GRIN. Taxonomical details, with common names, distribution, and synonyms.
Links for Oenothera macrocarpa
Dave's Garden PlantFiles - Profile page with horticultural basics, and member-contributed photos and comments. (zones 4a-8b) (4 photos)
Heritage Perennials - Profile with description and horticultural details. (zone 3 - 9) (1 photo)
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) (7 photos)
Rare Find Nursery - Catalog detail page with description and horticultural information. (zone 4-7) (2 photos)
Rob's Plants - Plant profile with basic horticultural information and often personal observations. Also seed germination records. (5 photos)
Rock Garden Plant Database - Encyclopedic entry with taxonomical, botanical, and horticultural details. (1 photo)
Oenothera macrocarpa subsp. fremontii
Links
Dave's Garden PlantFiles - Profile page with horticultural basics, and member-contributed photos and comments. (zones 4a-8b) (4 photos)
(4 photos)