Calandrinia is a genus of flowering plants in the family Montiaceae (order Caryophyllales), commonly known as purslanes and redmaids. It comprises approximately 37 accepted species of annual and perennial herbs distributed across the Americas, with the core range spanning western and southern South America, Central America, and western North America. A handful of species have been introduced beyond their native range to Australia, New Zealand, southern Africa, Asia, and Europe.
Plants in the genus grow with a sprawling or erect habit. Leaves are mostly basal and may be arranged alternately or oppositely along the stem. Flowers are borne in cymes and typically carry five petals, though the count can range from four to eleven. Flower colour spans white, pink, red, purple, and occasionally yellow, making many species ornamentally attractive.
The genus was erected in 1823 by German botanist Carl Sigismund Kunth and named in honour of Jean Louis Calandrini (1703–1758), a Swiss-Genevan botanist. Calandrinia was originally placed in the family Portulacaceae but has since been reclassified to the more narrowly circumscribed Montiaceae. The taxonomy of the genus has been substantially revised: more than 60 species native to Australia and New Guinea that were long included in Calandrinia are now transferred to the segregate genera Rumicastrum and Parakeelya, following morphological and genomic evidence — first proposed by Australian taxonomist Roger Carolin in 1987 — that the Australian and American lineages are not closely related. The appropriate genus name for the Australian species remains debated; Plants of the World Online accepts Rumicastrum, while a competing proposal to use Parakeelya (derived from South Australian and Central Desert Indigenous names) has not yet been formally resolved.
Etymology
The genus name Calandrinia honours Jean Louis Calandrini (1703–1758), a Swiss botanist from Geneva. The genus was formally described in 1823 by German botanist Carl Sigismund Kunth.
Distribution
Calandrinia species are native to the Americas, with the greatest diversity in western and southern South America; the range extends through Central America to western North America. Several species have been introduced to Australia, New Zealand, southern Africa, parts of Asia, and Europe.
Taxonomy Notes
Calandrinia was originally placed in Portulacaceae but is now classified in the family Montiaceae, order Caryophyllales. More than 60 formerly included Australian and New Guinean species have been transferred to Rumicastrum or Parakeelya, following evidence from morphological and genomic studies that the American and Australian lineages represent two separate evolutionary groups. The appropriate genus name for the Australian segregate remains unresolved: Plants of the World Online accepts Rumicastrum, but a proposal to use Parakeelya — a name with Indigenous Australian roots — is still under consideration.
