Issue:
116
Page: 50-71
Forest Gems: Exploring Medicinal Trees in American Forests
by Steven Foster
HerbalGram.
2017; American Botanical Council
Click here for PDF of this article.
Introduction
When Odysseus returned from Troy after a 20-year absence, he
found his aging father planting trees around his home. Odysseus asked, “Why,
being now so far advanced in years, would you put yourself to the fatigue and
labor of planting that which you are never likely to enjoy the fruits?” The old
man, taking him for a stranger, replied, “I plant trees for the benefit of my
son.”
The benefits of many trees outlast the human lifespan. Trees
have always played an important role in human affairs, one so intimate that
these arborescent living giants are often taken for granted and neglected: they
are just there. Trees have provided humans with shade, shelter, materials for a
vast array of objects, fuel, food, medicine, and oxygen. They also provide a
gift for future generations. Their uses are almost endless.
This article is not born of the expertise of the forester or
the taxonomic skills of the botanist; rather it is born of the curiosity of the
herbalist. When botanists speak of herbs, they refer to herbaceous plants,
those species without a persistent woody stem that die back to the ground each
year. The botanist’s tree or shrub has a woody stem or trunk. When an herbalist
speaks of an “herb,” he or she means any plant with fragrant, culinary, and/or
medicinal qualities. This article deals with both the botanist’s trees and the
herbalist’s herbs, which take their form as trees.
Humans came out of the forest in transit from hunter and
gatherer to cultivator of plants. Once-heavily forested regions have been
denuded of trees to make way for the cultivation of herbaceous plants as food.
Though humans plant trees in rows for fruits, nuts, and
timber, the attitude of clearing a forest to make way for other agricultural
pursuits persists in the human mind. Rather than viewing trees as temples of
life, humans tend to look at them in terms of board feet for timber, cords for
fuel, or as simple nuisances that prevent the soil from being pierced with a
plow. This is particularly acute in tropical rain forests today. How often has
this cycle been repeated in human history? How many great civilizations have
bitten the dust because of arrogance?
Having inhabited the earth long before humans, trees deserve
respect. Forests are often looked upon as mines. While developed countries
import large quantities of exotic hardwoods, which despoils tropical rain
forests, humans also clear cut American hardwoods, bulldoze them into piles,
then plant pines in their place. Perhaps woodworkers should plant a North
American hardwood for each piece of furniture produced.
Can humans afford to continue a way of thinking born of the
18th-century mind: that our fields and forest are unlimited resources? The answer
is obvious. Take a stroll among the trees. Foray among the myriad human uses
for trees in these personality profiles* of six trees from the eastern
deciduous forest. May it help to create a greater appreciation and respect for
trees as medicinal (and otherwise useful) herbs.
Black Walnut — Juglans nigra
From the stocks of Revolutionary War muskets to the rich
veneer of the finest Victorian furniture, the American black walnut (Juglans
nigra, Juglandaceae) has been the most venerated of American hardwoods since
European settlers first set foot on North American shores. The wood was
exported to England as early as 1610, with live fruits introduced by 1656. John
Parkinson described the species in his herbal Theatrum Botanicum in 1640. When
colonists first started harvesting the tree, it was abundant, but today, it is
more scarce through much of its natural range than it once was.1
The black walnut grows in rich bottomlands and fertile
hillsides from western Massachusetts and southern Ontario to South Dakota,
Illinois, Indiana, Arkansas, and Texas, eastward to western Florida. It is now
most abundant in the Ohio and Mississippi valleys and on the western slopes of
the Appalachians.
The native black walnut is one of the most important
economic trees in the eastern deciduous forest as a source of both cultivated
and wild nuts, dyes, wood materials, and biologically active compounds. In
fact, it is the most important tree to the Ozark economy. Each year, the
beginning of October marks the start of the buying season for wild black
walnuts in the Midwest, where more than 200 buying and hulling stations spread
across 11 states purchase upwards of 30 million pounds (more than 13.6 million
kilograms) of whole walnuts. The vast majority are purchased by the Hammons Products
Company in Stockton, Missouri, the world’s largest processor and supplier of
American black walnuts. The 2017 buying season began on October 2, with an
opening price of $15 per 100 pounds after hulling.2
Hullers remove the green outer pericarp of the fruit. If
picking up whole walnut fruits, one should be aware that the green husks can
cause contact dermatitis, and that the husks’ juglone content — a natural
allelopathic naphthoquinone that thwarts competing plant species beneath a
walnut tree — will stain clothing and skin orange-brown to black. Juglone and
extracts of walnut hulls have potential as broad-spectrum biocides or
bio-herbicides.3
The green outer husk itself is commonly discarded by
commercial walnut hullers, but an unknown percentage of the dried pericarp is
sold in the botanical trade. The use of the American species seems to have
mirrored that of the English walnut (J. regia). Traditional uses of black
walnut for treating intestinal parasites, for example, stem from the historical
use of English walnut for similar purposes. As noted by R.E. Griffith (1847),
“The rind of the unripe fruit is said to remove ringworm and tetter [eczema];
and a decoction has been given as a vermifuge with some success.”4 Culbreth
(1906) reiterated similar uses.5 Ethnobotanist James A. Duke, PhD, (1989)
recognized the continuation of this traditional use. Black walnut was never
official in the United States Pharmacopeia (USP).6
The husk contains potentially useful phenolic compounds with
antimicrobial and antioxidant activity. In 2016, Wenzel et al. developed a
supercritical fluid carbon dioxide extraction method with an ethanol modifier
that unlocked the potential to concentrate antioxidants from walnut husks.7
The hard inner shell encasing the walnut kernel or meat is
not discarded, but is valuable as an industrial abrasive. It is sold in a
variety of grades and six standard particle sizes as a soft, reusable abrasive
for blast-cleaning and polishing soft metals, fiberglass, plastics, wood, and
stone. As a tumble polish, it is used for jewelry, ink pens, and surface
preparation for painting, among other purposes. In the oil industry, it is used
to make and maintain seals. For water filtration, black walnut hull particles
are used in the separation of small-particle solid contaminants suspended in
water.8
Within the green outer layers lies the inner pericarp, or
the hard shell surrounding what humans and squirrels eventually hope to reach:
the kernel or walnut itself. Native groups throughout the tree’s range prized
the kernels as food, and they were eaten plain, sweetened with honey, and
cooked in soups.9 James Mooney (1932) wrote that it was taboo for pregnant
women to eat walnuts for fear that the child’s nose would be overly broad.10
Nutrient-dense black walnuts are high in lipids, protein, fiber, vitamins, and
minerals, as well as phenolic compounds and phytosterols. They are a rich
source of fatty acids including oleic acid, omega-6 linoleic acid, and omega-3
alpha-linolenic acid, among others.11
In 1837, the Legislature of Massachusetts initiated a study
of the woody plants of the state by George B. Emerson, a distinguished Boston
schoolmaster. This culminated in the publication of A Report of the Trees and
Shrubs Growing Naturally in Massachusetts (1846), which appeared in four more
editions by 1906. In summarizing the value of the walnut, Emerson wrote: “It
thus unites almost all the qualities desirable in a tree … beauty,
gracefulness, and richness of foliage, in every period of its growth; bark and
husks which may be employed in an important art; fruit valuable as food; wood
unsurpassed in durability for use, or in elegance of ornament.”12
Dogwood — Cornus florida
No tree in the eastern deciduous forest heralds spring’s
arrival with greater surety than the flowering dogwood (Cornus florida,
Cornaceae). In a range extending from Maine to Florida and west to Minnesota
and Texas, native groups marked the beginning of the anticipated renascent
season with the blooming dogwood. For indigenous peoples and European settlers
alike, the unfurling of the venerable dogwood blooms indicated the proper time
for planting corn.3
Dogwood has sometimes been called boxwood, referring to the
similar qualities between it and the European boxwood (Buxus sempervirens,
Buxaceae). Because it wears slowly and is very hard, dogwood was used to make
mill wheel cogs and the small parts of other wooden machinery that was
susceptible to wear. Forks, spoons, rulers, chisel and hammer handles, mallet
heads, and wooden vices are just a few implements the 19th-century woodworker
made from this durable material. Weavers have long used shuttles and bobbins
made from this wood.12
Chewing sticks, the forerunners of toothbrushes, were known
for helping maintain white teeth. Dogwood twigs are chief among the chewing
sticks in North America. William P.C. Barton (1786-1856), physician and medical
botanist, observed in his Vegetable Materia Medica of the United States:
The wood of the Cornus florida is much used by Dentists, in
the insertion of artificial teeth; and the young branches stripped of their
bark, and rubbed with their ends against the teeth, render them extremely
white. The creole negroes who inhabit Norfolk in Virginia in great numbers, are
in the constant practice of substituting the dogwood twigs, for a West Indian
shrub in cleansing their teeth. The striking whiteness of these, which I have
frequently observed, is a proof of the efficacy of the practice. The
application of the juice of these twigs to the gums, is also useful in
preserving them hard and sound.13
Barton’s more famous uncle, colonial physician Benjamin
Smith Barton, also extolled the value of flowering dogwood. “The ripe fruit, or
berries, infused in spirit or brandy, make an agreeable bitter,” he wrote. “Our
Indians employ an infusion of the flowers for intermittents [fevers]. The same
infusion has been recommended by some in flatulent cholic. I have used it as a
tea.”14
Historically, physicians in North America held dogwood bark
in high esteem as a potential antimalarial. Dogwood’s inner bark became a
preferred indigenous alternative to the high-priced and often-adulterated
Peruvian bark, Jesuit’s bark, or cinchona (Cinchona spp., Rubiaceae), the chief
source of the drug quinine.15 Dogwood bark, preferably that of the root, was
substituted for cinchona in the treatment of intermittent fevers (a telltale
symptom of malaria). Primarily used in the form of powdered bark or tincture,
dogwood’s effects were also considered astringent, tonic, and antiseptic. The
bark was most often used after being cured for a year, because the fresh bark
tends to irritate the stomach and bowels. During the American Civil War (1861-1865),
in the South, dogwood was used almost exclusively over cinchona due to lack of
availability of the latter.16 From 1820 through 1894, the inner bark of the
flowering dogwood was an official remedy in the USP.
Several recent studies have analyzed possible antiplasmodial
compounds from dogwood. Graziose et al. (2012) at Rutgers University looked at
the dried powdered bark extracted with 95% ethanol and found that
antiplasmodial-guided fractionation revealed eight compounds with moderate in
vitro antiplasmodial activity, none of which were effective enough to explain
the historical use of flowering dogwood as an antimalarial remedy. However,
they did show that several compounds possessed promising in vitro activity
against Leishmania parasites.17
A new iridoid glucoside (cornusoside A), four new iridoid
aglycones (cornolactones A–D), and 10 known compounds were isolated from C.
florida leaves collected at the University of Mississippi. The Cornus genus is
a rich source of iridoid glucosides with potential antidiabetic, antioxidant,
anti-inflammatory, anti-amnesic, and immunosuppressive activities.18 In
addition, cyanidin 3-O-galactoside and cyanidin 3-O-glucoside are the first
biologically active anthocyanins from dogwood fresh fruits to have been quantified.19
The white robe of dogwoods in bloom makes it one of the
fairest trees of North American forests. However, for four decades,
once-abundant populations of the fair dogwood have been decimated by a disease
known as dogwood anthracnose. The disease is caused by Discula destructiva, a
fungus first identified in 1991 and thought to have originated with kousa
dogwood (C. kousa) horticultural stock from Asia.20 Widely planted in North
American horticulture, the Asian kousa dogwood produces fruits that are not
eaten by North American song birds. With the extensive mortality of C. florida,
many birds and mammals throughout eastern North America are deprived of an
important fall food source.21
Sassafras — Sassafras albidum
“That sassafras tea was a very common beverage in my boyhood
days,” wrote Eclectic pharmacist John Uri Lloyd in 1911, “may be shown by the
following incident: I was traveling up the Ohio River on one of the palatial
steamers of other days, and the waiter asked a Kentuckian at my side who ordered
tea, ‘what kind of tea’ he wanted. ‘Store tea,’ he answered, ‘I kin get plenty
of sassafras at home.’”22
Perhaps no other tree holds such an important place in
American history. One of the first natural products from the New World,
sassafras (Sassafras albidum, Lauraceae) exports rivaled those of tobacco (Nicotiana
tabacum, Solanaceae). As a salubrious tea and a traditional “blood thinner,”
sassafras’ fame is unsurpassed. Sassafras has also been used as a controversial
“health food.” The sassafras story is one of fact, fallacy, and fortune — a
story that has yet to end.
The dried leaves of sassafras were used by native groups and
subsequently by Cajun settlers as a soup base. The leaves are powdered, then
sifted to remove stringy fibers. These dried and powdered leaves, which are
very mucilaginous and give soup a ropy consistency, are the base of the
traditional southern American dishes gumbo filé or gumbo zab and are added at
the end of preparation as a thickener. Agricultural chemist and inventor George
Washington Carver, DSc, PhD, of peanut (Arachis hypogaea, Fabaceae) and sweet
potato (Ipomoea batatas, Convolvulaceae) fame, said of sassafras leaf powder:
“It can be cooked with the soup, etc., or put in a salt shaker and placed on
the table to be used at will, like salt and pepper. It is most wholesome and
appetizing.”23
Sassafras tends to be more shrub-like in the northern part
of its range, typically growing up to 30 feet tall with a trunk up to a foot in
diameter. However, George B. Emerson (1846) described a sassafras tree in
Cambridge, Massachusetts, that was more than 60 feet tall and three feet in
diameter. “It was felled and its roots dug up, to allow a stone wall to run in
a right line,” he lamented. “Such pieces of barbarism are still but too common.
A tree so beautiful and lofty, of such rare dimensions, such an ornament to a
bare hillside, sacrificed to the straightness of a wall!”24
Sassafras albidum is a member of the laurel family
(Lauraceae). The North American S. albidum is one of three known species in the
genus.25 The other two are East Asian natives. Sassafras tzumu is indigenous to
Anhui, Fujian, Guangdong, Guizhou, Hubei, Hunan, Jiangsu, Sichuan, Yunnan, and
Zhejiang provinces and the Guangxi autonomous region in China, and it contains
approximately 1% essential oil with safrole as the primary component. Sassafras
randaiense is found on high mountains in broad-leaved evergreen forests in
central and southern Taiwan. All three species are very closely related.26
The first detailed record of sassafras and its healing
properties comes from writings of the Spanish physician Nicolás Monardes of
Seville (1574). Monardes’ records come not from personal experience or travels
to the Americas, but accounts from travelers and government records. Prior to
1574, sassafras had, for some years, been imported into Spain from its Florida
expeditions. The remaining French settlers from the French Huguenot immigrants
who settled Florida from 1562-1564 are said to have recommended sassafras to
the Spaniards to treat fevers, unwholesome drinking water, and other diseases
arising from the swamp miasma. The French first learned of the virtues of
sassafras from the native groups of the Florida peninsula.27
Sassafras was one of the first exports from American shores.
The Spaniards and French imported sassafras, or fennel wood, as it was known,
to the European continent before the English did. It was well known in Germany
by the 1580s. As early as 1585, a publication from Walter Raleigh’s second
excursion to America deemed sassafras a “merchantable commodity.” In June 1603,
an English merchant, Martin Pring, arrived on the American coast and sailed
south until he found a suitable place to collect sassafras. He loaded two
ships’ holds with bark and root, then set sail for England with his cache. By
1610, the root fetched a price better than 50 pounds sterling per ton. The 1618
London Pharmacopoeia proclaimed sassafras imports to be equal to those of
tobacco.28
One reason for its European popularity was its supposed
ability to cure syphilis. As American physician and botanist Jacob Bigelow
noted in 1818:
The bark and wood of the sassafras were formerly much
celebrated in the cure of various complaints, particularly syphilis,
rheumatism, and dropsy. Its reputation, however, as a specific in those
diseases, particularly the first, has fallen into deserved oblivion, while it
is now recognized only with regard to its general properties, which are those
of a warm stimulant and diaphoretic.28
The most well-known use for sassafras oil was in the
flavoring industry in which it was used to flavor root beer, candies, and
chewing gum. The chief chemical constituent of sassafras oil, safrole,
comprises 80-90% of the weight of the oil and is responsible for the
characteristic flavor of sassafras. Safrole is found in the essential oils of
at least 70 other plants, including some common culinary herbs, such as basil (Ocimum
basilicum, Lamiaceae), nutmeg (Myristica fragrans, Myristicaceae), and star
anise (Illicium verum, Illiciaceae).
Resulting from studies conducted on the effects of safrole
administered by injection in rats, a ruling published in the Federal Register
on December 3, 1960, prohibited the further use of safrole in foods. Laboratory
tests conducted by the US Food and Drug Administration (FDA) found safrole to
cause liver cancer in rats. At this point, the beverage industry voluntarily
withdrew safrole as a flavoring agent for root beer and related products.
According to Arthur O. Tucker, PhD, safrole is a
pre-hepatocarcinogen in humans (and dogs). It requires metabolic activation to
become a carcinogen, but by itself, safrole is not highly carcinogenic. The
leaves contain no or only trace amounts of safrole, by most reports, which is
mostly concentrated in the essential oil of the root bark. Safrole shares some
chemical similarities (and odors) with trans-Anethole found in anise (Pimpinella
anisum, Apiaceae) and estragole found in tarragon (Artemisia dracunculus,
Asteraceae), basil, and fennel (Foeniculum vulgare, Apiaceae), for example.29
In 1974, the FDA expanded and clarified the earlier law to
include the sale of sassafras root, bark, and leaves for the purpose of making
an herbal tea. The FDA argued that the water used to make tea was a “food” and
that the purpose of making sassafras tea was to extract safrole, the banned
flavoring agent, into water. The FDA thereby attempted to define a substance
used to make herbal tea as a “food additive,” subject to the Delaney Amendment
of the Food and Drug Act, which says essentially that any substance that causes
cancer (including in experiments on animals) cannot be added to food.30
Subsequently, the FDA seized a supply of a California herb
company’s sassafras and attempted to take them to court for selling it as an
herbal tea. The usual delays of such a court case resulted in the sassafras’
becoming moldy in the warehouse, and by the time the case finally came to trial
(three years later), the moldy sassafras was no longer fit for human
consumption, and it was destroyed. In protest of the FDA’s action, a token
handful of sassafras was tossed into Boston Harbor from the Boston Tea Party
Ships and Museum at a gathering of the then-fledgling, now-defunct Herb Trade
Association in July 1978.
The case of sassafras’ safety or potential to cause cancer
has never been satisfactorily resolved. Is there actually safrole left in a cup
of sassafras tea after it has simmered uncovered on low heat? Some believe the
FDA simply picked on sassafras as a way to apply food additive regulations to
the then-emerging herb industry of the 1970s. Herbs used for food purposes were
regulated under food additive laws at the time. If one ever went into an herb
shop and saw a package of sassafras labeled “not for food use,” that label
results from FDA regulations, rather than any inherent problem with that
particular lot of sassafras. It is legal to sell sassafras bark or leaves if
they are “safrole-free.”
Slippery Elm — Ulmus rubra
When the coming of spring is still a hopeful thought, the
russet downy buds of slippery elm (Ulmus rubra, Ulmaceae) unfold inconspicuous
petalless blooms, then set mature seeds, before most trees leaf out. The
slippery elm, or red elm, is the only one of the five or six species of North
American elms with rough, hairy twigs and fuzzy red buds. The silky yellow
wafer-like fruits seen on the tree from about late March into June are oval in
shape and roughly one-half to one inch broad. Unlike the fruits of other elm
species native to North America, the margins of slippery elm’s fruits are
entire or smooth-edged. Other species have a hairy fringe on the fruit’s
margins.
Ulmus is the old classical Latin name for elm trees. Rubra,
meaning “red,” refers to the rust color of the buds. “Elm” is the ancient name
from Anglo-Saxon, Celtic, Gothic, and Teutonic dialects, remaining unchanged in
modern English. Although U. rubra is the Latin name found in current botanical
manuals, many herb books list slippery elm under its old superseded Latin name,
U. fulva.
Slippery elm occurs in a variety of soils, from dry upland
types to moist, limey stream banks. The tree ranges from Maine through the St.
Lawrence Valley to the Dakotas, south to Texas and east to Florida. Like
American elm (U. americana), slippery elm is also susceptible to Dutch elm
disease (from the fungus Ophiostoma ulmi, formerly Ceratocystis ulmi).31
Charles Sprague Sargent, the first director of the Arnold Arboretum of Harvard
University, described slippery elm as a handsome, shapely, fast-growing tree in
cultivation. However, in 1895, he warned, “in public parks and streets its use
is to be avoided, for once its identity is established, it usually falls prey
to boys eager to devour the inner bark of the branches.”32
The inner bark, which is tawny- or buff-white in color, is
the “slippery” or mucilaginous medicinal and edible portion of the tree. In Materia
Medica Americana Potissimum Regni Vegetabilis (1787), one of the first works
devoted to American medicinal plants, Johann David Schoepf referred to it as
“salve bark.”33 European settlers were taught by indigenous groups to make an
infusion by soaking the shredded inner bark in cold water, and this was used as
a domestic remedy for fevers with diarrhea, and bowel afflictions. The inner
bark was widely used as a poultice for skin diseases and was commonly known to
many. The powdered inner bark makes a gel-like substance, similar to that of
arrowroot (Maranta arundinacea, Marantaceae), when stirred into warm water. The
polymath Constantine Samuel Rafinesque, writing in his Medical Flora or, Manual
of the Medical Botany of the United States of North America (1830), considered
that preparation useful for urinary and bowel complaints, as well as sore
throat, pneumonia, pleurisy, inflammation of the stomach and bowels, and
herpes. It was also valued as a nutritive, taken as a small spoonful with an
equal amount of sugar dissolved in water. Externally, he suggested that it
allays inflammation and provides speedy healing for ulcers, burns, skin
eruption, sores, scabs, and to extract the ball in the case of musket ball
wounds.34
In 1853, Thomas Meehan complained that the slippery elm
specimen at Bartram’s Garden outside of Philadelphia, although 50 feet high and
more than five feet in circumference, was nearly dead “owing to the bark having
been almost entirely stolen off for medicinal purposes.”35 In 2007, HerbalGram
reported on the theft of slippery elm bark from the Daniel Boone National
Forest in Kentucky, illegally stripped from the trees by poachers.36
Slippery elm is an FDA-approved nonprescription
(over-the-counter [OTC]) demulcent drug ingredient used for temporary relief of
minor discomfort, protection of irritated mucous membranes in the mouth, and
for sore throat. The product is a lozenge formed from agar or other
water-soluble gum base that contains 10-15% of slippery elm bark.
Unfortunately, both the FDA OTC drug monograph as well as the
ingredient-defining monograph in the USP call the ingredient “elm bark” rather
than “slippery elm bark,” the name by which it is has widely been known in the
botanical trade and literature for more than 200 years.36
Sweetgum — Liquidambar styraciflua
Fresh beaver activity marked a trail for a fall hike. A
small dam under construction made hiking difficult in a water-soaked thicket.
Fortunately, the beaver left a collection of neatly carved “walking sticks”
along the creek’s edge. Nearby stood a stand of old sweetgums girdled by a
beaver. The source of the genus name for the tree, Liquidambar, was in strong
evidence. At the top of the girdled scars were oozing drops of “liquid amber,”
moving like glaciers from the tree’s veins. It is this gum resin that provides
the tree’s product of commerce.
American sweetgum (Liquidambar styraciflua, Hamamelidaceae;
or separated into the smaller family Altingiaceae) is one of four or five
species historically placed in the genus, depending on the taxonomic treatment.
Two species are native to China (L. formosana and L. acalycina), and another
species (L. orientalis) is native to the western Mediterranean region,
particularly Greece and Turkey. American sweetgum grows from Connecticut, west
to Arkansas and beyond, then south to Guatemala, Honduras, and Nicaragua, with
the Central American populations about 500 miles disjunct from the southernmost
temperate forest populations.31,37 The genera Altingia, Semiliquidambar, and Liquidambar,
all of which are in the small family Altingiaceae, have recently been nested
within the genus Liquidambar, which combined contains 15 total species. The genus
is of interest to plant geographers because of the intercontinental disjunction
in temperate North America, West Asia, and montane areas of subtropical Asia
and Mexico.38
The balsamic oleoresin known as American styrax or storax is
the consistency of honey when fresh, but hardens to a soft amber-like substance
upon exposure to air. It has an aromatic, balsamic fragrance and a mild,
pleasant flavor, slightly bitter and warm. The color is more or less
transparent yellow, becoming cloudy and darker upon aging. It makes a good
chewing gum, known to many school boys a hundred years ago throughout the
tree’s range. Storax is the subject of an official monograph in the USP, with L.
orientalis and L. styraciflua listed as the source species.39
Early American naturalists, including Mark Catesby,
recognized the usefulness of the gum. In The Natural history of Carolina,
Florida and the Bahama Islands (1743), Catesby wrote:
From between the Wood and the Bark of this Tree issues a
fragrant Gum, which trickles from the wounded Trees, and by the Heat of the Sun
congeals into transparent resinous Drops, which the Indians chew, esteeming it
a Preservative of their Teeth: The Bark is also of singular use to them for
covering their houses, which has frequently given me an opportunity of
gathering the gum from Trees strip’d of their Bark, one of which would yield an
Hat full of Gum. This Gum smells so like the Balsam of Tolu, that it is not
easy to distinguish them.40
In his Collections for an Essay Towards a Materia Medica of
the United States (1801), Benjamin Smith Barton described some of the tree’s
uses:
The gum-resin which exudes from the Sweet-gum or
maple-leaved Liquidambar-Tree, the Liquidambar Styraciflua of Linnaeus,
deserves to be mentioned. The storax of the shops is thought to be the produce
of this tree: but perhaps this point is not yet quite ascertained. I am
informed that the produce of our tree has been used, with advantage, in
diarrhea. Some of our southern Indians mix the dried leaves with tobacco, for
smoking.41
American sweetgum was sometimes found in early American
pharmacies, mainly as a substitute for or adulterant of the Asian storax, which
is derived from oriental sweetgum (L. orientalis). Both were considered to have
the same properties, but the American sweetgum was little used by American
physicians.
The leaves of the tree have five to seven deep,
sharply-pointed lobes, similar to maple leaves. The prominent lower veins exude
a sweet fragrance when bruised or broken. In autumn, the leaves turn a deep
crimson red, yellow, or dull purple. Wyllie and Brophy (1989) identified
terpinen-4-ol as the major component of sweetgum leaf essential oil, coupled
with a low content of 1,8-cineole, suggesting it to be of similar chemical
composition to commercially viable Australian tea tree (Melaleuca alternifolia,
Myrtaceae) oil.42
In 2010, Martin et al. showed that sweetgum contains
significant quantities of shikimic acid, which is a medicinal compound used as
a precursor in the manufacture of the anti-influenza drug oseltamivir
(Tamiflu). Star anise from Asia is the current primary source of shikimic acid,
but supply shortages in 2005 prompted a search for other sources. Sweetgum,
considered a weed tree in southern pine plantations, yields upwards of 1.7 mg/g
of shikimic acid.43
Tulip Tree — Liriodendron tulipifera
Few North American trees surpass the tulip tree (Liriodendron
tulipifera, Magnoliaceae) for its great size and long, straight trunk. This
member of the magnolia family has been known as yellow poplar, white wood,
canoe tree, tulip poplar, and tulip tree. The genus name, Liriodendron, is
derived from two Greek words meaning “tree with lily-like flower.” The tree’s
northern limit stretches to the southern extremity of Lake Champlain, though
the main part of its range is in the Ohio River Basin. From Vermont in the
north, its range extends south to Rhode Island, west to the southern shores of
Lake Michigan, southward to Arkansas and east to northern Florida. The tree
attains its greatest growth in the deep, fertile soils of river bottoms,
borders of large springs, creeks, and swamps, and rich mountain embankments.44
During the Lower Cretaceous Period (about 65.5-145.5 million
years ago), the genus Liriodendron was widespread across North America, Europe,
and Asia. Botanists long thought that the tulip tree was the only living
species of this ancient genus, but much to their surprise, a Chinese species
was discovered in 1875 and named in 1903 by Charles Sprague Sargent.45 Liriodendron
chinense, the Chinese tulip tree, is from central China along the Yangtze River
Valley in a narrow range in northern Jiangxi and western Hubei provinces.
For 300 years, since the discovery of American ginseng (Panax
quinquefolius, Araliaceae), plant geographers have been aware of a classical
pattern of plant disjunctions between eastern Asia and eastern North America.
The floras of the eastern portions of both continents harbor dozens of closely
related species not found elsewhere. Chief among these “disjunct” plants are
trees. Upwards of 120 genera of eastern North American plants are involved in
this disjunct pattern, about half of which are woody plants, including the
genera Sassafras and Liriodendron.46,47
Tulip tree was among the early remedies to be passed along
from native groups to early European settlers. Pennsylvania Germans used a
decoction prepared from the bark of the tulip tree as a remedy for toothaches.
The hot infusion was poured into the marrow of the toothache as an anodyne
(painkiller).
In 1830, Rafinesque wrote: “The Cherokee Indians used the
leaves in a poultice for sores and headache, and the ointment of the leaves for
inflammation; that the seeds are laxative, and that the extract of the bark is
a useful remedy for syphilitic ulcers of the nose.”48
Native groups of North Carolina are reported to have used an
ointment from the buds of the tree as a remedy for burns and scalds. Nightmares
resulting from bad cookery, late suppers, and irregular hours were treated by
Cherokee medicine men with a formula that included a syrup of the tulip tree,
when the preferred remedy, rattlesnake fern (Botrychium virginianum,
Ophioglossaceae) was unavailable. The bark of the Chinese tulip tree has also
been used to break fevers.49
In Schoepf’s Materia Medica Americana, he recognized the
bark, root, leaves, and seed of the tulip tree as remedies. The bark and root
were used in tincture form for fevers and rheumatism. The seeds were used as a
very mild laxative. The fresh leaves were used in ointments for gangrene and
inflammation.50
The bark, like that of dogwood, was used to some extent as a
substitute for cinchona to treat malarial fevers. A physician, J.T. Young,
addressed a letter to Governor Clayton of Delaware in 1792, expressing his
belief in the value of the bark in intermittent fevers and as a sure cure for
worms. Later, during the Civil War, tulip tree was one of the remedies used in
Confederate hospitals as a substitute for cinchona. In Confederate hospitals, a
compound fluidextract for the treatment of malaria was prepared from the barks
of the tulip tree, dogwood, and black willow (Salix nigra, Salicaceae).46
Francis Peyre Porcher (1863), in his Resources of Southern
Fields and Forests, noted:
The powdered bark in syrup is given to children who are liable
to convulsions and worms, to promote their expulsion, and to strengthen the
tone of the digestive organs. The bark should be pulverized and bottled. We
have employed a strong infusion of the bark and root of this plant as an
anti-intermittent, among a number of negroes and are much pleased with its
efficiency.51
American physicians used the bark as a stimulant tonic, with
diaphoretic qualities. In addition to being substituted for cinchona, it was
also used as a gentle stimulant of the digestive system, gout, and externally
as a wash in chronic rheumatism. It was also used as a domestic remedy for some
intestinal disorders such as diarrhea and dysentery, as well as colic and
worms. Though little used by the established medical profession, the bark was
an official remedy of the USP from 1830 to 1880.46
This relic of ancient forests, though today serving
primarily as an ornamental tree, provided inhabitants of this continent with
material and medicine for centuries. At least 17 compounds from the bark, stems,
and leaves (including lignans, aporphine alkaloids, coumarins, sesquiterpenes,
cyclitols, phytosterols, and benzenoids), some with antioxidant, cancer
chemopreventive, and tyrosinase-inhibiting activities, have been identified.52 Hidden
in its chemical secrets may be important compounds from which future products
could be derived.
Steven Foster is an author, photographer, and herbalist, and
he serves on the Board of Trustees of the American Botanical Council. His most
recent book is the third edition of the Peterson Field Guide to Medicinal
Plants and Herbs of Eastern and Central North America (Houghton Mifflin
Harcourt, 2014), which he co-authored with James A. Duke, PhD.
References
- Sargent CS.
The Silva of North America: A description of the trees which grow naturally in
North America exclusive of Mexico. Boston, New York: Houghton, Mifflin and
Company. 1895; Vol. 7, p. 123.
- Hammon
Products Company. Hulling and Buying Locations. Available at:
https://black-walnuts.com/discover-harvesting-and-hulling/hulling-and-buying-locations/.
Accessed October 8, 2017.
- Foster S,
Duke JA. Peterson Field Guide to Medicinal Plants and Herbs Eastern and Central
North America. 3rd ed. Boston, New York: Houghton Mifflin Harcourt; 2014.
- Griffith
RE. Medical botany; or, Descriptions of the more important plants used in
medicine, with their history, properties, and mode of administration.
Philadelphia: Lea and Blanchard; 1847; p. 590.
- Culbreth
DMR. A Manual of Materia Medica and Pharmacology. Philadelphia, PA: Lea
Brothers & Co.; 1906.
- Duke JA. CRC
Handbook of Nuts. Boca Raton, FL: CRC Press, Inc.; 1989.
- Wenzel J,
Storer Samaniego C, Wang L, et al. Antioxidant potential of Juglans nigra,
black walnut, husks extracted using supercritical carbon dioxide with an
ethanol modifier. Food Sci Nutr. 2017;5(2):223-232.
- Hammon
Products Company. Nutshell FAQs. Available at:
https://black-walnuts.com/view-nutshell-products/nutshell-faqs/#. Accessed
October 8, 20171017.
- Vestal PA,
Schultes RE. The Economic Botany of the Kiowa Indians. Cambridge, MA: Botanical
Museum; 1939; p. 21.
- Mooney J. The Swimmer Manuscript. Washington, D.C.: United
States Government Printing Office; 1932; p. 120.
- Camara CRS, Schlegel V. A review on the potential human
health benefits of the black walnut: A comparison with the English walnuts and
other tree nuts. International Journal of Food Properties. 2015;19:2175-2189.
- Emerson GB. A report on the trees and shrubs growing
naturally in the forests of Massachusetts. Boston, MA: Dutton and Wentworth;
1846.
- Barton WPC. Vegetable Materia Medica of the United States.
Vol. 1. Philadelphia, PA: M. Carey & Son; 1817; pp. 55-56.
- Barton BS. Collections for an Essay Towards a Materia Medica
of the United States. Philadelphia, PA: Printed for the Author. 1798; p. 12.
- Walker JM. An Experimental Inquiry into the Similarity in
Virtue Between the Cornus florida and Sericea and the Cinchona Officinalis of
Linnaeus together with an Inquiry into the Modus Operandi of Astringent
Vegetables in Preventing the Putrefactive Fermentation. Philadelphia, PA:
Printed for the Author by H. Maxwell; 1803.
- Porcher FP. Resources of the southern fields and forests,
medical, economical, and agricultural: being also a medical botany of the
Confederate States; with practical information on the useful properties of the
trees, plants and shrubs. Charleston, SC: Steam-power Press of Evans &
Cogswell; 1863; pp. 59-62.
- Graziose R, Rojas-Silva P, Rathinasabapathy T, et al.
Antiparasitic compounds from Cornus florida L. with activities against Plasmodium
falciparum and Leishmania tarentolae. J Ethnopharmacol. 2012;142(2):456-461.
- He Y, Peng J, Hamann MT, West LM. An Iridoid Glucoside and
the related aglycones from Cornus florida. J. Nat. Prod. 2014:77(9):2138-2143.
- Vareed SK, Reddy MK, Schutzki RE, Nair MG. Anthocyanins in Cornus
alternifolia, Cornus controversa, Cornus kousa and Cornus florida fruits with
health benefits. Life Sci. 2006;78(7):777-784.
- Oswalt CM, Oswalt SN. Documentation of significant losses in
Cornus florida L. populations throughout the Appalachian ecoregion. Internal
Journal of Forestry Research. 2010;2010:1-10.
- Rossell IM, Rossell CR, Hining KJ, Anderson RL. Impacts of
dogwood anthracnose (Discula destructiva Redlin) on the fruits of flowering
dogwood (Cornus florida L.): implications for wildlife. The American Midland
Naturalist; 2001; 146(2);379-387.
- Lloyd JU, Lloyd CG. History of the Vegetable Drugs of the
Pharmacopeia of the United States. Bulletin of the Lloyd Library, Pharmacy
Series No. 4. 1911; pp. 77-78.
- Carver GW. Nature’s garden for victory and peace. No. 43.
Revised and reprinted ed. Tuskegee, AL: Tuskegee Institute; 1942; p. 16.
- Emerson GB. A report on the trees and shrubs growing
naturally in the forests of Massachusetts. Boston, MA: Dutton and Wentworth;
1846; p. 323.
- Flora of North America Editorial Committee, ed. Sassafras. Flora
of North America North of Mexico: Magnoliophyta: Magnoliidae and Hamamelidae.
Vol. 3. New York, NY: Oxford University Press; 1997.
- Wu Z, Raven P, H., Hong D, eds. Sassafras. Flora of China:
Menispermaceae through Capparaceae. Vol. 7. Beijing and St. Louis: Science
Press and Missouri Botanical Garden Press; 2008; 159-16.
- Lloyd JU. Historical Story of Sassafras. The Western
Druggist. 1898(November):3-16.
- Bigelow J. American medical botany; being a collection of
the native medicinal plants of the United States, containing their botanical
history and chemical analysis, and properties and uses in medicine, diet and
the arts. Vol 2. Boston, MA: Cummings and Hilliard. 1818; p. 145.
- Tucker AO, Debaggio T. Sassafras. In: The Encyclopedia of
Herbs. Portland, OR: Timber Press; 2009; pp. 454-456.
- Segelman AB, Segelman FP, Karliner J, Sofia RD. Sassafras
and herb tea. Potential health hazards. JAMA. 1976;236(5):477.
- Flora of North America Editorial Committee, ed. Ulmus. Flora
of North America North of Mexico: Magnoliophyta: Magnoliidae and Hamamelidae.
Vol. 3. New York, NY: Oxford University Press; 1997.
- Sargent CS. The Silva of North America: A description of the
trees which grow naturally in North America exclusive of Mexico. Vol. 7.
Boston, MA, and New York, NY: Houghton, Mifflin and Company. 1895; p. 54.
- Lloyd JU, Lloyd CG. History of the Vegetable Drugs of the
Pharmacopeia of the United States. Bulletin of the Lloyd Library, Pharmacy
Series No. 4. 1911; p. 88.
- Rafinesque CS. Medical Flora, Or Manual of the Medical
Botany of the United States of North America. 2 Vols. Vol. 2. Philadelphia, PA:
Atkinson and Alexander, 1830; p. 271.
- Meehan T. The American handbook of ornamental trees. Philadelphia,
PA: Lippincott, Grambo, and Co.; 1853; p. 237.
- Cavliere C. Illegal stripping and conservation of slippery
elm trees. HerbalGram. 2007;74:54-61.
- Wu Z, Raven P, eds. Flora of China: Menispermaceae through
Capparaceae. Vol. 7. Beijing, China, and St. Louis, MO: Science Press and
Missouri Botanical Garden Press; 2008.
- Ickert-Bond SM, Wen J. A taxonomic synopsis of Altingiaceae
with nine new combinations. PhytoKeys. 2013(31):21-61.
- Convention U. The United States Pharmacopeia & The
National Formulary; USP 35 NF 30. 2012. Rockville, MD: United States
Pharmacopeial Convention, Inc. 2011; 4689.
- Catesby M. The natural history of Carolina, Florida and the
Bahama Islands: containing the figures of birds, beasts, fishes, serpents,
insects, and plants: particularly, the forest-trees, shrubs, and other plants,
not hitherto described, or very incorrectly figured by authors: together with
their descriptions in English and French: to which, are added observations on
the air, soil, and waters: with remarks upon agriculture, grain, pulse, roots,
&c.: to the whole, is prefixed a new and correct map of the countries treated
of. Vol 2. London, UK: Printed at the expense of the author. 1743.
- Barton BS. Collections for an Essay Towards a Materia Medica
of the United States. Part 1, 2nd ed. Philadelphia, PA: Printed for the Author.
1801; p. 16.
- Wyllie SG, Brophy JJ. The leaf oil of Liquidambar
styraciflua. Planta Med. 1989;55(3):316-317.
- Martin E, Duke J, Pelkki M, Clausen EC, Carrier DJ. Sweetgum
(Liquidambar styraciflua L.): extraction of shikimic acid coupled to dilute
acid pretreatment. Applied Biochem Biotech. 2010;162(6):1660-1668.
- Lloyd JU, Lloyd CG. Liriodendron tulipifera. Drugs and
Medicines of North America. Bulletin of the Lloyd Library. Reproduction Series.
1931;2(9):2-21.
- Sargent CS, Arboretum. Liriodendron chinense. Trees and
shrubs: illustrations of new or little known ligneous plants, prepared chiefly
from material at the Arnold Arboreum of Harvard University. Boston, MA:
Houghton, Mifflin. 1903; part III: 103.
- Parks CR, Miller NG, Wendel JF, McDougal KM. Genetic
divergence with the genus Liriodendron (Magnoliaceae). Ann Missouri Bot Gard.
1983;70:658-666.
- Wood CE. Morphology and phytogeography: the classical
approach to the study of disjunctions. Ann Missouri Bot Gard. 1972;59:107-124.
- Rafinesque CS. Medical Flora, Or Manual of the Medical
Botany of the United States of North America. Vol. 2. Philadelphia, PA:
Atkinson and Alexander, 1830; p. 90.
- Foster S. Benevolent Trees: A Woody Plants Herbal
(unpublished).
- Schoepf JD. Materia Medica Americana Potissimum Regni
Vegetabilis Erlangae. 1786; reprint ed., Bulletin of the Lloyd Library,
Reproductions Series, No. 3, Bulletin No. 6; 1903.
- Porcher FP. Resources of the southern fields and forests,
medical, economical, and agricultural: being also a medical botany of the
Confederate States; with practical information on the useful properties of the
trees, plants and shrubs. Charleston, SC: Steam-power Press of Evans &
Cogswell; 1863; p. 90.
- Li WJ, Lin YC, Wu PF, et al. Biofunctional constituents from
Liriodendron tulipifera with antioxidants and anti-melanogenic properties. Int
J Mol Sci. 2013;14(1):1698-1712.
|