Names:  Barrenwort, Herba Epimedii, Horny Goat Weed, Japanese Epimedium, Xian Ling Pi, Yin Yang Huo. Epimedium acuminatum; Epimedium brevicornum; Epimedium grandiflorum; Epimedium koreanum; Epimedium pubescens; Epimedium sagittatum; Epimedium wushanese; and other Epimedium species.  

Family: Berberidaceae.

Properties:

tonify kidney yang – impotence, spermatorrhea, frequent urination, poor memory, painful and cold lower back and knees
expel wind-damp cold – spasms, cramps, joint pain, numbness
strengthen yin and yang, liver yang rising – dizziness, low back pain, irregular menses

Dosage:  6 – 15g.

Also Used For:

Orally, epimedium is used for impotence, involuntary ejaculation, weak back and knees, arthralgia, mental and physical fatigue, memory loss, hypertension, coronary heart disease, bronchitis, chronic hepatitis, polio, chronic leukopenia, viral myocarditis, and as a tonic and aphrodisiac.  

Epimedium is included in some personal care products for its antimicrobial effects.  

When large amounts are used orally - Some species can cause respiratory arrest

As many as 15 Epimedium species are interchangeable as "yin yang huo"