Horticulture Supervisor, Kyle Cheesborough
First up is shrubby St. John’s wort, Hypericum prolificum, a shrub-like perennial reaching 3’ in height, with numerous branches, a woody base, and shredded bark. In summer, lemon-yellow blooms open to reveal pom-pom like anthers, covered in pollen. Bumble bees find shrubby St. John’s wort irresistible, and are the primary pollinators for this native plant. Somewhat drought-tolerant, shrubby St. John’s wort performs well in a range of garden soils and full sun. The botanical genus ‘Hypericum’ refers to a toxic chemical, hypericin, produced by the plant that can cause a rash on some animals and will upset the digestive system, making shrubby St. John’s wort undesirable to herbivores. The Gray Hairstreak butterfly uses Hypericum prolificum as its host plant, along with a number of moths.
Slender mountain mint, Pycnanthemum tenuifolium, another native perennial, blooms in the summer with hundreds of small, white-to-lavender flowers adorning the tops of the tall, 3-4’ herbaceous stems. Slender mountain mint is a vital summer nectar source for a number of native pollinators, including native bees, butterflies, wasps, beetles, and flies. Pycnanthemum tenuifolium has mint flavored foliage, and is often used in teas and as a substitute for the often aggressive mint plant. Slender mountain mint can be aggressive as well, slowly creeping outward, and requiring annual removal from areas where it is not welcome.
Finally, we have the butterfly bush, Buddleja davidii, a non-native, woody shrub that can reach 15’ high, if not pruned to control size. Beginning in June, 6” panicles of trumpet-shaped, lilac colored flowers emerge, and with regular removal of spent blooms, flowering will continue until frost. The common name refers to the buffet of nectar provided to butterflies, whose long proboscis can reach into the tubular flowers to reach the sweet reward inside. In harsh winters in Missouri, butterfly bush will die back to the ground, emerging again in the spring. More mild winters, the branches may only die back a little ways, but annual pruning of limbs back to the crown will control the size of the shrub. Gardeners beware – this plant can become invasive and weedy in warmer areas, self-seeding and becoming a difficult to remove, noxious weed.
compiled by Cara L. Crocker