Bacopa, Aublet, 1775

Sosa, María De Las Mercedes, Moroni, Pablo & O’Leary, Nataly, 2018, A taxonomic revision of the genus Bacopa (Gratioleae, Plantaginaceae) in Argentina, Phytotaxa 336 (1), pp. 1-27 : 3

Key to the taxa of Bacopa that occur in Argentina

1. Stems entirely glabrous, leaf blade obovate ..................................................................................................................... B. monnieri

- Stems variously pubescent, leaf blade elliptic, ovate, orbicular or oblong, exceptionally pinnatisect or pinnatifid.........................2

2. Stems strigose, villose, scabrid or hispid, mostly densely pubescent................................................................................................3

- Stems sub-glabrous, or slightly strigose or puberulous......................................................................................................................7

3. Stems erect; flowers arranged in terminal racemose inflorescences; corolla orange, pink or red .................................... B. congesta

- Stems prostrate; flowers axillary, solitary; corolla white, blue, violet or pale blue...........................................................................4

4. Style entire .................................................................................................................................................................... B. salzmannii

- Style bifid...........................................................................................................................................................................................5

5. Ovary with a ring of long bristles, bracteoles present or absent, stems densely hispid villose ................................... B. serpyllifolia

- Ovary glabrous, bracteoles absent, stems strigose, sometimes villose, denser towards the apex.....................................................6

6. Stamens 4; floral pedicel longer than 10 mm ................................................................................................................... B. australis

- Stamens 2; floral pedicels less than 5 mm long .................................................................................................................... B. repens

7. Bracteoles absent...............................................................................................................................................................................8

- Bracteoles present...............................................................................................................................................................................9

8. Calyx glabrous ............................................................................................................................................................. B. rotundifolia

- Calyx slightly puberulous ..................................................................................................................................................... B. dubia

9. Leaves 3 – 5 verticillate, dimorphic: submerged leaves with pinnatisect or pinnatifid blade, aerial leaves with pinnatifid to entire blade ............................................................................................................................................................................... B. verticillata

- Leaves opposite, not dimorphic........................................................................................................................................................10

10. Stems sub glabrous; flowers sessile or with a brief pedicel up to 2 mm long; capsule with acute apex ................. B. monnierioides

- Stems slightly strigose or puberulous; flowers with a pedicel longer than 4 mm long; capsule with rounded apex......................11

11. Leaf blades oblong or narrow ovate, base auriculate; bracteoles 0.8–1 mm long .................................................. B. paraguariensis

- Leaf blades ovate, base acute; bracteoles 3 – 4 mm long ..................................................................................... B. scabra var. scabra