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Creeping Bluet, Mountain Bluet, Thymeleaf Bluet, Appalachian Bluet, Michaux’s Bluets - Houstonia serpyllifolia


Family: Rubiaceae – Madder family Genus Common Name: Bluets Native Status: Native
Houstonia serpyllifolia - Creeping Bluet, Mountain Bluet, Thymeleaf Bluet, Appalachian Bluet, Michaux’s Bluets. There are about 18 species of Houstonia found in North America, mostly in the east and the south, with Texas having the honor of the most species. Houstonia serpyllifolia has a relatively narrow distribution, found in the Appalachian Mountains from Pennsylvania (perhaps historically only) south to extreme northeast Georgia and western South Carolina. It is Rare (or Extirpated) in Pennsylvania, protected as a State Endangered Species in Kentucky, and is on the State Watch List in Maryland.

This is normally a late spring through early summer blooming species, but these were photographed in a south-facing rock bluff at about 6000' in September.

Found in:
GA, KY, MD, NC, PA, SC, TN, VA, WV

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Distribution of Houstonia serpyllifolia in the United States and Canada:
USDA Plants Distribution Map temporarily unavailable.
Blue=Native; Grey=Introduced

Map from USDA Plants Database:
USDA, NRCS. 2009. The PLANTS Database (http://plants.usda.gov, 19 Jan 2017). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

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Site: Clingman’s Dome, GSMNP, Swain County, NC Date: 2013-September-23Photographer: Gerald C. Williamson
Nikon D7000
Tamron SP 90MM f/2.8 AF Macro
As with most bluets, the blossom of Houstonia serpyllifolia has 4 spreading lobes. The corolla is a blue-violet with a yellow eye at the opening of the narrow corolla tube.
Houstonia serpyllifolia

Site: Clingman’s Dome, GSMNP, Swain County, NC Date: 2013-September-23Photographer: Gerald C Williamson
Nikon D7000
Tamron SP 90MM f/2.8 AF Macro
The flower of Houstonia serpyllifolia is very similar to that of Houstonia caerulea (Quaker Ladies), but is usually a brighter blue, and Houstonia serpyllifolia blossoms have a hairy throat. The flowers are usually less than about 1 / 2 inch across, here shown next to the tip of a car key.
Click on the photo for a larger image
Houstonia serpyllifolia

Site: Clingman’s Dome, GSMNP, Swain County, NC Date: 2013-September-23Photographer: Gerald C Williamson
Nikon D7000
Tamron SP 90MM f/2.8 AF Macro
Mountain Bluet grows from branching creeping stems (Creeping Bluet is another common name.) The stems are smooth, and have erect branches growing up to 8 inches high. The tiny leaves are roundish, up to .3 inch long, and on short petioles. These creeping, foliate stems are a key difference with the similar looking Houstonia caerulea.
Click on the photo for a larger image
Houstonia serpyllifolia

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All content except USDA Plants Database map Copyright Gerald C. Williamson 2017
Photographs Copyrighted by the named photographer