Rubiaceae
Azure bluet
Houstonia caerulea
- Family
- Rubiaceae
- Genus
- Houstonia
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Common names
By language (2)
- Chinese
- 美耳草
- English
- Azure bluet, Bluet
Synonyms
- Anotis coerulea (L.) G.Don
- Anotis gentianoides (Endl.) Walp.
- Hedyotis brachiata Miq. ex Hook.f.
- Hedyotis caerulea (L.) Hook.
- Hedyotis caerulea f. albiflora (Millsp.) Fosberg
- Hedyotis caerulea f. benkei Fosberg
- Hedyotis caerulea var. faxonorum (Pease & A.H.Moore) Fosberg
- Hedyotis gentianoides Endl.
- Houstonia caerulea f. albiflora Millsp.
- Houstonia caerulea f. caerulea
- Houstonia caerulea var. caerulea
- Houstonia caerulea var. elatior (Michx.) Pursh
- Houstonia caerulea var. faxonorum Pease & A.H.Moore
- Houstonia caerulea var. piersii Barbour
- Houstonia caerulea var. toxonorum Stevens
- Houstonia faxonorum (Pease & A.H.Moore) Fernald
- Houstonia grandiflora Raf.
- Houstonia linnaei Michx.
- Houstonia linnaei var. elatior Michx.
- Houstonia pusilla J.F.Gmel.
- Houstonia serpyllifolia Graham
- Oldenlandia caerulea (L.) A.Gray
- Poiretia erecta J.F.Gmel.
Characteristics
- Growth habit
- Forb/herb
- Lifespan
- Perennial
- In the US and Canada
- Canada: native, Lower 48 states: native, St. Pierre and Miquelon: introduced
Photos
Photo: Jomegat, CC BY-SA 3.0, from Wikimedia Commons 
Photo: -- SB_Johnny, CC BY-SA 4.0, from Wikimedia Commons 
Photo: Ghislain118 http://www.fleurs-des-montagnes.net, CC BY-SA 3.0, from Wikimedia Commons 
Photo: Ghislain118 http://www.fleurs-des-montagnes.net, CC BY-SA 3.0, from Wikimedia Commons 
Photo: Ghislain118 http://www.fleurs-des-montagnes.net, CC BY-SA 3.0, from Wikimedia Commons 
Photo: Ghislain118 https://www.fleurs-des-montagnes.net, CC BY-SA 3.0, from Wikimedia Commons 
Photo: Linda M Morgan, CC BY-SA 3.0, from Wikimedia Commons 
Photo: Dcrjsr, CC BY 3.0, from Wikimedia Commons 
Photo: Dcrjsr, CC BY 3.0, from Wikimedia Commons 
Photo: Fritzflohrreynolds, CC BY-SA 3.0, from Wikimedia Commons 
Photo: Jay Sturner from USA, CC BY 2.0, from Wikimedia Commons 
Photo: vastateparksstaff, CC BY 2.0, from Wikimedia Commons
More in Houstonia
- Venus' prideHoustonia purpureaRubiaceae
- Longleaf summer bluetHoustonia longifoliaRubiaceae
- Canadian summer bluetHoustonia canadensisRubiaceae
- Matted bluetHoustonia humifusaRubiaceae
- Roundleaf bluetHoustonia procumbensRubiaceae
- Tiny bluetHoustonia pusillaRubiaceae
- Red bluetHoustonia rubraRubiaceae
- Thymeleaf bluetHoustonia serpyllifoliaRubiaceae
- Pygmy bluetHoustonia wrightiiRubiaceae
- Needleleaf bluetHoustonia acerosaRubiaceae
- Southern bluetHoustonia micranthaRubiaceae
- Correll's bluetHoustonia correlliiRubiaceae
Sources: classification, synonyms from World Flora Online Plant List (2026-06, CC0 1.0); common names, popularity from Wikidata (2026-10-26, CC0 1.0); common names, US characteristics from USDA PLANTS Database (2025-05-29, CC0 1.0). About our plant data.