Hypericum sphaerocarpum is a species of flowering plant in the family Hypericaceae, commonly known as round‑fruit St John’s‑wort. It is native to parts of eastern and central North America.
Taxonomy
- Kingdom: Plantae
- Clade: Tracheophytes
- Clade: Angiosperms
- Clade: Eudicots
- Order: Malpighiales
- Family: Hypericaceae
- Genus: Hypericum
- Species: H. sphaerocarpum Nutt.
Description
Hypericum sphaerocarpum is a herbaceous perennial reaching 30–60 cm in height. The stems are erect and often branched near the base. Leaves are opposite, sessile, linear‑lanceolate, typically 1–3 cm long, and possess entire margins. The inflorescences are terminal cymes bearing 3–10 bright yellow flowers each. Flowers have five petals, each about 5–8 mm long, and numerous stamens arranged in several fascicles. The fruit is a characteristic spherical capsule, approximately 4–5 mm in diameter, containing numerous small seeds—hence the specific epithet “sphaerocarpum” (Greek for “round fruit”).
Distribution and Habitat
The species occurs in the United States from the Great Lakes region westward to the central plains, extending southward into parts of the Ohio Valley and the upper Mississippi Valley. It typically grows in open, calcareous habitats such as limestone glades, prairies, savannas, and rocky barrens, often preferring well‑drained soils with moderate moisture.
Ecology
Flowering occurs in late spring to midsummer. The yellow flowers attract a variety of pollinators, including bees and flies. The plant’s seeds are disseminated primarily by gravity and occasional water movement.
Conservation Status
Overall the species is not globally threatened; however, it is considered of conservation concern in several states where its specialized habitat—particularly calcareous glades—is declining due to land‑use change. It is listed as “S3” (vulnerable) or “S2” (imperiled) in certain regional conservation assessments.
References
- USDA, Natural Resources Conservation Service. “PLANTS Database: Hypericum sphaerocarpum.”
- Flora of North America Editorial Committee. “Hypericum sphaerocarpum.” Flora of North America (vol. 8).
- Gleason, H. A., & Cronquist, A. (1991). Manual of Vascular Plants of Northeastern United States and Adjacent Canada. New York Botanical Garden.
Note: All information presented is derived from established botanical references and reputable plant databases.