Epimedium

Epimedium, also known as barrenwort, bishop's hat, fairy wings, horny goat weed, or yin yang huo (Chinese: 淫羊藿; pinyin: Yínyánghùo; Wade–Giles: Yin²-yang²-huo⁴), is a genus of flowering plants in the family Berberidaceae. The majority of the species are endemic to China, with smaller numbers elsewhere in Asia, and a few in the Mediterranean region. Epimedium species are deciduous or evergreen hardy perennials. The majority have four-parted "spider-like" flowers in spring. The species used as a dietary supplement is Epimedium grandiflorum. It contains icariin, which is a weak PDE5 inhibitor, in vitro. Its clinical effects are unknown. While there is little clinical evidence to date, as sildenafil, vardenafil, and tadalafil – sold under the brand names Viagra, Levitra and Cialis – are all based on (stronger) PDE5 inhibitory action, it is thought to have erectogenic properties and is found in some men's sexual health supplements....read more on Wikipedia.