Croft's Bluet

Houstonia croftiae Britt. & Rusby, Trans. N. Y. Acad. Sci. 7:
10. 1887.
Spreading annual, much branched, the branches slender, 1-4 cm. long, sparsely hirtellous, the internodes equaling or shorter than the leaves; stipules minute, scarious, laciniate-dentate; leaves opposite, sessile or nearly so, oblanceolate or linear-oblanceolate, 5-15 mm. long,
2.5 mm. wide or narrower, obtuse or acute, usually hirsutulous on the costa above, glabrous
beneath, ciliate near the base, 1 -nerved, the margins revolute; flowers axillary, the pedicels
shorter than the calyx; hypanthium about 1 mm. long, hirtellous; calyx-lobes lance-oblong,
acute; corolla salverform, 3 mm. long, white; capsule depressed-globose, subdidymous, 2-3
mm. broad, about one fourth inferior, hirtellous; seeds cymbiform, rounded-oval, black, with
a short hilar ridge.
Type locality: San Diego, Duval County, Texas. Distribution: Known only from the type locality.

Houstonia croftiae, the South Texas bluet or Croft's bluet, is a species of plants in the family Rubiaceae. It is known only from 9 counties in southern Texas: Hidalgo, Starr, Zapata, Webb, La Salle, Duval, Jim Wells, Refugio and San Patricio).