Arnold Arboretum of Harvard University

Stewartia Collection

Arnold Arboretum of Harvard University
Boston, Massachusetts
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Robert E. Cook, Director
Kyle Port, Manager of Plant Records
Peter Del Tredici, Senior Research Scientist

Primary Focus:
Conservation-based collection focused on genetic diversity

11 taxa, 7 species

The Stewartia Collection began in 1918 when Ernest Henry Wilson collected Stewartia pseudocamellia from Korea. With species native to eastern North America, Japan, Korea, and China, Stewartia continues to be one of the Arboretum's taxonomic and horticultural target genera. With their white or pink camellia-like blooms in mid tolate summer, clean foliage taking on vibrant orange-red-to-purple tones in autumn, and striking mottled bark, Stewartias offer year-round ornamental interest. Growers found Stewartia difficult to propagate until plant propagators at the Arboretum developed a successful regime, making several species and cultivars now widely available. Researchers continue to develop and refine these propagation protocols. The Arboretum plans to expand its genetic diversity of S. pseudocamellia, and has recently acquired S. rostrata and S. sinensis, both of which are infrequently found in cultivation. A new hybrid, Stewartia x 'Scarlet Sentinel' originated spontaneously at the Arboretum. Most of the Stewartia Collection grows along the Chinese Path, where the Arboretum plans to expand interpretation of its focus on disjunct genera of eastern Asia and the eastern North America. Stephen Spongberg, the Arnold's former horticultural taxonomist who later became the director of the Polly Hill Arboretum, published the monograph of the genus. Polly Hill herself collected and propagated seed from trees at the Arnold Arboretum. The collaboration between these two institutions continues as the Arnold's collection complements the NAPCC Stewartia Collection held by the Polly Hill Arboretum. The Arnold Arboretum also holds NAPCC collections of Acer, Carya, Fagus, Syringa, and Tsuga.


Taxonomic References and Authorities:
A Review of Deciduous-leaved Species of Stewartia (Theaceae). Spongberg, S.A. Journal of the Arnold Arboretum. 53:182-214.

Flora of China. (Http://

July 2006