Androecial development and the problem of monophyly of Loasaceae

Abstract

Patterns of androecial diversity, especially developmental attributes, led some investigators to question the monophyly of Loasaceae. Polystaminate members of the family may possess either centripetal or centrifugal androecial development; however, these characterizations are shown to be too simple to explain the complex developmental patterns. Loasoideae with putatively centrifugal androecial development also have centripetally initiated stamens. Antesepalous regions among Loasoideae have stamens in positions that are similar to those of the earliest formed stamens of Mentzelia and are thus hypothesized to be homologous. Important transitional character states among the Klaprothieae show that complex patterns among some Loasoideae are not as divergent from those of Mentzelia as previously suggested. Haplostemony of Gronovioideae and diplostemony of Schismocarpus also show homologies with the developmental patterns present in Mentzelia and Eucnide.