Herbs, annual or perennial, emergent or submerged, sometimes rooting from proximal nodes. Stems prostrate or erect, glabrous or slightly hairy. Leaves cauline, opposite [whorled]; petiole obscure or absent; blade fleshy (B. monnieri) or not, not leathery, margins entire, crenate, or serrate. Inflorescences axillary, flowers solitary or in pairs; bracts absent. Pedicels present or absent; bracteoles present [absent]. Flowers bisexual; sepals 4 or 5, distinct, outer wider than inner, ovate, lanceolate, or oblong, calyx radially or bilaterally symmetric, campanulate; corolla white (sometimes with yellow throat), pink, or violet-blue, radially or bilaterally (B. repens) symmetric, regular or weakly bilabiate, rotate or campanulate, rarely tubular, tube base not spurred or gibbous, throat not densely pilose internally, lobes 4 or 5, abaxial 2 or 3, adaxial 2; stamens 2–4, adnate to corolla, didynamous or equal, filaments glabrous; staminode 0; ovary 2-locular, placentation axile; stigmas peltately flattened and semicapitate. Fruits capsules, dehiscence septicidal-loculicidal or loculicidal. Seeds 80–120, brownish black, ellipsoid to cylindric, reticulate, wings absent. × = 14.

Distribution

North America, Mexico, West Indies, Central America, South America, s Europe, Asia, Africa, Indian Ocean Islands (Madagascar), Australia.

Discussion

Species ca. 70 (7 in the flora).

Bacopa laxiflora (Bentham) Wettstein ex Edwall, native to Central America and South America, has been introduced to Mexico and may be expected in the flora area. Plants of B. laxiflora resemble B. monnieri; they differ by erect stems and acute leaf blade apices.

Selected References

Barrett, S. C. H. and J. L. Strother. 1978. Taxonomy and natural history of Bacopa (Scrophulariaceae) in California. Syst. Bot. 3: 408–419.

Schuyler, A. E. 1989. Intertidal variants of Bacopa rotundifolia and B. innominata in the Chesapeake Bay drainage. Bartonia 55: 18–22.

Lower Taxa

Bacopa caroliniana, Bacopa egensis, Bacopa eisenii, Bacopa innominata, Bacopa monnieri, Bacopa repens, Bacopa rotundifolia

Key

1	Leaf blades 1-nerved.	Bacopa monnieri
1	Leaf blades (3–)5–9+-nerved.	> 2
2	Plants aromatic; bracteoles present; corollas violet-blue with violet-blue throats.	Bacopa caroliniana
2	Plants not aromatic; bracteoles absent; corollas white with yellow or white throats or pink with pink throats.	> 3
3	Leaf blade bases narrowly cuneate.	> 4
4	Leaf blade margins crenate.	Bacopa egensis
4	Leaf blade margins entire.	Bacopa repens
3	Leaf blade bases broadly cuneate to truncate.	> 5
5	Pedicels 6–10 mm; corollas 2–5 mm, white with white throats.	Bacopa innominata
5	Pedicels 9–51 mm; corollas 5–14 mm, white with yellow throats.	> 6
6	Pedicels 9–15 mm; corollas 5–10 mm.	Bacopa rotundifolia
6	Pedicels 17–51 mm; corollas 10–14 mm.	Bacopa eisenii