Belongs within: Plantaginaceae.
The Gratioleae are a primarily tropical and warm-temperate group of plants with opposite leaves, simply racemose inflorescences and flowers bearing two distinct, usually flattened stigmas. Representatives include Limosella, mudworts, a cosmopolitan genus of semi-aquatic annual herbs with stolons (Hickman 1993).
<==Gratioleae
|--HerpestidineaeOP01
| |--Herpestis micranthaC55
| `--Bacopa Aublet 1775 (nom. cons.)OP01, SP56
| | i. s.: B. carolinianaOP01
| | B. eiseniiH93
| | B. floribundaLK14
| | B. innominata (Maza) Alain 1956 (see below for synonymy)L95
| | B. monnieri (L.) Pennell 1946 (see below for synonymy)L95
| | B. repens (Sw.) Wettst. in Engl. & Prantl 1891 (see below for synonymy)L95
| | B. rotundifolia (Pursh) Wettst. 1891L95
| | B. stricta (Schrad.) Robins. 1909 (see below for synonymy)L95
| `--B. subg. Chaetodiscus sect. Naiadothrix (Pennell) Pennell 1946 (see below for synonymy)SP56
| |--B. reflexa [=Herpestis reflexa]SP56
| `--‘*Benjaminia’ utriculariiformis Martius ex Benjamin 1847SP56
`--+--Gratiola Linnaeus 1753OP01, A61
| |--G. aureaC55
| |--G. ebracteataH93
| |--G. heterosepalaH93
| |--G. nana Benth. in DC. 1846 [incl. G. concinna Colenso 1887]A61
| |--G. neglectaH93
| |--G. officinalisC55
| |--G. pedunculataBR65
| |--G. peruviana [incl. G. latifolia]C06
| |--G. pilosaOP01
| `--G. sexdentata Cunn. 1838 [incl. G. glandulifera Colenso 1885]A61
`--LimoselleaeOP01
|--Amphianthus pusillusOP01
`--Limosella Linnaeus 1753A61
|--L. acaulisH93
|--L. africanaRHS09
|--L. aquaticaC06
|--L. ciliata Colenso 1889 (n. d.)A61
|--L. curdieana Muell. 1875A61
|--L. lineata Glück 1934BR65 [incl. L. aquatica var. tenuifolia Hoffm. 1804A61]
| |--L. l. var. lineataA61
| `--L. l. var. spathulata Glück 1934A61
|--L. subulataH93
`--L. tenuifolia Nutt. 1818 non L. aquatica var. tenuifolia Hoffm. 1804A61 [incl. L. australisC06]
Bacopa innominata (Maza) Alain 1956 [=Conobea innominata Maza 1894; incl. B. cyclophylla Fern. 1939, Herpestis rotundifolia Gaertn. f. 1807 non B. rotundifolia (Pursh) Wettst. 1891]L95
Bacopa monnieri (L.) Pennell 1946 [=Lysimachia monnieri L. 1756, Ba. monnieria (L.) Wettst. in E. & Pl. 1891, Bramia monnieri (L.) Drake 1892, Gratiola monnieri L. 1759, Herpestis monnieri (L.) HBK. 1818, Monniera monniera Britt. 1894; incl. M. calycina Kuntze 1891]L95
Bacopa repens (Sw.) Wettst. in Engl. & Prantl 1891 [=Gratiola repens Sw. 1788, Herpestis repens (Sw.) Schlecht. & Cham. 1830, Macuillamia repens (Sw.) Pennell 1923; incl. M. limosa Pennell 1920, Bacopa limosa (Penn.) Standl. 1928]L95
Bacopa stricta (Schrad.) Robins. 1909 [=Herpestis stricta Schrad. ex Link 1822, Caconapea stricta (Schrad.) Britton 1925, Monniera stricta (Schrad.) Ktze. 1891]L95
Bacopa subg. Chaetodiscus sect. Naiadothrix (Pennell) Pennell 1946 [=Naiadothrix Pennell 1920; incl. Benjaminia Martius ex Benjamin 1847 non Vell. 1835, Quinquelobus Benjamin 1847 (nom. inv.)]SP56
*Type species of generic name indicated
References
[A61] Allan, H. H. 1961. Flora of New Zealand vol. 1. Indigenous Tracheophyta: Psilopsida, Lycopsida, Filicopsida, Gymnospermae, Dicotyledones. R. E. Owen, Government Printer: Wellington (New Zealand).
[BR65] Black, J. M., & E. L. Robertson. 1965. Flora of South Australia. Part IV. Oleaceae–Compositae. W. L. Hawes, Government Printer: Adelaide.
[C55] Candolle, A. de. 1855. Géographie Botanique Raisonée: Ou exposition des faits principaux et des lois concernant la distribution géographique des plantes de l’époque actuelle vol. 1. Librairie de Victor Masson: Paris.
[C06] Cheeseman, T. F. 1906. Manual of the New Zealand Flora. John Mackay, Government Printer: Wellington.
[H93] Hickman, J. C. (ed.) 1993. The Jepson Manual: Higher Plants of California. University of California Press: Berkeley (California).
[L95] Liogier, H. A. 1995. Descriptive Flora of Puerto Rico and Adjacent Islands: Spermatophyta-Dicotyledoneae vol. 4. Melastomataceae to Lentibulariaceae. Editorial de la Universidad de Puerto Rico.
[LK14] Lyons, M. N., G. J. Keighery, L. A. Gibson & T. Handasyde. 2014. Flora and vegetation communities of selected islands off the Kimberley coast of Western Australia. Records of the Western Australian Museum Supplement 81: 205–244.
[OP01] Olmstead, R. G., C. W. dePamphilis, A. D. Wolfe, N. D. Young, W. J. Elisons & P. A. Reeves. 2001. Disintegration of the Scrophulariaceae. American Journal of Botany 88 (2): 348–361.
[RHS09] Roux, J. P., S. D. Hopper & R. J. Smith. 2009. Isoetes eludens (Isoetaceae), a new endemic species from the Kamiesberg, Northern Cape, South Africa. Kew Bulletin 64 (1): 123–128.
[SP56] Smith, L. B., & J. M. Pires. 1956. An evaluation of Benjaminia Martius ex Benjamin. Journal of the Washington Academy of Sciences 46 (3): 86.