Flowering phenology, display size, and fruit set in an understory dioecious shrub, Aucuba japonica (Cornaceae)

Abstract

I investigated the effects of display size and flowering phenology on fruit set in Aucuba japonica, an understory dioecious shrub pollinated by opportunistic insects. Natural variations in display size, flowering phenology, and fruit set were monitored in 1997. A hand-pollination experiment was also conducted to check whether pollen limitation was a factor in fruit set in the field. Increases in floral display size did not affect fruit set; the proportion of flowers that set fruit was almost constant irrespective of the total number of flowers per inflorescence, the total number of inflorescences per plant, and the total number of flowers per plant. The hand-pollination experiment showed that fruit set was not pollen limited despite the low mating probability that resulted from the combination of dioecism and the species' dependence on opportunistic pollinators. This was due, in part, to the fact that female flowers did not have a predetermined period of receptivity, but instead remained receptive until they received pollen. In contrast, flowering phenology did affect fruit set. Fruit set was most abundant when male and female flowering was most abundant. This suggests there was some degree of pollen limitation during the part of the flowering season when male flowers were scarce.

The Floral Biology, Breeding System and Pollination Efficiency of Schima superba Gardn. et Champ. (Theaceae)

“…exceeded 27.86 mm. This species belongs to species with large flowers according to the technical standard of Abe [28], and this may attract pollinators to visit flowers and increase pollination opportunities. The natural flower life ranged from 4 to 5 days, which categorizes the plant as a longer …”

“…The natural flower life ranged from 4 to 5 days, which categorizes the plant as a longer flowering type [28]; this enhances the opportunity of floral visits and ensures the stability of pollen flow. Flowers of S. superba have abundant and well-exposed rewards that are potentially easily exploited by a wide array of flower visitors: nectar can be reached by both short and long mouthparts.…”

Floral Phenology and Sex Ratio of Piratebush (Buckleya distichophylla), a Rare Dioecious Shrub Endemic to the Southern Appalachian Mountains

“…To determine floral phenological synchrony between male and female individuals, methods were established from a review of the literature (Barrett and Helenurm 1981, Abe 2001, EspiritoSanto et al 2003, Dafni et al 2005, Matsuyama et al 2009, McMullen 2011. A sample of 23 staminate and 20 pistillate piratebush individuals were selected along the established permanent transects.…”

Flowering phenology of Catopsis compacta (Bromeliaceae), a dioecious epiphyte in an oak forest

“…It is theorized that reproductive success for male individuals is mainly limited by the number of pollen grains reaching stigmas, whereas female reproductive success is limited by the amount of resources available to invest in seeds and associated structures (Abe 2001, Forero-Montaña & Zimmerman 2010. As a result, it is expected that male individuals should exhibit earlier and longer flowering periods as well as more colorful flowers, compared to female individuals (ForeroMontaña & Zimmerman 2010).…”