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/539802467nas a2200265   4500008004100000020001400041245014000055210006900195300001200264520162500276653001301901653003001914653001401944653001101958653002101969653001601990653001402006653003402020653001402054653002502068653001302093100002002106700002702126856004802153       2013                        eng d  a1095-833900aThe evolution of alternative mechanisms that promote outcrossing in Annonaceae, a self-compatible family of early-divergent angiosperms0 aevolution of alternative mechanisms that promote outcrossing in   an/a-n/a3 aAnnonaceae flowers are generally hermaphroditic and show high levels of outcrossing, but unlike many other early-divergent angiosperms lack a self-incompatibility mechanism. We reassess the diversity of mechanisms that have evolved to avoid self-pollination in the family. Protogyny occurs in all hermaphroditic flowers in the family, preventing autogamy but not geitonogamy. Herkogamy is rare in Annonaceae and is likely to be less effective as beetles move randomly around the flowers in search of food and/or mates. Geitonogamy is largely avoided in Annonaceae by combining protogyny with floral synchrony, manifested as either pistillate/staminate-phase synchrony (in which pistillate-phase and staminate-phase flowers do not co-occur on an individual) or heterodichogamy (in which two phenologically distinct and reproductively isolated morphs coexist in populations). Unisexual flowers have evolved independently in several lineages, mostly as andromonoecy (possibly androdioecy). Functionally monoecious populations have evolved from andromonoecious ancestors through the loss of staminate function in structurally hermaphroditic flowers. This has been achieved in different ways, including incomplete pollen/stamen development and delayed anther dehiscence. Angiosperms display an enormous diversity of mechanisms to promote xenogamy, many of which are easily overlooked without fieldwork. Floral phenology is particularly important, especially cryptic differences in timing of organ maturation or abscission. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 00, 000–000.10aautogamy10adelayed anther dehiscence10adichogamy10adioecy10afloral synchrony10ageitonogamy10aherkogamy10aincomplete pollen development10aprotogyny10aself-incompatibility10axenogamy1 aPang, Chun-Chiu1 aSaunders, Richard, M K  uhttps://annonaceae.myspecies.info/node/5397