Hypericum calycinum is a short, spreading shrub that bears bright-yellow flowers. This semi-evergreen plant is also called "Aaron's beard" and is part of a group of plants commonly called "St. Johnswort." This hardy plant does not suffer from serious diseases or insect pests and is an excellent choice for a groundcover on poor soil, according to the Missouri Botanical Garden.
Hypericum calycinum adapts to a range of growing conditions. For this reason, the plant has a far-reaching native habitat. H. calycinum is found growing in the wild from western Europe in Turkey to Bulgaria in Asia, according to Floridata.
H. calycinum grows best in temperate habitats with cool winters and mild summers. The plant thrives in U.S. Department of Agriculture (USDA) plant hardiness zones 4 through 8, according to Ohio State University. It grows best in cool, moist areas, and sometimes suffers during periods of drought.
The immediate habitat of H. calycinum can varies due to the plant's ability to adapt to many different types of soil conditions, including poor and sandy soils. Still, the plant grows best on well-draining, moderately fertile soil, according to Ohio State University. A habitat that provides full sun (in cooler climates) or morning sun followed by protective afternoon shade allows the plant to bloom to its full potential.
This strong, adaptable plant can be used in several different habitats, according to Ohio State University. H. calycinum prevents erosion and may be found growing on banks for that purpose, or along the foundations of homes and businesses. It competes well with tree roots for nutrients and is frequently used to fill in the space around deciduous trees.
Too much shade in H. calycinum's habitat will cause the plant to suffer from reduced blooming, according to the Missouri Botanical Garden. Hard freezes may kill the foliage to the ground, but in most cases, the plant will grow again when the weather warms up.