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Houstonia caerulea

Bluet, Quaker ladies

Plant Details

Common Name: Bluet, Quaker ladies
Family: Rubiaceae (madder family)
Mature Height: <6"
Sun Requirement: Sun to part shade, Part shade to shade
Moisture Requirement: Dry - medium, Medium - moist, Moist
Flower Color: White, Yellow, Blue
Bloom Time: Spring (May or earlier), Early summer (June - July)
Seed Collection Date: Early summer (June - July)

Houstonia caerulea Azure bluet
Houstonia caerulea Azure bluets
Houstonia caerulea Azure bluet
Houstonia caerulea Azure bluet
Houstonia caerulea Azure bluet

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Houstonia is from new Latin – the plant is named after the Scottish botanist from the 1700s William Houston; caerulea is Latin for dark blue.

Native Habitat

Deciduous woods and moist meadows.

Garden Uses

Bluets are easy to grow and make an attractive addition to rock gardens, crevice gardens, woodland gardens and cottage gardens.


Bluet is a dainty and delicate herbaceous perennial wildflower. The 3” – 6” plants form striking clusters when the flowers open in late spring to early summer. This wildflower has shallow fibrous roots and slender rhizomes, forming tufts. They thrive in lawns, fields along roadsides and in rock crevices.

Leaves and Stems

The leaves are opposite and have smooth margins. Leaves that originate at the base of the stem are large, while the two leaves on the stem are small. The unbranched stems are light green, 4-angled, smooth, and more or less erect. Each stem terminates in 1-2 flowers (usually only one).


Pale blue flowers, 3/8” across, with yellow centers first mature in mid-spring and continue into mid-summer. The flowers have four symmetrically arranged petals. The plant has two types of flowers, the first having long stamens and a short style and the other having a short stamen and a long style. 1/8” Dry fruit splits open to produce small seeds when ripe.


1/8” dry fruits split open to produce small seeds when ripe.

Animal Associates

The flowers attract several species of bees and butterflies.  Bluet is the host plant for the spotted Thyris moth. This plant is moderately resistant to damage from deer.


Plant seeds outside at a shallow depth as soon as they ripen or store, stratify and sow in the spring.

Ethnobotanical Uses

The Cherokee used an infusion of bluet as a cure for bedwetting.

Garden Location

Patio Garden (see garden map)


Native Plant Trust

North Carolina Cooperative Extension Service

Illinois Wildflowers



Plant Profile by Kathy Kling