Herbs or small shrubs, usually perennial. Stems green, brown, or purple, glabrous or hispid-hirsute, with or without glandular trichomes or long, jointed hairs; thorns occasionally bearing small leaves toward tips. Leaf blades ovate, lanceolate, or linear, occasionally orbiculate, pin­nately veined, base attenuate, acute, round, or obtuse, margins entire or serrulate, often undulate, apex acuminate to acute, surfaces glabrous or densely pubescent, sometimes gland-dotted, with or without glandular trichomes or long, jointed hairs, occasionally pubescent only along main veins. Inflorescences terminal or axillary, pedunculate, highly branched or unbranched. Flowers: sepals lanceolate or ovate, margins entire, surfaces glabrous or hispid-hirsute, with or without glandular trichomes or long, jointed hairs; corolla blue or white, campanulate; anthers pale pink, white, or blue; filaments white or blue, abruptly dilated at base, glabrous; pollen white or yellow; ovary green or blue, globose or subglobose, proximal 1/2 glabrous, distal 1/2 glabrous, puberulent, or glandular-pubescent; styles white, brown, or blue, often curved inward to summits, glabrous, puberulent, or glandular-pubescent (especially at base); stigmas funnelform. Capsules brown or purple, globose or ovoid, occasionally truncated at style bases, 3–7 × 2.5–7 mm, proximal 1/2 glabrous, distal 1/2 glabrous, puberulent, or glandular-pubescent. Seeds tan to dark brown, ovoid to cylindric, symmetric or occasionally asymmetric, 0.4–0.7 × 0.2–0.4 mm.

Distribution

sc, e United States, Mexico, Central America, South America, s, se Asia, Africa, Indian Ocean Islands (Madagascar), Pacific Islands (Philippines), n Australia.

Discussion

Species 11 (5 in the flora).

Species in the flora area are placed in Hydrolea sect. Hydrolea.

Selected References

None.

Lower Taxa

Hydrolea corymbosa, Hydrolea ovata, Hydrolea quadrivalvis, Hydrolea spinosa, Hydrolea uniflora

Key

1	Inflorescences axillary fascicles.	> 2
2	Stems and sepals with long, jointed hairs.	Hydrolea quadrivalvis
2	Stems and sepals without long, jointed hairs.	Hydrolea uniflora
1	Inflorescences terminal corymbs or leafy panicles.	> 3
3	Stems pubescent or hispid-hirsute, usually densely covered with glandular trichomes, occasionally glabrous.	Hydrolea spinosa
3	Stems pubescent, sometimes with few glandular trichomes.	> 4
4	Leaf blades ovate, 1–2.5 cm wide, margins entire, surfaces pubescent; styles 10–15 mm.	Hydrolea ovata
4	Leaf blades lanceolate, 0.3–1 cm wide, margins serrulate, surfaces glabrous or pubescent; styles 5–10 mm.	Hydrolea corymbosa