Yellow Flowers Oenothera biennis Suncups Sundrops Seeds for Planting .It is the type genus of the family Onagraceae. Common names include evening primrose, suncups, and sundrops. They are not closely related to the true primroses (genus Primula). Oenothera laarckiana, or Evening Primrose, is a popular wild flower seed that looks lovely in a naturalized setting or growing along a fence line. This variety has large, 2 inch blooms of yellow that are sweetly scented and attract bees and butterflies. Evening primrose self-seeds, so it's possible that unless properly cared for, it could easily take over your garden. Still, its pretty, lemon-scented yellow flowers can lure many gardeners with their beauty. The plant's blooms open in the late afternoon and evening and close throughout the day, attracting a different set of nighttime.Evening primrose is one of the easiest plants you can grow in your garden. It prefers full sun but can grow in slight shade too.