Hypericum gymnanthum

Common Names: Clasping-leaf St. John's-wort

Hypericum gymnanthum
Photo from Illinois Wildflowers Plant Database
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta - Flowering plants
Class:	Magnoliopsida - Dicots
Order:	Theales
Family:	Clusiaceae
Genus:	Hypericum
Species:	H. gymnanthum
Binomial name
Hypericum gymnanthum L
Natural range of Hypericum gymnanthum from USDA NRCS Plants Database.

Taxonomic Notes

Synonyms: none.

Varieties: none.

Description

H. gymnanthum is a perennial forb/herb of the Clusiaceae family that is native to North America. It reaches heights between 1 to 3 feet with cyme inflorescences containing 5 petals on each flower.

"Lower leaves much smaller than the medial and upper ones; medial and upper leaves firm, ovate-triangular, usually clasping, pointed apically, 5-7-nerved, about 1.5 cm long and 1 cm wide at the base, finely punctate-dotted, usually on both surfaces. Sepals 5, 3-5 mm long, lanceolate, long-acute to acuminate apically, oil tubes showing as lines. Petals 5, yellow, 3-6 mm long. Stamens few. Styles 3, 0.5-1 mm long. Capsules ellipsoid-conical, 3-4 mm long, equaling or slightly exceeding the calyx. Seeds buffish, minute, oblong, about 0.3 mm long, very faintly reticulate."

Distribution

H. gymnanthum is found throughout the eastern United States in several states: Florida, Georgia, South Carolina, North Carolina, Alabama, Mississippi, Louisiana, Texas, Arkansas, Tennessee, Virginia, Missouri, Kansas, Illinois, Indiana, Ohio, West Virginia, Pennsylvania, Maryland, New Jersey, and New York. It was added to the Kentucky flora in 2013, and is also disjunct in Guatemala, which might be an introduced population.

Ecology

Habitat

Common habitats include pine savannas, wet pine flatwoods, sinkhole ponds in Virginia, and other wet habitats. Wet habitats include bogs, muddy or sandy shores, swales, glades, and cypress depressions in flatwoods. Specimens have been collected from habitats including the edge of small ponds in longleaf pine woodland, wet roadside depression, moist loamy sands, the edge of wet savannas, and pine canopy forests. Within the southeastern coastal plain, H. gymnanthum is listed by the USDA Natural Resources Conservation Service as a facultative wetland species that most often can be found in wetland habitats but can also occasionally be found in non-wetland habitats.

Associated species include Phyla sp., Cyperus sp., Rhynchospora marliniana, Habenaria nivea, Aristida beyrichiana, Ilex glabra, Quercus elliottii, and others.

Phenology

Generally, H. gymnanthum flowers from June until September. It has been observed flowering in May, July, and August.

Pollination

While it usually reproduces asexually or through self-fertilization, it is thought to be possibly beetle-pollinated as well.

Conservation, cultivation, and restoration

H. gymnanthum is listed as endangered by the Maryland Department of Natural Resources, Natural Heritage Program and by the Ohio Department of Natural Resources, Division of Natural Areas and Preserves. It is also listed as extirpated by the Pennsylvania Department of Conservation and Natural Resources.