The following CBHL member libraries have extensive LibGuides on various subjects.
Arboretum Library, Los Angeles County Arboretum & Botanic Garden
Lenhardt Library, Chicago Botanic Garden
McLean Library, Pennsylvania Horticultural Society
Michigan State University Library
Mt. Cuba Center Library and Archives
New York Botanical Garden Library
The New England Botanic Garden at Tower Hill
University of Hawai’i at Manoa Library