Physenaceae, each containing a single genus, and two genera from Cronquist's order Nepenthales.

Earlier circumscriptions

Earlier systems, such as the Wettstein system, last edition in 1935, and the Engler system, updated in 1964, had a similar order under the name Centrospermae.