Heritage Perennials - Profile with description and horticultural details. (zone 2 - 9) (additional pages for other varieties)
Kemper Center - Plantfinder page for one of the plants growing at the Missouri Botanical Garden, with usually one or more photos, horticultural information, and noteworthy characteristics. (zone 3 to 7) (6 photos)
Paghat's Garden - Illustrated articles by a gardener in the Pacific Northwest, with background and personal observations. (4 photos). Also a page for 'Arendsii'.
Plant Delights Nursery - Catalog page with photo, horticultural basics, and descriptive blurb. (zone 5-8) (1 photo)
Rob's Plants - Plant profile with basic horticultural information and often personal observations. Also seed germination records. (3 photos)
(1 photo).