You can’t spend much time around South Florida natural areas without encountering species of St. Johnsworts, aka species of the genus Hypericum. The same is so around much of the world. You can’t spend much time around health food stores either without encountering Hypericum, and ditto for garden flowers. Hypericum is a jumbo genus multi-linked with human affairs. There are 400-500 species. About 8 are in Palm Beach County.
You can recognize Hypericums generically by their opposite leaves, tiny dots on the leaves, flowers with 4 or 5 yellow (in most species) petals, and central brushy tuft of usually more stamens than you can count.
Around here Hypericums inhabit habitats ranging from desert-like scrub to wetlands. The slashpine woods are dotted with poorly drained depressions that depending on circumstances can be lakes, seasonal ponds, marshes, puddles, or places to step into mud. Hypericums love those depressions.
You can visit a Hypericum pond now. CLICK to navigate John’s gigapan panorama taken last Friday. Pan around and zoom in. The fern in the middle is Swamp Fern, Blechnum serrulatum. The shrubby rim is mostly Hypericum fasciculatum, with additional SJWs hanging around too.
The chief marshy species is Peelbark St. Johnwort (Hypericum fasciculatum). This is that beautiful rounded, yellow-flowered, slightly woody shrub so characteristic of local marshes. Easy to recognize: look for showy peeling bark. You seldom see it cultivated, although this and other native Hypericum species are in native plant nurseries (www.afnn.org). Eye-pleasing non-native species, hybrids, and cultivars are garden flowers, groundcovers, and cut flowers around the horticultural world. Most decorate cooler zones than ours, but we’re not excluded. Gardenersin South Florida might start with Top Tropicals Nursery: When marketed cut, the pretty parts include the multicolored pods. CLICK for pretty pods.
My first awareness of Hypericum was in Michigan, where I remember conversation about “Klamath Weed” (H. perforatum) and others as a livestock poisons. Klamath Weed was introduced from Europe (followed by beetles as biocontrols), and we have plenty of our own species too. A symptom of livestock poisoning is skin sensitivity to sunlight.
That is why the labels in the health food stores warn users to shun the sun. The main medicinal use of St. Johnswort is to counter anxiety or depression. Does it work? I am extremely leery of herbal remedies, but let’s see what the University of Michigan Health System where they evaluate herbal products on-line says. For depression they assign a 2-star rating, which means, “contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.” There is some evidence of positive effect, and negatory evidence also, plus a warning that SJW is likely to interfere with other medications and possibly cause drug interactions. Note added Feb 2014: A health column in the Scripps Treasure Coast Newspapers Feb. 23 014 7E mentioned eye problems plausibly attributed to extended use of SJW to counter depression.
There is one 100% safe and effective way to apply Hypericum against depression: Go visit a Hypericum wetland on a sunny day, savor the sunshine, look for those yellow blossoms, and don’t worry.