Goat weed has been used as an herbal medicine for two thousand years in China, where it is naturally prevalent. Legend has it that goat weed was discovered by a Chinese goat herder who noticed increased mating activity in his flock after they grazed upon a weed which was later identified as goat weed. Most strains of the weed are characterized by having four petals and flowers that look like spiders which bloom during the spring. Some strains have flowers appearing as upside-down crowns which garnered the plant its "bishop's hat" nickname. Some believed the weed to be responsible for barrenness in women, thus the nickname "barrenwort." However, the vast majority believe it to be an aphrodisiac, thus the nickname "horny goat weed."
A few varieties of goat weed have been cultivated in Europe and America since the mid- to late-1800s. The plant has proven an ability to propagate itself outside the boundaries of its native home in China and Japan. Multiple Chinese and Japanese strains are successfully cultivated in America today. The plant can be divided in late August, which allows its roots to regrow rapidly before the onset of winter.
All strains of goat weed thrive in moist, well-drained, humus-rich soil. They are forest-floor plants and do best in shade with some shelter for emerging leaves. A dry, sunny location quickly kills the plant off. When cared for, they grow rapidly, making them a good candidate for shady ground cover. Flowers appear in a wide range of colors. Leaves on some strains turn purple and crimson in the fall, while others are evergreen, even during the winter months.
Goat weed has been used as a garden plant, particularly for ground cover in Japan, for centuries. Goat weed is commonly used as an herbal supplement to treat decreased sexual drive. Its main ingredient, icariin, is believed to raise levels of nitric oxide, which has the result of relaxing smooth muscles, such as those that comprise sexual organs. Icariin may also have an effect on stimulating bone tissue growth, making it a possible positive treatment against preventing or reducing osteoporosis.