Few herbal supplements are better established or more widely
used than the one with that odd, funny name: St. John's wort.
(We'll get to the name in a minute.) Botanically, St. John's
wort is a yellow-flowering, rhizomatous, perennial herb
indigenous to Europe. It features woody, branched roots which
shoot runners in all directions; these runners produce stalks
growing as high as three feet. The plant blossoms in small,
bright yellow flowers about a quarter-inch across. The leaves
feature distinctive black dots -- often visible along the petal
margins -- which are actually glands containing hypericin, one
of the principal active constituents of St. John's wort. The
whole above-ground part of the plant is harvested when the plant
is just flowering, and both the flowers and leaves are used for
medicinal purposes. There are multiple species of St. John's
wort around the world, but the most frequently occurring species
is appropriately called common St. John's wort, and it refers to
the herb traditionally used fo