A Journey Through the Hypericum Genus

The name “St. John’s Wort” conjures images of golden summer blooms and herbal remedies meant to lift the spirit. Yet, behind this familiar name lies the expansive Hypericum genus, encompassing over 500 species worldwide, each with its own story woven into the tapestry of human history, medicine, and horticulture.

From ancient rituals to modern pharmacology, Hypericum species have been revered for their healing properties, vibrant beauty, and resilience. This article embarks on a journey through the Hypericum genus, exploring its ethnobotanical roots, regional connections, diverse species, scientific research, medicinal applications, and the reasons to welcome these plants into our gardens. I extend my deepest gratitude to the many incredible plantswomen, horticulturists, botanists and gardeners who have contributed to the celebration of Hypericum -- and to the Mackintosh's, Bob McCartney, and George Mitchell who all played a crucial role in Woodlanders being one of the first nurseries to cultivate and offer many rare Hypericum species since our founding in 1979.

II. Ethnobotanical History of Hypericum

The genus Hypericum, encompassing over 500 species, has been intertwined with human culture and medicine for millennia. The name itself derives from the Greek words hyper (above) and eikon (image), referencing the ancient practice of hanging the plant above religious icons to ward off evil spirits [1].

In ancient Greece, Hypericum species were utilized for their medicinal properties, treating wounds, inflammation, and various ailments. The plant's association with St. John the Baptist, whose feast day falls near the summer solstice, led to its common name, "St. John's Wort," and its use in midsummer festivals to protect against evil [2].

Beyond Europe, Hypericum species have held significant roles in traditional medicine across various cultures. A comprehensive review highlights that in China, 30 out of 64 recorded Hypericum species have been used ethnomedicinally by 15 linguistic groups, including the Dai, Dong, Han, Miao, and Mongolian peoples. These species have been employed to treat a range of conditions such as wounds, irregular menstruation, dysentery, hepatitis, jaundice, mastitis, and bleeding disorders [3]. This extensive use underscores the genus's significant role in traditional Chinese medicine and highlights its potential for further pharmacological research.

III. Connection to the Southeastern United States

The southeastern United States is home to a rich diversity of native Hypericum species, each adapted to specific habitats and contributing to the region's ecological tapestry.

Take, for instance, Hypericum lissophloeus—the Smoothbark St. John’s Wort. Found only in a handful of counties in Florida, this species wears its rarity like a whisper, growing in sloughs and shallow waters beneath slash pines and pond cypress. Its bark, unusually smooth and gray, earns it the name, and its blooms—though as golden as any—are framed by an aura of disappearance, threatened by habitat loss and hydrological change. To grow it in a garden is not only to admire its grace, but to echo an act of preservation.

Then there is Hypericum reductum, a low evergreen native to the deep sands of the coastal plain. It grows with the defiance of something small but certain, spreading across poor soils where others fail. In its needle-like foliage and compact form, one sees a kind of quiet fortitude, a fitting plant for those who value resilience more than extravagance. In the landscape, it performs like a native groundcover, refusing to fuss, flowering in sun-bright yellow when the dog days press hardest.

Hypericum frondosum ‘Sunburst’, by contrast, stands with pride. A cultivar of a southeastern native, it is beloved in gardens for its profusion of lemon-bright blooms and foliage with a ghost of blue. It is both ornamental and authentic—decorative without becoming divorced from its lineage. ‘Sunburst’ is a fine choice for borders and foundation plantings, where it lends both brightness and structure through summer’s height.

Hypericum nudiflorum is spare and elegant, with flowering stems that seem to rise unclothed—hence its name. This species, found in bottomland forests and along streambanks, has the lithe quality of something wild and rarely touched, making it well suited for naturalistic plantings and woodland edges.

The willow-leaved Hypericum salicifolia introduces a softer texture, its linear foliage nodding to riparian life. It offers a visual counterpoint to the bolder forms, with a grace that feels almost herbaceous, though it is decidedly a woody perennial.

Standing tall among them is Hypericum stans, a species whose name (meaning “upright” or “standing”) describes its posture as much as its presence. Rare in cultivation, it offers an architectural uprightness that speaks well in meadow-style gardens.

The myrtle-leaved Hypericum myrtifolium grows in coastal swamps and savannas, where gopher tortoises dig and pitcher plants bloom. It has a form and foliage reminiscent of Mediterranean shrubs, yet it is rooted firmly in the American South—a lesson in how botanical appearances can deceive.

Then there is Hypericum edisonianum, another Florida endemic, tucked away in only a few imperiled wetlands. It is a botanical ghost of Edison’s own century, named in his honor, perhaps because it carries a kind of electricity in its rarity and bloom.

Farther north, Hypericum kalmianum is a compact species that thrives in the Great Lakes region but adapts well to garden use. It is a tidy plant, suitable for the small-scale gardener, and brings yellow light to northern landscapes where summer is short and winter long.

Hypericum prolificum lives up to its name with an abundance of blooms. Native across much of the eastern United States, it is perhaps the workhorse of the genus—resilient, drought-tolerant, and willing. One might pass it by, but that would be a mistake; in its abundance is a generosity suited to modern gardens seeking less maintenance and more meaning.

Even rarer still are Hypericum lloydii and Hypericum densiflorum—the latter named for its dense clusters of blooms that light up summer thickets like candelabra. Both are underappreciated players in the southeastern chorus, and both deserve a place in gardens designed not merely for show, but for story.

To grow Hypericum, then, is not just to plant a shrub. It is to curate a lineage of species born of wetlands and uplands, acid sands and alkaline stone. It is to recognize that there is poetry in botanical variation—that no two species bloom in quite the same manner, and that such diversity is not confusion, but richness.

In choosing among them, the gardener becomes something more than a decorator. They become a keeper of genetic memory, a steward of local history, and a partner in the ongoing performance of place.

Hypericum mapped across the US, via https://bonap.net/TDC/CGD#

IV. Of Tinctures and Trials: The Medicinal Wisdom and Modern Science of Hypericum

There are plants whose power is carried in rumor, and there are plants whose virtues are earned—tested by time, trial, and the collective experience of generations. Hypericum, in its many forms, belongs firmly to the latter category. It is a plant of medicine, not fashion—a long-trusted ally in the apothecaries of shepherds, monks, and scientists alike. What the hill-folk once steeped into teas and pressed into wounds, the laboratories of the modern world now extract, quantify, and chart in peer-reviewed journals.

And yet, despite all our measuring, the truth of Hypericum lies somewhere between the mortar and the microscope.

For centuries, Hypericum perforatum—the best known of the genus—was employed in European folk medicine for its ability to lift melancholy, heal sores, and ward off unseen devils. Culpeper wrote of it in 1652 as “a singular wound herb for hurts inward and outward,” linking its powers to the midsummer solstice and the fiery disposition of the sun itself. This notion—that the plant held light within its tissues—was more than metaphor. Its compounds, now known to us as hypericin and hyperforin, are photosensitive, and even today cause caution in those who consume them in large doses under intense sun.

In the last century, science caught up with what the monks of old already knew. Researchers isolated hypericin, first noted for its antiviral and antibacterial properties. But it is hyperforin—less flashy in color, yet more pharmacologically active—that proved to be the greater treasure. A lipophilic phytochemical, hyperforin acts upon the central nervous system by inhibiting the reuptake of several key neurotransmitters, including serotonin, dopamine, norepinephrine, and GABA—a mechanism akin to that of pharmaceutical antidepressants. Yet it does so gently, often with fewer side effects, in mild to moderate cases of depression (Butterweck & Schmidt, 2007).

A robust body of clinical research now affirms Hypericum perforatum's efficacy in treating depressive disorders. A 2017 meta-analysis published in Systematic Reviews evaluated 27 clinical trials and found the plant extract to be more effective than placebo and on par with standard antidepressants—with a superior safety profile (Ng et al., 2017). Its extracts have also shown promise in alleviating symptoms of anxiety, somatic disorders, and even seasonal affective disorder—ailments that would have been called “melancholies” or “spleens” in older texts, but which continue to haunt the human frame.

And what of the broader genus? As the 2022 review by Zheng et al. in Frontiers in Pharmacology reveals, the medicinal potential of Hypericum is far from limited to one species. In China alone, over thirty Hypericum species have been used by fifteen ethnolinguistic groups to treat ailments ranging from bruises and mastitis to jaundice and epistaxis (Zheng et al., 2022). Extracts of lesser-known species, such as Hypericum japonicum, have demonstrated hepatoprotective and antitumor effects, while Hypericum sampsonii has been studied for its cytotoxic properties against cancer cell lines (Zheng et al., 2022).

The modern pharmacopoeia continues to sift through these species, finding in each new compound—xanthones, flavonoids, phenolic acids—echoes of old wisdom. These molecules, like the plants themselves, seem to speak in dialects: one anti-inflammatory here, another neuroprotective there. Their synergy is not easily replicated in synthetic form, and therein lies the perennial challenge of translating the living plant into pill or capsule.

Of course, no medicine is without its shadow. Hypericum can interfere with a host of pharmaceutical drugs, from blood thinners to contraceptives, owing to its induction of cytochrome P450 enzymes. Here again, ancient wisdom warns us: even the gentlest herb must be known well before it is administered. As with all things sacred and potent, respect is the price of access.

But Hypericum is more than a chemical profile. It is a symbol of light held in leaf. It is what the herbalist in Appalachia steeped to soothe a mind worn thin. It is what the friar gathered at dawn to press into oil, the petals still damp with dew. It is what we find today in a capsule on a shelf, yes—but also, and more profoundly, in the garden, where it grows with golden calm.

So let us not forget the full story: that Hypericum is a plant of body and spirit, of folklore and pharmacy. It is a bridge between the old world and the new—between the garden and the clinic, the homestead and the peer-reviewed study. To grow it, or to brew it, or to study it in a lab, is to walk the same path in different boots.

In a time when wellness is sold more than earned, and when plants are often commodified more than cultivated, Hypericum stands as a reminder: that healing, like gardening, begins with reverence.

VII. Horticultural Value: Why Plant Hypericum in the Garden

In a world increasingly paved and plastic, the humble Hypericum offers a benediction of sunlight to the weary garden. Its golden blooms—small suns strung delicately along woody stems—carry the memory of meadows long gone, the kind once edged with picket fences and the scent of warm clover, where bees hummed their hymns uninterrupted. There is poetry in Hypericum, yes—but also purpose.

To plant Hypericum is to make a quiet declaration in favor of permanence, pollinators, and the native good. These shrubs and subshrubs, whether erect or sprawling, thrive in lean soils and sun, where others might wither for lack of pampering. The gardener who chooses Hypericum chooses self-reliance, for these are plants that ask little and give generously. Their drought tolerance is not bravado—it is heritage, evolved in pinelands, sandhills, and glades where water runs thin and the soil is honest.

One need only walk among the Southern species—H. frondosum, H. prolificum, or the rare H. edisonianum—to see how well they wear our landscape. Their leaves shift from sage to blue-green, their stems often tinged red in summer’s heat, and their flowers erupt like July fireworks, drawing in native bees and butterflies in an ancient pact of mutual benefit. Hypericum blooms not just for us, but for the wild—and it asks us to remember that gardens, at their best, are not exhibitions but sanctuaries.

In more cultivated corners, cultivars like H. frondosum ‘Sunburst’ shine with a boldness fit for the most formal border. But even here, they carry the rustic lineage of their wild cousins. In foundation beds, they hold structure; on slopes, they tame erosion. Their berries—if permitted to form—dot the season’s end with small globes of color, feeding birds and memory both.

Yet, as with all things of power, discernment is required. Not every Hypericum is a welcome guest in the garden. Some, introduced with good intentions, have overstayed their welcome, spreading beyond their bounds and unsettling the native order. Hypericum perforatum, the common St. John’s wort, brought from Europe for its medicinal virtues, has become a cautionary tale. Once covering over two million acres in California, it crowded out native species and proved toxic to livestock, leading to its classification as a noxious weed in several states .

Similarly, Hypericum grandifolium, native to Madeira and the Canary Islands, has found the Californian climate too hospitable. Escaping cultivation, it now invades coastal sage scrub and grasslands, forming dense stands that displace native flora .

Therefore, the gardener must choose wisely, favoring native or well-behaved species that harmonize with the local ecosystem. To tend Hypericum is to remember that gardening need not always chase the exotic or the rarest specimen. Sometimes, the finest expression of stewardship is found in what belongs. Let the lilies strut and the camellias preen; Hypericum is the faithful companion, the workhorse poet of the native border. A plant for everyman and mystic alike.

So plant it not for trend but for truth. Plant it for the bees, for the dry places, for the children yet to ask the names of things. Plant it because some plants speak softly but carry the weight of heritage in their sap and seed.

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References

1. Morris Arboretum. (n.d.). Plant Names Tell Their Stories: Hypericum spp. (St. John's Wort). Retrieved from https://www.morrisarboretum.org/blog/plant-names-tell-their-stories-hypericum-spp-st-johns-wort

2. McClung Museum. (2022, April 22). Saint John's Wort. Retrieved from https://mcclungmuseum.utk.edu/2022/04/22/saintjohnswort

3. Zhou, Y., He, X., Ma, W., Zhang, J., Zhou, T., Fan, G., ... & Wu, C. (2022). Hypericum genus as a natural source for biologically active compounds: A review. Frontiers in Pharmacology, 13, 957313. https://doi.org/10.3389/fphar.2022.957313

4. Butterweck, V. (2003). Mechanism of action of St John's wort in depression: what is known? CNS Drugs, 17(8), 539–562. https://doi.org/10.2165/00023210-200317080-00004

5. Mayo Clinic. (n.d.). St. John's Wort. Retrieved from https://www.mayoclinic.org/drugs-supplements-st-johns-wort/art-20362212

6. Linde, K., Berner, M. M., & Kriston, L. (2008). St John's wort for major depression. Cochrane Database of Systematic Reviews, 2008(4). https://doi.org/10.1002/14651858.CD000448.pub3

7. Butterweck, V., & Schmidt, M. (2007). St. John's wort: Role of active compounds for its mechanism of action and efficacy. Wiener Medizinische Wochenschrift, 157(13–14), 356–361. https://doi.org/10.1007/s10354-007-0424-0
8. Ng, Q. X., Venkatanarayanan, N., & Ho, C. Y. X. (2017). Clinical use of Hypericum perforatum (St. John's wort) in depression: A meta-analysis. Systematic Reviews, 6(1), 1–6. https://doi.org/10.1186/s13643-017-0763-4