Maples have horticultural and economic significance, widespread distribution and diversity. The genus Acer has been estimated to contain 238 botanical taxa and naturally occurring hybrids. No single institution can cultivate a comprehensive collection of maples, due to climatic and physical space limitations. This multisite collection combines the climatic variation, expertise, leadership, and physical space of 12 institutions throughout the United States and Canada. Maples were only the second Plant Collections Network multisite collection and were recognized in January 2008.
Current combined holdings represent about 64% of the Acer taxa known to exist. The emphasis at each institution varies from botanical to horticultural. Some collections are of geographic focus, whereas others might support tree breeding. Yet all participating institutions are dedicated to germplasm preservation and see the benefits of working collaboratively.
Maples have posed challenges in seed and vegetative propagation; seed is best sown fresh and loses viability quickly, while grafted plants are not always vigorous or compatible with the rootstock. Conservation is a priority for several species, especially those in Asia and Central Europe where they are threatened by deforestation, poor regeneration, and climate change.
The invasive nature of other species deserves evaluation and rational action. In addition to attempting to address these issues, participants are building the collection to expand maple diversity, and are working together to elevate curatorial standards of ex situ maple collections. A Maple Curatorial Group made up of representatives from each participating institution is undertaking these tasks.