Missouri Botanical Garden - Plantfinder page for one of the plants growing at the garden, with usually one or more photos, horticultural information, and noteworthy characteristics. (zone 5-9) (15 photos). Also a page for 'Monstrosa'.
Rob's Plants - Plant profile with basic horticultural information and often personal observations. (7 photos)
Trees and Shrubs Online - Reference page curated by the International Dendrology Society with descriptive characteristics and horticultural notes. (15 photos)
Virginia Tech Dendrology - Factsheet with botanical characteristics and photos of various features. (zone 6-9) (6 photos)
(8 photos)