02322nas a2200169   4500008004100000245012200041210006900163260003000232300001100262490000600273520173400279100002002013700002402033700002002057700002702077856004802104       2013                        eng d00aFunctional Monoecy Due to Delayed Anther Dehiscence: A Novel Mechanism in <i>Pseuduvaria mulgraveana</i> (Annonaceae)0 aFunctional Monoecy Due to Delayed Anther Dehiscence A Novel Mech  bPublic Library of Science  ae599510 v83 a<p>Unlike most genera in the early-divergent angiosperm family Annonaceae, <italic>Pseuduvaria</italic> exhibits a diversity of floral sex expression. Most species are structurally andromonoecious (or possibly androdioecious), although the hermaphroditic flowers have been inferred to be functionally pistillate, with sterile staminodes. <italic>Pseuduvaria</italic> presents an ideal model for investigating the evolution of floral sex in early-divergent angiosperms, although detailed empirical studies are currently lacking. The phenology and pollination ecology of the Australian endemic species <italic>Pseuduvaria mulgraveana</italic> are studied in detail, including evaluations of floral scent chemistry, pollen viability, and floral visitors. Results showed that the flowers are pollinated by small diurnal nitidulid beetles and are protogynous. Pollen from both hermaphroditic and staminate flowers are shown to be equally viable. The structurally hermaphroditic flowers are nevertheless functionally pistillate as anther dehiscence is delayed until after petal abscission and hence after the departure of pollinators. This mechanism to achieve functional unisexuality of flowers has not previously been reported in angiosperms. It is known that protogyny is widespread amongst early-divergent angiosperms, including the Annonaceae, and is effective in preventing autogamy. Delayed anther dehiscence represents a further elaboration of this, and is effective in preventing geitonogamy since very few sexually mature flowers occur simultaneously in an individual. We highlight the necessity for field-based empirical interpretations of functional floral sex expression prior to evaluations of evolutionary processes.</p>1 aPang, Chun-Chiu1 aScharaschkin, Tanya1 aSu, Yvonne, C F1 aSaunders, Richard, M K  uhttps://annonaceae.myspecies.info/node/5398