Quaker Ladies
Houstonia caerulea
Madder family (Rubiaceae)

Description: This small perennial wildflower is about 3-6" tall, consisting of a rosette of basal leaves and one or more flowering stems with opposite leaves. The basal leaves are about " long, medium green, elliptic or oblanceolate in shape, glabrous, and smooth along their margins. The unbranched stems are light green, 4-angled, glabrous, and more or less erect. The opposite leaves, which are widely spaced along each stem, are " long or less, medium green, linear-elliptic in shape, glabrous, sessile, and smooth along their margins. Each stem terminates in 1-2 flowers (usually only one). The flowers have slender pedicels that are light green and glabrous. Individual flowers are 3/8" (10 mm.) across, consisting of a light green tubular calyx with 4 linear lobes, a narrowly tubular corolla with 4 petal-like lobes, 4 stamens, and a pistil with a single style that is bifurcated at its tip. The petal-like lobes of the corolla are pale blue-violet (rarely white), ovate in shape, and widely spreading. At the base of the lobes, the corolla is yellow.

Two types of flowers are produced: those with long stamens and a short style, and those with short stamens and a long style. Regardless of the flower type, both stamens and style are inserted within the corolla or barely visible at its mouth. The blooming period occurs during the late spring and lasts about 3 weeks. The flowers are replaced by 2-lobed seed-capsules about 1/8" (3 mm.) across. The capsule contains several small seeds with minute pebbly surfaces (when viewed under magnification). This wildflower has shallow fibrous roots and slender rhizomes, forming tufts of flowering plants.

Cultivation: The preference is full or partial sun, moist to dry-mesic conditions, and either sandy or thin rocky soil that is somewhat acidic. Most growth and development occurs during the spring. This wildflower will adapt to rock gardens.

Range & Habitat: The native Quaker Ladies is found along the easternmost tier of counties and scattered areas of southern Illinois (see Distribution Map). It is an uncommon species in this state. Habitats include sand prairies, sandy savannas, sandy paths in wooded areas, sandstone glades and ledges, and damp rocky areas along upland streams. This wildflower occurs in higher quality habitats with sparse ground vegetation.

Faunal Associations: The flowers of Quaker Ladies attract Little Carpenter bees (Ceratina spp.), Green Metallic bees and other Halictid bees, bee flies (Bombyliidae), and small butterflies. Blanchon (1901) observed the butterfly Boloria bellona (Meadow Fritillary) as a frequent visitor of the flowers. Both nectar and pollen are available as floral rewards. According to Covell (1984/2005), Houstonia spp. (Bluets) are host plants for caterpillars of the moth Thyris maculata (Spotted Thyris). It is doubtful that mammalian herbivores make much use of the foliage of Quaker Ladies, considering its low stature and sparseness.

Photographic Location: A mossy path in a sandy woodland in NW Ohio near the Oak Openings region.

Comments: This wildflower is dainty, delicate, and wonderful. It is perhaps the most aesthetically pleasing of the small wildflowers in its genus. In Illinois, Quaker Ladies can be distinguished from other Bluets (Houstonia spp.) by the patch of yellow at the center of its corolla. In addition, the opening of its corolla is more narrow than most Bluets and the lobes of its corolla are relatively larger in size and more widely spreading. A species that does not occur within the state, Mountain Bluets (Houstonia serpyllifolia), shares these characteristics with Quaker Ladies. Mountain Bluets differs by having oval-shaped basal leaves that creep across the ground. This latter species is found primarily in the Appalachian mountains. Other common names of Houstonia caerulea are Azure Bluets and Innocence.