What the slowness of walking in nature can do for physical and mental health for those trapped in the electronic, sedentary world of computers and cars. The why and what of hiking to supplement the when and how. Available at most bookstores now.
Boost your health with a walk through the seasons of nature
Discover the many physical and mental benefits of unplugging from the digital world and taking a walk in nature! As affluent societies have become more urban, they have become more sedentary and anxious in equal measure. The frequently frenetic movement from home to car to office to sit at a computer screen at the beginning of the day, repeated in reverse order at its end, has wreaked havoc on our bodies and our brains.
The Compleat Ambler is a recipe to brave the newfound world of what’s out there waiting to be seen—a guide to what is interesting and what matters in nature: the flora, fauna, fungi, and geology of the great outdoors. Revisit what our ancient ancestors knew: that exploring the natural world reawakens the body’s own evolved strictures to reach and maintain a balance of mental, physical, and moral well-being. Trekking through the seasons—with the flowers of spring, the birds of summer, the fruits of fall, the rocks of winter—The Compleat Ambler eloquently illustrates why it’s so important that we “eat right, walk more, and seek trees.”
About the Author: William Needham holds degrees in science from MIT, engineering from Duke, education from Troy State, and business from Central Michigan—an eclectic educational background that reveals his wide-ranging interests. He has trained as a Master Naturalist in the state of Maryland and as an active hike leader with the Sierra Club, along with serving seven years as a docent at the Smithsonian American History Museum in Washington, D.C. After retiring as a captain in the U.S. Navy submarine service, William met his wife, Marina, while hiking on the Appalachian Trail in Pennsylvania. They currently live in Columbia, Maryland.
Common Name: Northern Walkingstick, Common American Walkingstick – Probably the most appropriately named of all invertebrates … for all intents and purposes, this insect looks like a stick that is, incongruously, walking on spindly legs. Even though it is named northern, its geographic range extends south to Florida and west to New Mexico.
Scientific Name: Diapheromera femorata – The generic name has no established etymology, but may imply that the use of chemical signals (pheromones) by these insects, “dia-” meaning consisting of. The species name is from femur, the Latin word for thigh and the name of the longest human leg bone. The plural form is femora so multiple femurs are implied.
Potpourri: Walkingsticks are not hiking poles although the two terms have been used synonymously with the former applied the latter but not vice versa. The walkingstick is a twig-like insect with legs to get from place to place, metaphorically like the poles that help the hiker do the same. Along with leaf insects that look like leaves, the walkingstick is one of the most compelling arguments for evolution according to Darwinian survival of the fittest. There can only be one reason why the complexities of a living, breathing, ambulating animal would be packed into an unlikely longitudinal and tubular package that looks like a stick except to fool a predator and thereby survive to procreate. Those that looked more like twigs over time became lunch less often, having off-spring that looked even more like twigs – and so on. Ultimately, the near perfect foil as indistinguishable from the perch on which it stands.
Historically, walkingsticks were placed in the order Orthoptera, which was an odd assortment of insects with a life cycle characterized by partial metamorphosis – egg, nymph, and adult with no pupation ― the nymph looks like a small adult. This taxonomy was impractical and unwieldy as it grouped cockroaches, mantids, grasshoppers, and crickets which have the straight wings for which the order was named (orthos is straight and ptera are wings in Greek) with the much more distinctive walkingsticks which are mostly wingless. Orthopteroid is still used as a descriptive unofficial category to refer to these insects with the addition of earwigs and termites, which, like mantids, are evolved from cockroaches.  The new stick insect order is Phasmatodea, from phasma, the Greek word for apparition or ghost. Insects that are almost invisible due to their extreme crypsis like the walkingsticks and the mostly Australasian leaf insects (there are none in the Americas) have long evoked a sense of the supernatural and were considered an anomalous category for which numerous names were variously applied, such as Cheleutoptera, Ambulatoria, and Spectra (from the Latin word for ghost).  Absent the theory of evolution, their presence would suggest that a twig or a leaf had suddenly come alive like the argumentative apple trees of Oz or the methodical ents of Middle Earth; a specter was the only available. explanation from the animist perspective. The taxonomy of the phasmids, as they are commonly called, is far from settled but the walkingstick insects are tentatively placed in several suborders and the walking leaf insects are for the present in the family Phylliidae. This will surely change.
Walkingsticks are an extreme case study of adaptations that must be made by all living things to survive in an ecological niche, humans excepted as makers of the dominant “niche” at the expense of other species. Life starts for the hatchling walkingstick as a nymph emergent on the forest floor in mid-June elongated in form like the walkingstick it will become, but diminutive in stature and bright green in color. Rather than a stick, it might be mistaken for any of the green larvae that course about the forests and are the provender for many a predator. The nymphs walk to the nearest thing they can find and climb to the leaf level under the cover of darkness to begin a life of eating and growing. That is if they get that far. If a cement post is first encountered as a tenuous refuge, it won’t be for long, as the now obvious green shape is on display for any passing birds, the nemeses of walkingsticks. Their only defense at this stage is sacrificial amputation. Since a predator is likely to grab the first thing that it can, this would likely be one of the six conveniently extended legs. Walkingstick nymph legs are detachable to allow the body with the remaining five legs to survive; the removed leg regenerates within a few days to restore full mobility. Of the approximate one thousand species of walkingstick, almost all are found in tropical climates, where foliage is dense and escape more probable … there are only ten species in North America. 
Walkingstick nymphs that are either more fortuitous or perhaps have a better sensor suite find there way up a tree and out on a branch that supports multitudes of leaves extended by petioles from twigs. While not all that selective, they prefer black cherry (Prunus serotina) or hazelnut (Corylus americana) trees, choosing oaks (Quercus spp) as an alternative. As obligate herbivores, nymphs settle on an individual leaf to strip the preferable cellulose-rich plant tissues leaving only the vascular vein plumbing as a matrix of thin piping in its wake, skeletonizing the leaf. Those that remain concealed and can continue eating will molt (technically called ecdysis), shedding their green skin for the brown colors of the twigs they traverse. The molting process is repeated four more times going through each phase at about a two week interval as transitional forms called instars. The maturation to adulthood takes a long time that varies according to temperature … cooler weather promotes the growth of the nymphs. The period varies with annual and geographic weather differences that have been measured by field testing to vary from 74.7 days in one year followed by 84.9 days in the next. The unit degree-day is used as a direct measure of the time at temperature requirement for an individual plant or animal. It provides a metric for phenology, the study of natural phenomena that progress according to climate. It is determined relative to a standard mean temperature, mostly 65ºF in the United States, and can be applied above or below that level for cooling or heating. The northern walkingstick nymph requires 1835 degree days to reach adulthood―roughly 120 days if the average temperature is 80ºF. Over time this results in broader distinctions in growth and reproduction. Northern walkingsticks that are really in the north (New England and southern Canada) have a biannual life cycle while southerly northern walkingsticks reproduce annually. 
At some point in (almost) every animal’s life, there comes a time (puberty in humans), when growth is complete and sex becomes the predominant concern. Species survival mandates procreation. For the most part, this involves the combination of genes from a male and a female to literally engender some variation that enhances survivability in a changing world. Male walkingsticks are generally smaller than the females and in some species they attach themselves and ride on the back of the female until a time of her choosing. The tail of the male is configured into a clasper to latch on to the abdomen of the female to assist in positioning (Cheleutoptera, one of the alternate order names, is derived from chele, the Greek word for claw) so that mating can proceed with the transfer of a spermatofore. Many phasmids have the ability to produce fertilized eggs absent the participation of the male, a not uncommon characteristic called parthenogenesis.  Self-fertilization has the advantage of guaranteed progeny for short term survival with the disadvantage of decreasing genetic diversity for long term survival.
The result of a tryst or non-tryst fertilization is between one hundred and one thousand eggs, dropped from the treetops to the duff below. Oviposition occurs one egg at a time beginning in late August and ending in October eventually covering the ground with as many as 400 eggs per square meter. The eggs of phasmids are rugged, coated with a layer of calcium oxalate, and sculpted and have the colors, shapes, and textures of various plant seeds … the eggs of the northern walkingstick look like the seeds of legumes. The hard outer shell protects the embryo through the winter to survive until spring when the nymph emerges. It probably evolved to prevent wasp predators from penetrating the eggs. The eggs also have a rounded protuberance called a capitulum at one end that is similar in appearance to an oily appendage on many plant seeds called an elaiosome. The unusual egg characteristics contribute to egg dispersal. Ants collect seeds with elaiosomes and take them back to their nests to remove the nutritive lipids and proteins, leaving the reproductive portion intact, contributing to plant propagation. Bloodroot, spring beauty and trilliums, among others, use ants to distribute their seeds in this way, a mutualistic arrangement called myrmecophily. Ants fooled by the capitulum of the walkingstick eggs are unwitting accomplices in moving them to a safe location for the winter. The hard-shelled eggs also protect against damage when passing through the digestive system of avian predators after having consumed gravid female walkingsticks. Excised eggs were fed to one of the known bird walkingstick predators and its fecal pellets collected three hours later. Twenty percent of the eggs were still viable and two were successfully hatched into nymphs.  The ability to hitch a ride on the backs of ants or in the belly of a bird may explain the wide geographic dispersal of northern walkingsticks, which typically spend their entire lives in the same tree.
One would think that evolution would surely have stopped with the “intelligent design” of an insect that looks like a stick with eggs that look like seeds. The contest between prey and predator is a continuum, however, as faster cheetahs foster even faster impalas. Birds are a highly evolved class of animals with about 200 million years of refinements largely to enhance their search for food, particularly high protein insects. Their keen eyesight can discern the slightest variation in a background pattern as impetus to take note and action. As the winds blow, the boughs move with graceful undulations that transmit through the interconnecting branches to the leaves and twigs. A walkingstick standing still on a moving twig is a sitting duck for a watchful drake. Crypsis, the ability of an animal to avoid detection, is widely employed by both predators and prey to stealthily creep to within striking distance for the former or blend into the background for the latter. In most cases this takes the form of colors and shapes, the tiger stripes that mimic tall sunlit grasses and chameleon lizards that change color to become incognito are well known examples. Most backgrounds don’t move so the companion behavior pattern of those seeking to hide is to freeze, as toads do instinctively when threatened. But twigs move, so most walkingsticks do too. Studies of walkingsticks swaying in concert with the amplitude and periodicity of the wind-generated movement of twigs on which they perch have concluded that they are synchronous.  When the grim reaper beckons, having rhythm matters. Some walkingsticks have taken this one step further, employing chemical weapons in the form of irritating sprays that deter not only birds, but also mammals and even other insects. 
The long, thread-like, jointed legs of the stick insect are ungainly, splayed out in all directions in support of the cumbersome cylindrical body like a tethered Macy’s parade balloon. They are not the strut-like simple appendages that they seem, as walking on uneven surfaces with different textures at odd angles is a gravitational challenge. Each leg is terminated in a two-part foot pad with a toe that is adhesive and a heel that is what may be called stick-slip, having adjustable adhesive qualities. The physics of mobility require each foot to stay where it is placed firmly yet yielding to removal without undue force when motion proceeds. To do this effectively is evidently an important feature of walkingstick behavior, as the heel pads incorporate three features to ensure it sticks when pressure is applied, but slips freely when needed. The surface is covered with rounded individual hairs that flatten like a squash ball when squashed, resulting in a larger surface areas. As the weight or pressure is increased a second. shorter group of hairs is engaged to broaden the base. At the most compressed and adherent state, the hairs bend over to add a third dimension to the contact surface. The net result is a lot of friction for minimal applied force that can be readily and rapidly applied and released so the walkingstick can walk.  The modes and methods of the stick insects is of interest to science as a possible mechanism to enhance footwear performance just as the overall carriage of the ambulating animal may be useful in designing all-terrain robots. 
By all accounts, the walkingstick measures up as a success in the forest survival struggle. It is well hidden in its camouflaged exoskeleton, it reproduces with large numbers of protectively coated eggs, it eats voraciously but not too exclusively, it grows fast, and it gets around. So why is there not a plague of walkingsticks on occasion like the biblical locusts? They are both orthopteran insects so they are closely related. The swarming behavior of locusts is technically called kentromorphism, brought about by environmental factors that promote density dependent behaviors. It is the gregariousness of species that overwhelms an ecosystem. Walkingsticks are mostly solitary and they can’t fly, so large scale tree or crop devastation has not been an historical problem. They only spread at the rate of an eighth of a mile a year, even taking ants and birds into account. However, on a more regional scale, there have been numerous occasions where serious environmental degradation has been experienced. One report from 1874 noted the denuding of 25 acres of white oak and hickory trees in Yates County, New York. The density of walkingsticks was such that “they cluster upon a limb or fence-rail so thickly that they pile up upon one another, and one cannot enter the wood where they are, without having numbers on his clothing”. The worst recorded outbreak was in Ogemaw County, Michigan in 1936, when 2500 acres of oak trees were “completely stripped by the middle of July.”  However, unless they gain the mobility of flight through some future mutation, walking sticks will remain interesting, if esoteric, insects.
Marshall, S. Insects, Their Natural History and Diversity, Firefly Books, Buffalo, New York, 2006, pp 58-64.
Dossey, A. et al. “Developmental and Geographical Variation in the Chemical Defense of the Walkingstick Insect Anisomorpha buprestoides“. Journal of Chemical Ecology. 10 April 2008 Volume 34 (5). pp 584–590.
Common Name: St. Johnswort, Common St. Johnswort, Klamath weed, Goatweed, Perforate St. Johnswort – Saint John refers to Saint John the Baptist. The predominant etymology is that the flower blooms on or about 24 June, the Feast Day of Saint John in Catholic hagiography. There are several other theories that are described in detail below. Wort is from wyrt, Old English for herb.
Scientific Name: Hypericum perforatum – The generic name is probably a combination of hypo meaning below and erice, the Latin word for heath to describe its rocky, shrubby preferred habitat. Alternative explanations have been suggested as discussed below. The leaves have small translucent dots that look like little holes – perforare is Latin for “to bore through.”
Potpourri: St. Johnswort is good and bad … but not ugly. Numerous anther bearing male stamens project from the base of the ovary like a shock of spiky blond hair in a unique display of floral beauty. It is good as one of the most renowned medicinal plants with a tradition of healing that dates to antiquity. It is bad in part for the same reason. Plants produce chemicals to protect themselves from herbaceous insects. The unintentional consumption of large quantities of that same chemical by plodding herbivores can be pernicious. St. Johnswort is also good as a garden cynosure and several cultivars are grown horticulturally for that purpose. But this is also bad, as they can escape into the wild where reproductive success can overwhelm the delicate balance of an ecosystem. Nature is gray as a balance between the opposites of black and white … what is good for some is relative to that which is bad for others.
The Feast Day of Saint John the Baptist was perhaps the third most important holy day (whence holiday) in the medieval Christian calendar with the birth of Jesus on 25 December second and his Easter Sunday resurrection first. It is celebrated on 24 June, which is six months prior to Christmas in accordance with Luke’s Gospel (1:36) wherein the angel Gabriel informed Mary on the night of her immaculate conception that “your kinswoman Elizabeth in her old age has also conceived a son; and this is the sixth month with her who was called barren.” Just as Christmas conveniently falls near the winter solstice to coincide with the folk festivals that preceded it, Saint John’s day is close to its summer solstice counterpart with Earth at the solar antipode. Both holidays took advantage of extant customs and social gatherings and repurposed them from pagan saturnalia to deistic ritual. Saint John’s festival was replete with local customs that varied according to the time and the tradition. Among the more ecumenical of midsummer celebrations was the gathering of flowers, St. Johnswort among them. It was in many cases it was hung over the door to ward off evil spirits giving rise to a dubious alternate explanation of the genus name Hypericum as Greek for above (hyper) the door (eikon). 
The naming of one flower among many for a day given to the celebration of John the Baptist seems unlikely. An alternative etiology is that St. Johnswort was one of the most notable medicinal herbs in the Levant in an age when violent, bloody rampage and rape were rife. The Crusades were the culmination of the spread of Christianity north from Rome and Constantinople to the various Germanic and Slavic tribes that succeeded Pax Romana. Led by the Franks, the crusaders set out with religious fervor stoked by Pope Urban II in 1095 to free Jerusalem from the perceived Moslem yoke, eventually establishing a presence in the eastern Mediterranean that lasted until the fall of Acre in 1291. The Knights Hospitaller or Knights of Hospital of St. John the Baptist were formed to succor the Christians in the Holy Land in 1120, becoming “one of the noblest charitable bodies in the Christian world.” They certainly used a common herb for the treatment of their charges, which, due to their success as healers and fame as protectors, became identified with them as St. Johnswort. After the fall of Acre, the Hospitallers eventually resettled to Malta where they became the Knights of Malta until they disbanded five centuries later in 1799.  The legacy of their symbolic healing was retained eponymously with the wort they used.
It is not then surprising that St. Johnswort was gathered to celebrate the midsummer holiday. This was not just because it happens to bloom at about that time in northern temperate climates but because it was always good to have a store on hand for medical exigency. John Gerard was one of the more notable herbalists of sixteenth century England as the superintendent of gardens of one of Queen Elizabeth I’s primary advisors. He is credited with establishing the first comprehensive survey of medicinal plants even though his work is mostly plagiarized from an earlier work by the Dutch botanist Rembert Dodoen.  Gerard’s prescription for St. Johnswort was to steep the leaves, flowers, and seeds in olive oil and strain them to produce an “oile of the colour of blood” that could then be used as a “most precious remedie for deep wounds … or any wound made with a venomed weapon … because I know that in the world there is not a better.”  The reputation of St. Johnswort was further enhanced by divine provenance with the invocation of the doctrine of signatures by the botanist William Coles. The “signatures” idea started in central Europe with the assertion that God had made “herbs for the use of men” with “particular signatures, whereby a man may read, even in legible characters, the use of them.” Therefore, since the leaves of St. Johnswort are perforated with holes “like the pores of a man’s skin,” it was a “sovereign remedy for any cut in the skin.” 
With the benefit of modern laboratory assay, it is now known that St. Johnswort is a chemical cornucopia. The flowers, buds, leaves, and roots collectively contain at least ten classes of biologically active compounds ranging from amino acids to xanthones including thirty separate constituents. While some of these are necessary for the operations necessary to be a plant like photosynthesis, some are the result of ecological factors with which the plant must have contended in the past up to and including the present. This adjunct group, known generally as secondary metabolites, consists of molecular combinations randomly produced in response to things like sucking insects and pervasive bacteria. The war of the worlds that determines survival sub rosa is what makes plants (and fungi) excellent sources for potential human medicinals, as we seek to repel the same invaders. When the epidermal shield is breached by accident or assault, the body is wide open for exploitation. The chemicals of St. Johnswort have proven to be effective in stemming the tide of infection. One recent study tested oil extracts of Hypericum perforatum in incision models finding that they “possess remarkable wound healing and anti-inflammatory activities supporting the folkloric assertion.” 
The use of St; Johnswort has long since been extended well past basic first aid for cuts and bruises to a panacea for anything that ails the body either physically, or, in a thoroughly modern twist, mentally. Brewed as one ot the many herbal tea concoctions either in whole or in part, it has been promoted as a treatment for bladder problems, intestinal worms, diarrhea, and dysentery, among others. While there have been no clinical trials to prove efficacy, it is not beyond reason that the complex chemistry of St. Johnswort could have some ameliorative affect at least for some … and then there is the placebo effect; it works because you think it will. The known biologically active compounds of St. Johnswort include choline, pectin, rutin, sitosterol, hyperforin, hypericin, and pseudohypericin. The latter two compounds are notable as having anti-retroviral properties that are a key attribute of AIDS medications.  However, it is in mental health applications, notably depression, that St. Johnswort has been subject to rigorous trial and assessment. The results are mixed.
Treatment for mental disorders is not an exact science. There are no objective guidelines based on independent physical parameters on which to base diagnosis and treatment … no blood samples and no lungs to listen to. The Diagnostic and Statistical Manual of Mental Disorders (DSM) has eighteen broad categories ranging from anxiety disorder to sexual dysfunction. Diagnosis relies on verbal feedback from a patient concerning subjective assessments of moods, aspirations, and other quality of life measures. Treatment is largely trial and error prescription with a mix of psychopharmaceutic drugs and dose rates until there is patient-reported improvement. Mixing St. Johnswort with other drugs is the main reason for controversy concerning its use. Many studies have been undertaken to determine that it works if taken as a singular medication for depression. For example, a metanalysis of 66 studies involving over fifteen thousand mental health patients found that “hypericum extracts were found to be significantly superior to placebo, with estimated odds ratios between 1.69 and 2.03.” Further, there were fewer adverse effects with St. Johnswort than with other tested drugs so that patients were able to stick to the medication program.  The National Institutes of Health (NIH) is the gold standard for the health efficacy of medications. While it does not rule out St. Johnswort as a treatment for depression, it is emphatically stated that “combining St. John’s wort and certain antidepressants can lead to a potentially life-threatening increase in your body’s levels of serotonin, a chemical produced by nerve cells.” 
St. Johnswort is not a single plant. It is a family formally named Hypericaceae that consists of eight genera and over four hundred species that extends geographically across both temperate and tropical regions. The characteristic features of its constituents are shrubby plants having clustered flowers with five separate petals and five separate sepals and numerous stamens that are mostly yellow to orange.  Common St. Johnswort earned its moniker by being the most expansive species in the family. It is more than common, however. According to the USDA, it is an official weed in seven states, listed with the caveat “Caution: This plant may become invasive.” While it only invades disturbed areas generally leaving established habitats intact, it forms dense colonies that will crowd out native species nearby.  H. perforatum is native to Europe and was either accidentally introduced to North America with packing materials or purposely transplanted as a medicinal herb or ornamental garden flower … it was first noted in Pennsylvania in 1793. One century later it had migrated to the western United States and by 1940 it had reached Canada. It has since become a serious invasive problem in Mexico, Argentina, Chile, South Africa, Reunion, Japan, Australia, New Zealand and Hawaii. 
Common St. Johnswort is a problem because it is an extraordinarily successful plant. Each individual shrub produces an average of 33,000 seeds in a single season and each seed remains viable for at least three years―about half are still potent after fifteen years. The many seeds are small and therefore light enough to be dispersed by wind for distances as far as thirty meters, germinating even in marginal soils in shady locations. Once established, seed growth is supplemented by vegetative growth as rhizomes extend outward from the parent plant to produce a copse that then predominates. The seeds are also sticky to adhere to the coats of any passing animals for further dissemination. Aside from invasive weediness, a second problem arises incident to consumption of Common St. Johnswort by grazing animals. One of the unintended consequences of its complex chemical cocktail is that it causes photosensitization. This self-descriptive term means that exposed areas become sensitive to the photons of the sun’s energy field, particularly those in the ultraviolet range. For animals including humans, light-colored areas absorb more energy and are damaged … something like severe sunburn. This can wreak havoc with white (but not black) sheep and any other animal with white patches like horses and cattle. 
The alternative name Klamath weed is a case in point. The Klamath River basin of California was an important livestock grazing area that had succumbed to a gradual infestation of Common St. Johnswort in the early twentieth century. Starting in 1922, Dr. Harry Smith of California’s Department of Food and Agriculture sought a biological control agent, identifying several beetles that might be compatible. However, local resistance to introduced phytophagous species in a dense agricultural area stymied trials―a common issue due to fears of potential damage to cash crop staples. However, by 1944 over two million acres of rangeland had been essentially rendered useless by the “Klamath weed” and land prices plummeted as ranchers were unable to raise cattle due to the debilitating effects of photosensitization. Three candidate beetles were approved for introduction from Australia where they had already been successfully deployed from their native Europe to control St. Johnswort. In spite of the acclimatization issues due to seasonal reversal, one of the three (Chrysolina quadrigemina) survived and thrived. Five thousand were released in 1946 to establish a population of three million by 1950 which were then distributed throughout the western states. After ten years, St. Johnswort had been reduced by over ninety percent as land values rose by a factor of four saving over three million dollars a year. 
St. Johnswort is one of the most notable examples of ethnobotany―the complex interplay between plants and people. Within the constraints of its indigenous fons et origio, it evolved chemicals to deter herbivores from its destruction and an industrial scale reproductive capacity to advance its quest for survival and dominance. Resourceful hunter gatherers learned of its potency through random trial and error, making it a key ingredient of the herbal healer’s medicine chest. It spread with the advances of civilization whose pioneers brought it with them wherever they went to treat the wounds incurred as rite of passage. Unchecked by local predators in these new places, St. Johnswort proliferated unabated. Reestablishing nature’s balance to control its epidemic proliferation mandated the importation of its native beetle predators to its new habitat. After centuries of relocation and decades of remediation, St. Johnswort is once again living in harmony with its environment. The only difference is that what once was used for physical wounds has been repurposed to treat the depressed mental wounds that seem quid pro quo to the frenetic pace of human endeavor. One can only wonder what John the Baptist might have thought of this.
https://www.cabi.org/isc/datasheet/28268 The Commonwealth Agricultural Bureau International is the primary agency for tracking invasive species and its impact on the food supply. This is a comprehensive fact sheet that also includes history, lore, and usage.
Durant, W. The Story of Civilization, Volume 4, The Age of Faith, Simon and Schuster, New York, 1950 pp. 585-613.
Gerard, John, Generall Historie of Plantes, John Norton Publisher, London, England, 1597, pp. 123-124.
Coles William, The Art of Simpling, Angell in Cornhill, England, 1656 p. 87 reprinted by Provoker Press, St. Catherines, Ontario, Canada, 1968
Greeson, J. et al. “St. John’s wort (Hypericum perforatum): a review of the current pharmacological, toxicological, and clinical literature”. Psychopharmacology 5 January 2001 Volume 153 (4): pp. 402–414.
Süntar, I. et al “Investigations on the in vivo wound healing potential of Hypericum perforatum L”. Journal of Ethnopharmacology 3 February 2010 Volume 127: pp. 468–77
Foster, S. and Duke, J. Medicinal Plants and Herbs, Houghton Mifflin Company, Boston, 2000, pp.128-129.
Linde K. et al (February 2015). “Efficacy and acceptability of pharmacological treatments for depressive disorders in primary care: systematic review and network meta-analysis”. Annals of Family Medicine. 13 January 2015 Volume 13 (1): pp. 69–79. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4291268/