Shrubby St. John's Wort
(Hypericum prolificum)

Above: Flowering Shrubby St. John's Wort close-up

Left: Shrubby St. John's Wort in ASMSA garden

Plant Characteristics

Plant Preference/Growing Conditions:

Shrubby St. John's Wort is best grown in full sun to partial shade and in well-drained, moist garden soils. They are tolerant to most types of soil, including slow-draining clay and sand, among other types. It prefers partial shade, but it can withstand the full sun environments. However, there is a higher chance of root rot and wilting in sunny areas.

Growth Habit/Description:

It is a small-sized deciduous shrub usually around 2-4’ in height and 3-6’ wide with lance-shaped leaves. The leaves are 2-3" long and typically dark green, although they turn a yellow-green color in the fall. In June-August, some bright yellow flowers with big bushy stamens bloom, but, in August, are then replaced by 1/3-1/2" long, cone-shaped seed capsules. It has a thick, dense, and woody branch system, which consists of brown lower stems and green upper stems.

Bloom Season:

Yellow flowers start to bloom in early summer, and they stay full and vibrant until mid-late August. That is when they are replaced by cone-shaped seed capsules, which stay around until the end of winter.

Fall and/or Winter Interest?

Yes. The seed capsules in the fall and winter can provide a stable source of food for birds. It also helps with visual interest throughout the fall and winter when many other plants are dying.

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Distribution

Habitat: Shrubby St John's Wort is common from the East of the US to as far west as Texas. They are commonly found in many different environments, including meadows, upland prairies, upland woods, etc.

Native to Arkansas? Yes

Native to Garland County? Yes

Endemic to Arkansas? No

Ecological Value

Host Plant for Caterpillars?

Yes. Shrubby St. John's Wort is a host plant for the Gray Hairstreak (Strymon Melinus).

Other Known Ecological Value?

Yes. The flowers on the Shrubby St. John's Wort don't produce nectar, but they are commonly visited by bumble bees, halictid bees, and Syrphid flies. They are also a host for a variety of moth species.

Other Interesting Facts

Origin of Name: "Prolificum" refers to the stamens of the flowers. They are so bushy that they can obscure the petals.

Related Plant Species: Hypericum Prolificum is one of around 400 species of Hypericum. With that many species, there is a species for all growing conditions and habitats. For example, one that is very closely related to the Shrubby St. John's wort is the Spotted St. John's Wort. It looks and acts very similar to the hypericum prolificum, but the most noticeable difference is the presence of spots on the plants.

Use For Food/Medicine:

This plant has been used before to make teas that are used to treat anxiety, depression, insomnia, etc.

References

St. John’s Wort – Learn How to Choose | Piedmont Master Gardeners. piedmontmastergardenersorg. [accessed 2023 Sep 9]. https://piedmontmastergardeners.org/article/st-johns-wort-learn-how-to-choose/#:~:text=This%20shrub%20is%20easily%20grown.

Hypericum prolificum. Jersey-Friendly Yards. [accessed 2023 Sep 9]. https://www.jerseyyards.org/plant/hypericum-prolificum/#:~:text=Wildlife%20Value%3A%20The%20flowers%20do.