St. John's Wort is native to much of Europe, northern Africa and western Asia. It has escaped cultivation and become established in many other parts of the world, especially Australia and the US. St John's Wort is a short-lived herbaceous or semi-woody perennial sub-shrub that grows in an open, bushy clump up to 2-3 ft (0.6-1.2 cm) tall and 2 ft (0.6 m) across. It spreads by runners and by profuse seeding. The stems have two raised ridges along them and are woody at their bases. Perforate St. John's wort has opposite leaves that are oval and a little over 1 in (2.5 cm) long. The leaves are scattered with translucent dots that, when viewed from the underside (a hand lens may be necessary), look like little round holes that go all the way through the leaf. These are oil-filled glands, and this is a characteristic common to nearly all of the hundreds of species of Hypericum. Perforate St. John's Wort blooms profusely throughout the summer and fall, producing clusters of bright yellow star-shaped flowers. The flowers, about 1 in (2.5 cm) across, have five black-dotted petals and many prominent yellow stamens which collectively look like fine bristles of a brush. The foliage has a peculiar, distinctive odor and a bitter taste. When crushed, the flower petals may exude a red-colored oil.
Hypericum perforatum Plant Profile - Floridata, http://www.floridata.com/Plants/Hypericaceae/Hypericum%20perforatum/913 (accessed January 23, 2017).