Houstonia (plant)

Houstonia
Houstonia caerulea
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Gentianales
Family: Rubiaceae
Subfamily: Rubioideae
Tribe: Spermacoceae
Genus: Houstonia
L.
Synonyms[1]
  • Poiretia J.F.Gmel. non Vent.
  • Panetos Raf.
  • Chamisme Nieuwl.

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.

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 with 4 lobes, and an inferior ovary. 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.[2] Another 5 species are classified in the genus Stenaria; Houstonia without Stenaria is paraphyletic.[3] Close relatives of the genus are Oldenlandia microtheca and, more distantly, Arcytophyllum.[4]

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.

  1. ^ "World Checklist of Selected Plant Families".
  2. ^ Edward E. Terrell (10 June 1996), "Revision of Houstonia (Rubiaceae-Hedyotideae)", Systematic Botany Monographs, 48, American Society of Plant Taxonomists: 1–118, doi:10.2307/25027862, JSTOR 25027862
  3. ^ Sheri A. Church; Douglas R. Taylor (2005), "Speciation and Hybridization among Houstonia (Rubiaceae) Species: The Influence of Polyploidy on Reticulate Evolution", American Journal of Botany, 92 (8): 1372–80, doi:10.3732/ajb.92.8.1372, PMID 21646157
  4. ^ Groeninckx, I.; Dessein, S.; Ochoterena, H.; Persson, C.; Motley, T.J.; Kårehed, J.; Bremer, B.; Huysmans, S.; Smets, E. (2009). "Phylogeny of the Herbaceous Tribe Spermacoceae (Rubiaceae) Based on Plastid DNA Data". Annals of the Missouri Botanical Garden. 96 (1): 109–32. doi:10.3417/2006201. S2CID 56042261.