In the fall of 2015, Bartlett Tree Research Laboratories and Arboretum earned Plant Collections Network Accreditation for its Hamamelis Collection. Located in USDA Hardiness Zone 7, this collection represents a broad range of witch hazels well suited for home and urban landscapes. This represents the fifth Plant Collections Network recognized collection for Bartlett, with Acer and Ulmus collections also being accredited in 2015.