Abstract Detail



Ericaceae: Systematics, Ecology and Evolution

Nilsen, Erik [1].

Leaf functional traits in the context of vascular constraints and their significance to freezing and water stress tolerance in Rhododendron.

Fundamental leaf traits are important to many levels of plant ecology in a global context. Yet much variation exists across those trait gradients particularly when considering plants within one functional group.  Rhododendron is a model system for understanding the significance of leaf trait variation within a functional group. This report will focus on evergreen shrubs of Rhododendron and their potential application to Ericaceae in general. I first outline vascular structure and variation among evergreen Rhododendron shrubs. Leaf functional traits of evergreen Rhododendron species are considered and related to the overall functional syndrome of Rhododendron within the context of vascular limitations. Thermonastic leaf movements occur in temperate evergreen Rhododendron. Thermonastic leaf curling (TLC) responds to water stress and reduces photodamage of light reaction systems during the winter.  Thermonastic leaf rolling (TLR) responds to leaf temperature and provides additional protection against over excitation of the photosystems during the winter.  Although the mechanism regulating TLC is well established, the mechanism for TLR is still obscure. Leaf epidermal appendages (trichomes) are abundant and diverse among Rhododendron species. These appendages function for water conservation due to their spatial interaction with stomata. Approximately one third of all species in Rhododendron are tropical and are found in one lineage, Vireya that diversified through Southeast Asia. All the tropical species in Vireya contain variable amounts of idioblasts, which are not found in any temperate groups of Rhododendron. Idioblasts can increase leaf capacitance for relatively thin (nonsucculent) leaves and may have their highest significance for epiphytic Rhododendron species. All the leaf traits considered in this review are successful within the context of vascular structure and function in Rhododendron. Understanding the significance of variation in multiple functional traits within one group can elucidate an overall functional syndrome that may define other similar groups within a family of plants such as the Ericaceae.


1 - Virginia Tech, Department Of Biology, 3002 Derring Hall, Blacksburg, VA, 24061, United States

Keywords:
functional traits
Thermonastic
Water relations
Idioblast
trichomes.

Presentation Type: Colloquium Presentations
Number:
Abstract ID:217
Candidate for Awards:None


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