Is there a plant that is a good source of testosterone?

For Matthew Alice:

Flax seed is supposed to be a good source of plant estrogen. Is there any such thing as plant testosterone? (Er...not that I need any extra, of course.)

-- Kennedy Gammage, Vista

Did Mark McGwire get where he is today on a diet of escarole and sunflower seeds? Uh-uh. Testosterone can be synthesized from a particular type of Mexican yam, but an all-yam diet won't do much except make you fat, sick, and yellow. Most of the research has gone into phytoestrogens for menopausal women, so maybe there's a chance that dogbane or buttercups will pump you up and we just don't know it yet.