Dave's Garden. Search the extensive PlantFiles database.
Links for Asperula tinctoria
Denver Botanic Gardens - Description, native range, and cultural requirements. (zone 4) (3 photos)
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) (2 photos)