PS 87-58
Secrets of rhododendron roots

Friday, August 14, 2015
Exhibit Hall, Baltimore Convention Center
Jaynell D. Nicholson, Biology, Kent State University Student, Kent, OH
Juliana Mederios, The Holden Arboretum
Oscar J. Valverde, Department of Biological Sciences, Kent State University, Kent, OH
Jean H. Burns, Department of Biology, Case Western Reserve University, Cleveland, OH

The Rhododendron genus can be found in many different habitats around the world but scarce in desserts, and dry forests as well as tundra regions. . Rhododendrons are studied from the xylem to the leaves: we believe roots are the key since there is little know about them. Kong et al., found two different dimensions of root trait diameter across 96 subtropical woody species: a diameter related dimension that may integrate root construction, and possibly maintenance and persistence, with a branching density dimension that may express difference in root plastic responses to environment. We addressed the question of what goes on in the roots and if the anatomy and morphology of the roots are connected to the temperature tolerance of different rhododendron species. The study site was the Helen S. Layer Rhododendron garden at the Holden Arboretum. We studied six species of Rhododendron from three sections: Ponticum (Maximum, Degronianum), Pentanthera (Austrinum, Molle), and Tsutsuti (Yedoense, Indicum). After selection/clipping parts of the roots, we scanned and analyzed them with Winrhizo that measured the diameter, specific root length, surface area, length of individual links, and specific root tip area when the mass of each individual sample is added.


After running our data through R for statistical analysis, we found that the Habit (Evergreen, Deciduous, or Dimorphic) and the minimum temperature a species can survive is affected by the average diameter of the roots (how thick they were), average standard root tip area (# tips per gram), and the average length per volume (length by volume) with all P Values<.05. We can conclude that the habit of Rhododendrons and the minimum temperature they can survive in are correlated. We also conclude that the morphology of their roots affects their habit and temperature survival. This research contributes to ecology by giving an understanding as to how the roots of plants evolved and what affects the environment has on the characteristics of roots.   Through further research, we can better understand what really goes on in Rhododendron roots and other woody plant species.