Abstract Detail

Pollination Biology

Cameron-Inglis, Hazel [1], Harder, Lawrence David [2].

Floral display dynamics in Delphinium glaucum: architectural effect or response to changing resources?

The number of flowers that a plant displays simultaneously (floral display size) can influence pollinator behaviour and mating outcomes. However, display size is not an elemental inflorescence characteristic, but instead depends on how many flowers open per day (anthesis rate) and their longevity. Thus, small changes in anthesis rate or floral longevity can affect the temporal pattern and maximum size of the floral display within an inflorescence. A rapid build-up of floral display may promote initial attraction of foraging insects, but large floral displays can also lead to higher geitonogamy through increased within-plant visitation by individual pollinators. We observed systematic variation in the rate of floral anthesis in Delphinium glaucum (Ranunculaceae). Specifically, anthesis rate started at 4 or so flowers opening per day, and subsequently declined with increasing inflorescence age to about 1 flower opening per day. This pattern could exist for two reasons: 1) as a predetermined architectural effect fixed by flower position, which may reflect the adaptive pattern of floral advertisement, or 2) as a spatial or temporal response to resource depletion by developing fruits. Slowing anthesis rate during a plant’s flowering period may allow it to conserve or reallocate dwindling resources. To assess the effects of architectural effects and changing resource dynamics on anthesis rate, we manipulated resource availability within inflorescences by systematically removing flowers from D. glaucum inflorescences during a flowering season and tracking flower phenology. We assigned plants to either an unmanipulated treatment or a bud-removal treatment, for which we removed the bottom 8 flower buds before inflorescences elongated and any flowers had opened. The first eight flowers per inflorescence, displayed on bud-removal inflorescences, opened during a longer period than the first eight flowers on intact inflorescences, but during an equivalent period to flowers 9-16 on intact inflorescences. Thus, flower position, rather than inflorescence resource status, seems to govern anthesis rate and its controlling influence on floral display size.

1 - University of Calgary, Biological Sciences, 2500 University Drive NW, Calgary, AB, T2N1N4, Canada
2 - University Of Calgary, Department Of Biological Sciences, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada

Keywords:
anthesis
Floral display
plant architecture
resource allocation
flower position
phenology.

Presentation Type: Oral Paper:Papers for Topics
Session: 13
Location: Salon 6/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 2:00 PM
Number: 13003
Abstract ID:1158
Candidate for Awards:Cinq Mars Award