Effect of flower number on the pollinator attractiveness and the threshold plant size for flowering in Pertya triloba (Asteraceae)

Abstract

Pertya triloba (Asteraceae) is a perennial herb growing in the understory of deciduous broad‐leaved forests in central Japan. Its capitulum consists of a single floret that differs from those of most other Asteraceae species. A bagging experiment clearly showed that breeding of P. triloba required cross‐pollination. By using female fertility as a measure of pollination success, the effect of an attractive floral display on the threshold plant size for flowering in P. triloba was surveyed. The number of florets per plant in a P. triloba population was artificially adjusted between one and 30. In both control plants and experimental plants with adjusted floret number, the seed set increased with an increase in the number of florets per plant and became constant (60%) when the floret number per plant was more than 10. Thus, the number of florets per plant has an important role in attracting pollinators, and more than 10 florets per plant must be the effective floral display size. In the P. triloba population, 98.5% of the flowering plants had 10 or more flowers. The effective floral display size might be determined through the mutual relationship between plants and pollinators. The number of florets per plant increased with an increase in the plant leaf area. Therefore, the threshold plant size for flowering might be determined by the productivity needed to support an attractive floral display.

Pollination Biology, Seed Dispersal, and Recruitment in Rudbeckia auriculata (Perdue) Kral, a Rare Southeastern Endemic

“…In addition, some types of pollinators exhibit density-dependent foraging behavior and may bypass small populations (Lamont et al 1993). Several studies have demonstrated that an increased floral display increases the number of pollinator visits (Klinkhamer et al 1989, Conner and Rush 1996, Kawarasaki and Hori 1999. This seems to be the case in this study, as we found a significant positive correlation between CPUE and the number of flowering stems.…”

“…during a study of that species in Utah. Many other species of Asteraceae have also been demonstrated to be self-incompatible or only partially self-compatible (Andersson 1991, Buchele et al 1992, Byers 1995, Leuszler et al 1996, Messmore and Knox 1997, Olsen 1997, Giblin and Hamilton 1999, Kawarasaki and Hori 1999, Costin et al 2001). This fact alone, however, does not explain R. auriculata's restricted distribution.…”

Ecological factors affecting the fruiting success of a Tibouchina trichopoda (DC.) Baill. (Melastomataceae) flower

“…In general, plants located in areas with abundant fl oral resources are more frequently visited and have superior fruiting success (Feinsinger et al 1991;Th ompson 2001, Klinkhamer & van der Lugt 2004. Populations with high fl oral density would be easily perceived by their pollinators (Kawarasaki & Hori 1999), especially those that focus their activity on populations where a large amount of resources are available, in order to minimize energy expenditure (MacArthur & Pianka 1966). Th is would allow pollinators to optimize their trade-off between the costs and benefi ts of their fl ights to gather resources (Klinkhamer & van der Lugt 2004).…”

Effect of Density and Flower Size on the Reproductive Success of Nothoscordum Graminum (Alliaceae)

“…Populations with high density of flowers would be easily perceived by pollinators (Kawarasaki & Hori 1999), with those concentrating their forage activity in these populations where a great amount of resources can be found. This will allow pollinators to optimize their trade-off between cost of flight and benefit by ingestion of resources (Jennersten 1988;Klinkhamer & Van der Lugt 2004).…”