Heliotropiaceae is a

cosmopolitan Cosmopolitan may refer to: Food and drink * Cosmopolitan (cocktail), also known as a "Cosmo" History * Rootless cosmopolitan, a Soviet derogatory epithet during Joseph Stalin's anti-Semitic campaign of 1949–1953 Hotels and resorts * Cosmopoli ...

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

s with approximately 450 species worldwide, though it is concentrated especially in the

tropics The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

and

subtropics The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° north and ...

. There are the following four

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

in the family: * ''

Heliotropium ''Heliotropium'' is a genus of flowering plants in the heliotrope family, Heliotropiaceae. There are around 325 species in this almost cosmopolitan genus, which are commonly known as heliotropes (sg. ). It is highly toxic for dogs and cats. Et ...

(''incl. ''Tournefortia'' L.) * ''

Euploca ''Euploca'' is an almost cosmopolitan genus of plants with around 100 species. It was first described by Thomas Nuttall in 1837. While part of the broadly defined Boraginaceae in the APG IV system from 2016, a revision of the order Boraginales ...

'' Nutt. * ''

Ixorhea ''Ixorhea'' is a genus of flowering plants belonging to the family Boraginaceae Boraginaceae, the borage or forget-me-not family, includes about 2,000 species of shrubs, trees and herbs in 146, to 156 genera with a worldwide distribution. ...

'' Fenzl * '' Myriopus'' Small ''Ixorhea'' is sister to ''Euploca'' and ''Myriopus''. Together they form a clade sister to ''Heliotropium'', which comprises four major clades: ''Heliotropium'' sect. ''Heliothamnus'' I.M.Johnst., Old World ''Heliotropium'', ''Heliotropium'' sect. ''Cochranea'' (Miers) Post & Kuntze, and the ''Tournefortia''-clade, the latter comprising ''Tournefortia'' sect. ''Tournefortia'' and all remaining

New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. 3 ...

species of ''Heliotropium''.

History

Prior to a 2016 revision, Heliotropiaceae was considered a subfamily of the

Boraginaceae Boraginaceae, the borage or forget-me-not family, includes about 2,000 species of shrubs, trees and herbs in 146, to 156 genera with a worldwide distribution. The APG IV system from 2016 classifies the Boraginaceae as single family of the or ...

: Heliotropioideae. Even before that, however, there was already some indication in the field that Heliotropiaceae deserved to be recognized as an independent family. Anatomically, the presence of anatropous

ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...

s in Heliotropiaceae as well as the presence of long suspensors and

endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the embryo and ...

haustoria In botany and mycology, a haustorium (plural haustoria) is a rootlike structure that grows into or around another structure to absorb water or nutrients. For example, in mistletoe or members of the broomrape family, the structure penetrates t ...

in Boraginaceae drove the earliest divide between the two families in the literature. Later, molecular data collected from a variety of families in the Boraginales collectively indicated that the Hydrophyllaceae was

sister A sister is a woman or a girl who shares one or more parents with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to refer to ...

to the Heliotropiaceae, something that rendered the Boraginaceae

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

Morphology

In broad terms, members of the Heliotropiaceae are quite diverse in that they can be small trees, lianas, shrubs, sub-shrubs, or even perennial or annual herbs. However they all have 5-merous,

tetracyclic Tetracyclics are cyclic chemical compounds that contain four interconnected rings of atoms, e.g. Tröger's base. They have various pharmaceutical A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or s ...

flowers and

actinomorphic Floral symmetry describes whether, and how, a flower, in particular its perianth, can be divided into two or more identical or mirror-image parts. Uncommonly, flowers may have no axis of symmetry at all, typically because their parts are spirall ...

corollas. These plants are also characterized by their terminal styles and highly modified stigmatic heads (basal stigma, infertile apex) as well as by their fruits (one or two-seeded mericarpids or drupes). Their conical stigmatic heads are unique and are thus a recognizable

synapomorphy In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...

for this family. Heliotropiaceae mostly have distinctly scorpioid cymose

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

References

{{Taxonbar, from=Q19680787 Asterids Asterid families Heliotropioideae