Houstonia subviscosa (A. Gray) A. Gray, nodding bluet. Annual, slender–taprooted, wispy, 1–stemmed at base, not rosetted, branches forking at nodes and ± spreading, 3— < 20 cm tall; shoots with only tiny cauline leaves, stiff–puberulent.
Stems ± 4–sided and narrowly 4–ridged, to 0.5 mm diameter, internodes < 20 mm long, with pulvinus at base of each basal internode, aging reddish and ridges colorless.
Leaves opposite decussate, simple, subsessile, with stipules fusing across nodes; stipules papery, between leaves at node (interpetiolar), triangular in outline; petiole slender, to 1 mm long; blade linear, 6—13 × < 1 mm, entire, acute at tip, 1–veined with midrib raised on lower surface, sparsely puberulent.
Inflorescence flower solitary at node, axillary to 1 leaf, stiff–puberulent; pedicel short increasing 2—3× in fruit.
Flower bisexual, ± radial, ca. 1.5 mm across; sepals 4, 2 on sides and 2 on ends, triangular, erect, 1.1—1.3 mm long, green with colorless midridge, with numerous stiff, short hairs; corolla 4–lobed, white; tube cylindric, 1 × 0.4 mm, outer surface glabrous, inner surface with several short hairs below anthers; lobes spreading, ovate, ± 0.7 mm long; stamens 4, attached on corolla tube ca. 0.4 mm below sinuses; filaments erect, 0.3—0.35 mm long, white; anthers dorsifixed, dithecal, short–exserted, 0.35 mm long, cream, longitudinally dehiscent; pollen pale yellow; pistil 1; ovary inferior, inconspicuously 2–lobed, green, 2–chambered, each chamber with several ovules; style short–exserted, ca. 1.8 mm long, white, 2–branched 0.25—0.3 mm from tip, thick–cylindric 0.2 mm diameter at base, the branches stigmatic, at level of anthers, appressed in bud later spreading and aging reddish.
Fruit capsule, 2–lobed dehiscing lengthwise on top, ± 12–seeded, ca. 3 × 1.5 × 1.5 mm, seeds on surface of green fleshy placentae; sepals connected by weak ledges.
Seed limpetlike, 0.85—1 mm long, purplish red, minutely rough, on concave side with longitudinal ridge (raised embryo axis) and cupped wings.
A. C. Gibson