Erythranthe grandis is a coastal perennial species closely related to
E. guttata. Prior to flowering and during winter months, it often has spreading prostrate growth habit many lateral branches (stolons). The peak of flowering is typically from May through August, which is later than nearby inland populations of
E. guttata. as it is completely inter-fertile with other inland annual and perennial populations. Molecular genetic analyses have revealed that populations for
E. grandis cluster as a distinct group from nearby inland populations of
E. guttata. E. grandis has evolved a higher level of salt tolerance than other related inland populations of
E. guttata. ==Range==