12. Mecardonia
Ruiz & Pav.
Ten species,
North America, South America, Caribbean Islands.
Steyermark
(1963) and many earlier authors treated Mecardonia as part of the genus Bacopa.
Pennell (1946) provided a lucid discussion of the problems associated with
generic limits in the group and concluded that Mecardonia was not, in
fact, very closely related to Bacopa. The two genera differ in a suite
of floral characters, as well as in the kinds of secondary compounds produced.