Our native Mexican Primrose-willow (Ludwigia octovalvis) is widely distributed: so much so that it’s as likely to be found in Samoa or Singapore as in the southern U.S. Its flowers certainly recall other primrose species, while its slender leaves suggest the water-loving willows found along the banks of ponds and streams.
Primrose-willow begins flowering in June or early July and continues well into November: bearing buds, blooms, and seed capsules simultaneously. On October 31, new flowers were developing on a multitude of plants I found in wet areas of the Big Thicket, including the Watson Rare Plant Preserve.
Once the flower is pollinated, its petals, style, and stamens fall away, leaving the four triangular sepals shown in the upper right of the photo below. As the plant ages and seeds develop, both sepals and stems develop a pleasing reddish color that contrasts nicely with the pretty yellow flowers.
Several Luwigia species serve as larval hosts for the Banded Sphinx Moth (Eumorpha fasciatus) and the Primrose Flea Beetle(Altica litigata). A variety of butterflies visit the plant, including this Gulf Fritillary that paused for a photo session alongside Village Creek near Kountze, Texas.