St. John's-worts are leafy herbs or shrubs, usually with
yellow or orange flowers in branched clusters.
The flowers are radially symmetrical with 5 separate sepals
and 5 separate petals. There are numerous stamens, usually
united into several clusters by the bases of the stalks. All
these parts are attached at the base of the ovary. The leaves are simple, opposite or whorled, with numerous,
often black or translucent dots.
The fruit is usually a capsule, sometimes a berry.
There are 8 genera and about 400 species, widely distributed
but most abundant in tropical and subtropical regions. Only 1 genus in our area.
Two compounds present in these plants (hypericin and pseudohypericin)
have been found to be potent anti-viral agents with no serious
side effects, so these plants are now being studied for use
in the treatment of AIDS.
Guide to Identify Presented Species of the
St. John's-wort Family
LEAVES BROAD, ALMOST
scouleri - Western St. Johnswort Stems 10-80 cm tall. Moist,
open slopes and ledges, foothills to alpine.
Flowers bright yellow, 2 cm wide, petals edged with small black
dots or teeth.
Leaves opposite, broadly egg-shaped, 1-3 cm long, black-dotted
Alphabetical listing with links to presented species of the St. John's-wort family: