Abstract Detail



Anatomy and Morphology

Johnston, Dylan [1], Davis, Arthur [1].

Growth and nectar production dynamics of the bifurcated floral spur of Impatiens hybrida (Balsaminaceae).

Floral nectar spurs are narrow and hollow outgrowths of either the sepal or petal whorls that most often serve to hold pollinator-attracting nectar. Although nectar is the most common reward a flower will produce to attract pollinators, it is exceptional for nectar to be held in a spur. Floral spurs are normally oriented in such a way to ensure that when a pollinator withdraws nectar from the spur, it’s body will contact the stigma, anthers, or both. These structures of varying length are hypothesized to have a strong influence in the evolution of floral diversity and plant-pollinator coadaptation and are considered key innovations. Floral nectar spurs are present in at least 21 families (19 dicot, 2 monocot) of angiosperms; in some families it is a universal feature, whereas in others only certain genera possess spurs. Even more interesting and less understood are subgroups of spur-producing species that generate multiple spurs, such as double or bifurcated spurs. Accordingly, growth and nectar production dynamics of the bifurcated floral nectar spur of Impatiens hybrida was followed throughout nine stages, based on bud size and morphological changes. Morphological and anatomical characteristics of the spur were investigated using light and scanning electron microscopy. Ultrastructural features of the spur, particularly the nectary within, were observed using transmission electron microscopy. The nectar of I. hybrida is produced by discrete nectaries within each bifurcated spur tip. These nectaries are characterized by dense nectary parenchyma and a smooth epidermal surface devoid of stomata or trichomes whereby nectar is suspected to pass through cuticular microchannels to enter the lumen of the spur. Patterns in nectar secretion were determined by nectar volume and solute concentration followed throughout flowering phenology in ten I. hybrida plants. Nectar volume and solute concentration initially increased, followed by an eventual decline until flower abscission. As the flowers were grown in a greenhouse lacking insects to consume nectar, any losses in nectar solute concentration are suggested to be due to nectar reabsorption. This research provides key insight into the growth and nectar production dynamics of rare and previously uninvestigated bifurcated nectar spurs.


1 - University Of Saskatchewan, Department Of Biology, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada

Keywords:
spur
nectar
development
Growth
Impatiens hybrida
Ericales
Balsaminaceae.

Presentation Type: Oral Paper
Number:
Abstract ID:742
Candidate for Awards:Cinq Mars Award


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