Oenothera fruticosa (sundrops)

Low-growing, quickly spreading, and cheerfully bright in bloom, Sundrops are good as a sunny ground cover, or for mixing into a low meadow. Each large yellow blossom only lasts a day, but the bloom season goes from May through July. Rarely higher than 12", Sundrops can handle full or partial sun, and a variety of soil conditions. Easy! And if you suddenly have too many, easy to pull up.