The lemon-yellow flowers of evening primrose brighten up many harsh landscapes, as they happily sprout amid gravel and from cracks in pavement. Even more eye-catching is the cotton candy pink of the primrose moth (Schinia florida) seen in the center photo. Oenothera biennis is not only the larval host for this species, but also plays an important role in the life of the adult moth, which will visit the flowers for nectar and rest in them during the day. As the petals of the flower close, they wrap around the moth, keeping it concealed. To help it stay camouflaged, the outer edges of the moth’s wings poking out from the closed flower are the same pale yellow as the petals.
Uncovering the Beauty of a Roadside Wildflower
Among the many delights of gardening with ecology in mind is observing which beneficial native plants will pop up in landscape on their own. One of these is Oenothera biennis, or evening primrose, a biennial that is native across much of North America.
Commonly known as the source of evening primrose oil, a popular herbal remedy, it also has excellent ecological value. Oenothera biennis is a common "weed" along roadsides, especially in sandy or gravelly soil. It has a two-year life cycle, starting as a basal rosette in the first year, and then growing to be 4 to 8 feet tall in the second year. Each plant dies after going to seed, so evening primrose won't persist in a landscape unless its seeds are able to germinate, which they do most readily in recently disturbed or bare soil. While this species spreads too aggressively to be the right fit for every landscape, it works particularly well in meadow-style plantings, paired with other tall and robust wildflowers like New England aster (Aster novae-angliae), common vervain (Verbena hastata), or goldenrods (Solidago spp.)
Let the Oenothera biennis flourish for its pale yellow, lemon-herbal scented flowers, and especially for its value to insects and birds. It is a larval host to several moth species, including the primrose moth (Schinia florida). Its flowers open at dusk and at dawn, attracting both night-flying moths and bees active in the early morning. Each plant produces abundant buds along its vertical stem(s), which bloom gradually, allowing the plant to stay in flower from July through September. All of these buds generate copious oil and protein-rich seed, which is eaten by birds such as goldfinches in the fall. For all these reasons, it is listed as a top recommended plant for moth gardens in the New England region in the Xerces Society's book, Gardening for Butterflies. The next time it pops up in your landscape, give it a chance!