ABSTRACT

Inversostyly is a newly recorded flower polymorphism that was recorded in only one species of Scrophulariaceae (Hemimeris racemosa). Some populations have the two floral morphs that are produced in different individuals and differ in relation to the vertical arrangement of style and stamen. Style-down flowers have the style turned down to the flower base and anthers turned to the upper portion of the flower, and style-up flowers exhibit the reverse. In other populations, all individuals are homostylous, that is, male and female whorls are arranged in the same level. Although the record of the classical inversostyly was observed in only one species, there are two more records of inversostyly that resulted from flower resupination, called dimorphic resupination. Species presenting inversostyly and dimorphic resupination tend to have zygomophic flowers and a more specialized pollination system. The reciprocal positioning of the reproductive whorls between floral morphs is considered as a morphological strategy that maximizes pollen exchange between individuals of opposite morphs in the population.