Swamp St John's Wort

Wildlife Value

The clusters of yellow flowers are primarily bee pollinated. The foliage is mildly toxic to mammalian herbivores, so it is a great deer-resistant option. Leaf sap can also cause skin irritation when exposed to sunlight. Beetles and Syrphid flies may also visit the flowers, but they are less effective pollinators. The reward of these insects is the abundant pollen, as the flowers produce no nectar. The caterpillars of the butterfly Strymon melinus (Gray Hairstreak) reportedly eat the seed capsules, while the caterpillars of the moth Nedra ramosula (Gray Half-Spot) feed on the foliage.