Diapensiaceae is a small

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s, which includes 15

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

in 6

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

. The genera include '' Berneuxia'' Decne. (1 species), '' Diapensia'' L. (5 species), '' Galax'' Sims (1 species), '' Pyxidanthera'' Michx. (2 species), '' Shortia'' Torr. & A.Gray (4 species), and '' Schizocodon'' Siebold & Zucc. (2 species). Members of this family have little economic importance; however, some members are cultivated by florists.

Taxonomy

Past literature classified Diapensiaceae as an old family, without defining the meaning of old. The name '' Diapensia'' was given to ''Diapensia lapponica'' by

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

. Previously, it was the Greek name of sanicle. The family, originally including only ''Diapensia lapponica'', was named by Heinrich Friedrich Link in 1829. Concerning the interrelationships in Diapensiaceae, debate still remains regarding the recognition of ''Schizocodon'' and whether it should be separate from ''Shortia''. However, recent molecular studies support the split of the two genera. Additionally, recognition of species within the genera has been debated. Within the genus ''Pyxidanthera'', two species have previously been recognized. Recent morphology and molecular work found that the two species do not differ morphologically, gene flow exists between them, and the taxa are not

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

. Over time, various relationships among Diapensiaceae and other angiosperm families have been proposed. Previously, it was placed within the order Rosales, as well as in the Cornales. Diapensiaceae was also placed in an order of its own in the

Cronquist system The Cronquist system is a list of systems of plant taxonomy, taxonomic classification system of angiosperms, flowering plants. It was developed by Arthur Cronquist in a series of monographs and texts, including ''The Evolution and Classification of ...

and by Takhtajan. Recent studies have placed Diapensiaceae as part of the

Ericales The Ericales are a large and diverse order of flowering plants in the asterid group of the eudicots. Well-known and economically important members of this order include tea and ornamental camellias, persimmon, ebony, blueberry, cranberry, l ...

clade, belonging to the “styracoids” (Diapensiaceae,

Styracaceae The Styracaceae are a small family of flowering plants in the order Ericales, containing 12 genera and about 160 species of trees and shrubs. The family occurs in warm temperate and subtropical regions of the Northern Hemisphere. The family is ...

Symplocaceae Symplocaceae is a family of flowering plants in the order Ericales The Ericales are a large and diverse order of flowering plants in the asterid group of the eudicots. Well-known and economically important members of this order include tea ...

). It is estimated that Diapensiaceae diverged from Sytracaceae about 93 million years ago. The family is thought to have originated in the Northern Hemisphere.

Distribution

Family Diapensiaceae members are mostly found in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and

Eastern Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of China, Japan, South Korea, and Taiwan ...

Characteristics

Members of Diapensiaceae are mostly herbs or shrublets.

Flowers Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

have

radial symmetry Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, the face of a human being has a plane of symme ...

, are hypogynous, and have most parts arranged in whorls of 5. The ovary is made of three fused

carpels Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ...

. They have both ectotrophic and endotrophic

mycorrhiza A mycorrhiza (; , mycorrhiza, or mycorrhizas) is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant's rhizosphere, the plant root system and its surroundings. Mycorrhizae play ...

associations.

References

* {{Authority control Ericales Ericales families