''Houstonia'' (bluet) is a genus of plants in the family Rubiaceae. Many species were formerly classified, along with other genera since segregated elsewhere, in a more inclusive genus ''

Hedyotis ''Hedyotis'' (starviolet) is a genus of flowering plants in the family Rubiaceae. Many species of this genus such as ''Hedyotis biflora, H. corymbosa'' and ''H. diffusa'' are well known medicinal plants. ''Hedyotis'' is native to tropical a ...

''. Bluets are often small and delicate. For example, ''H. rosea'' may grow only one inch tall. Some species are single stemmed and others have multiple stems in bunches. Flowers are blue, purple, lavender, white, or rose, often with shades of one color present in an individual population. Flowers have 4 sepals, colloquially denominated "petals", a salverform

corolla Corolla may refer to: *Corolla (botany), the petals of a flower, considered as a unit *Toyota Corolla, an automobile model name * Corolla (headgear), an ancient headdress in the form of a circlet or crown * ''Corolla'' (gastropod), a genus of moll ...

with 4 lobes, and an inferior

ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...

. Some species exhibit heterostyly. The fruit is an often roughly cordate capsule enclosing many seeds and which usually dehisces via a suture across its apex. ''Houstonia'' consists of 20 species native to

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. Another 5 species are classified in the genus '' Stenaria''; ''Houstonia'' without ''Stenaria'' is

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 ...

. Close relatives of the genus are '' Oldenlandia microtheca'' and, more distantly, ''

Arcytophyllum ''Arcytophyllum'' is a genus of flowering plants in the family Rubiaceae. The genus contains 18 species, distributed from New Mexico to Bolivia. Description Members of this genus are shrubs or dwarf shrubs that occupy mountainous habitats. Thei ...

''. Its members superficially resembles species of the genus '' Myosotis'' (Forget-me-nots), but are distinguished from the latter by having only 4 sepals (petals) instead of 5.

Species

Species accepted as of May 2014 are:Kew World Checklist of Selected Plant Families
/ref> # '' Houstonia acerosa'' (A.Gray) Benth. & Hook.f.:

Chihuahua Chihuahua may refer to: Places *Chihuahua (state), a Mexican state **Chihuahua (dog), a breed of dog named after the state **Chihuahua cheese, a type of cheese originating in the state **Chihuahua City, the capital city of the state **Chihuahua Mun ...

Coahuila Coahuila (), formally Coahuila de Zaragoza (), officially the Free and Sovereign State of Coahuila de Zaragoza ( es, Estado Libre y Soberano de Coahuila de Zaragoza), is one of the 32 states of Mexico. Coahuila borders the Mexican states of N ...

Nuevo León Nuevo León () is a state in the northeast region of Mexico. The state was named after the New Kingdom of León, an administrative territory from the Viceroyalty of New Spain, itself was named after the historic Spanish Kingdom of León. With a ...

, Tamaulipas, and

San Luis Potosí San Luis Potosí (), officially the Free and Sovereign State of San Luis Potosí ( es, Estado Libre y Soberano de San Luis Potosí), is one of the 32 states which compose the Federal Entities of Mexico. It is divided in 58 municipalities and i ...

and Texas and New Mexico, United States # ''

Houstonia biloba Houstonia may refer to: * Houstonia, Missouri, a city in Missouri * ''Houstonia'' (plant), a genus of flowering plants, belonging to the madder family (Rubiaceae) * ''Houstonia'' (magazine), a magazine * Houstonia (insect), a genus of wasp, belo ...

'' Raf. # ''

Houstonia caerulea ''Houstonia caerulea'', commonly known as azure bluet, Quaker ladies, or bluets, is a perennial species in the family Rubiaceae. It is native to eastern Canada (Ontario to Newfoundland) and the eastern United States (Maine to Wisconsin, south to ...

'' L. (azure bluet): eastern Canada and eastern United States # ''

Houstonia canadensis ''Houstonia canadensis'', common name Canadian summer bluet, is a plant species native to the United States and Canada. It has been reported from Ontario, Saskatchewan, New York, Pennsylvania, Ohio, Indiana, Illinois, Michigan, Kentucky, Missouri ...

'' Willd. ex Roem. & Schult. (Canadian summer bluet): Ontario and Saskatchewan, Canada and eastern United States # ''

Houstonia cervantesii Houstonia may refer to: * Houstonia, Missouri, a city in Missouri * ''Houstonia'' (plant), a genus of flowering plants, belonging to the madder family (Rubiaceae) * ''Houstonia'' (magazine), a magazine * Houstonia (insect), a genus of wasp, belo ...

'' Terrell # ''

Houstonia chlorantha Houstonia may refer to: * Houstonia, Missouri, a city in Missouri * ''Houstonia'' (plant), a genus of flowering plants, belonging to the madder family (Rubiaceae) * ''Houstonia'' (magazine), a magazine * Houstonia (insect), a genus of wasp, belo ...

'' Bertol. # ''

Houstonia correllii ''Houstonia correllii'', the Zapata County bluet, or Correll's bluet, is a species of plants in the Rubiaceae. It is known only from Zapata County in southern Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a stat ...

'' (W.H.Lewis) Terrell (Correll's bluet): Texas, United States # ''

Houstonia croftiae ''Houstonia croftiae'', the South Texas bluet or Croft's bluet, is a species of plants in the family Rubiaceae. It is known only from 9 counties in southern Texas: Hidalgo, Starr, Zapata, Webb, La Salle, Duval Duval is a surname, literally tr ...

'' Britton & Rusby (Croft's bluet): Texas, United States # '' Houstonia humifusa'' (Engelm. ex A.Gray) A.Gray (matted bluet): New Mexico,

Oklahoma Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a U.S. state, state in the South Central United States, South Central region of the United States, bordered by Texas on the south and west, Kansas on the nor ...

, and Texas, United States # ''

Houstonia longifolia ''Houstonia longifolia'', commonly known as long-leaved bluet or longleaf summer bluet, is a perennial plant in the family Rubiaceae. It can be found throughout most of the Eastern United States and Canada. It has been reported from every state e ...

'' Gaertn. (longleaf summer bluet): eastern and central United States and central Canada # ''

Houstonia micrantha ''Houstonia micrantha'', the southern bluet, is a plant species in the coffee family. It is native to the south-central United States where it has been found in Texas, Louisiana, Arkansas, Mississippi, southern Missouri, Alabama, western Tennes ...

'' (Shinners) Terrell (southern bluet): central and southeastern United States # '' Houstonia nuttalliana'' Fosberg # '' Houstonia ochroleuca'' Raf. # ''

Houstonia ouachitana ''Houstonia ouachitana'', the Ouachita bluet, is a species of plants in the coffee family. It is endemic to the Ouachita Mountains of Arkansas and Oklahoma Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) ...

'' (E.B.Sm.) Terrell (Ouachita bluet): Arkansas and

, United States # '' Houstonia palmeri'' A.Gray:

and

# '' Houstonia parviflora'' Holz. ex Greenm. (Greenman's bluet): Texas, United States # '' Houstonia procumbens'' (J.F.Gmel.) Standl. (roundleaf bluet): Louisiana, Mississippi, Alabama, Georgia, Florida, and South Carolina, United States # '' Houstonia prostata'' Brandegee # '' Houstonia purpurea'' L. (Venus' pride): eastern and central United States # '' Houstonia pusilla'' Schöpf (tiny bluet): central and southeastern United States and Arizona, United States # '' Houstonia reticulata'' Raf. # '' Houstonia rosea'' (Raf.) Terrell (rose bluet): south-central United States # ''

Houstonia rubra ''Houstonia rubra'', the red bluet, is a plant species in the Rubiaceae. It is a small herb with white to pink to red to reddish-purple flowers, native to the southwestern United States and northern and central Mexico: Coahuila, Nuevo León, ...

'' Cav. (red bluet): northern and central Mexico as far south as

Puebla Puebla ( en, colony, settlement), officially Free and Sovereign State of Puebla ( es, Estado Libre y Soberano de Puebla), is one of the 32 states which comprise the Federal Entities of Mexico. It is divided into 217 municipalities and its cap ...

and Arizona, New Mexico, Texas, and Utah, United States # '' Houstonia serpyllifolia'' Michx. (creeping, mountain, thymeleaft, and Appalachian bluet): Appalachian Mountains from Pennsylvania to Georgia, United States # '' Houstonia sharpii '' Terrell: Hidalgo and Veracruz # '' Houstonia spellenbergii'' (G.L.Nesom & Vorobik) Terrell:

# '' Houstonia subviscosa'' (C.Wright ex A.Gray) A.Gray (nodding bluet): Texas, United States # '' Houstonia teretifolia '' Terrell:

# ''

Houstonia wrightii ''Houstonia wrightii'', the pygmy bluet, is a plant species in the Rubiaceae. It is native to the south-western United States ( Arizona, New Mexico, western Texas) and northern Mexico (Chihuahua, Sonora Sonora (), officially Estado Libre ...

'' A.Gray (pygmy bluet): Arizona, New Mexico, and Texas, United States and Mexico

References

{{Taxonbar, from=Q9005036 Rubiaceae genera Flora of North America