Are you a proud green-thumbed pharma-“nerd” looking for a statement garden this summer?
Are you a proud green-thumbed pharmanerd who is looking for a statement garden? Below are 9 plant-derived natural products appropriate for temperate and tropical pharmacy-themed gardens. The tendency toward pest (e.g. deer and rodents) resistance is an added advantage to a pharmaceutical statement garden. Use these often toxic natural sources at your own risk. I recommend growing these plants as a curiosity only.
The northern two-thirds of the lower 48 United States, Canada’s coasts and Great Lakes regions encompass temperate North America for gardening purposes. These areas experience freezes every winter but lack the permafrost found in alpine, tundra, and taiga regions. “Tropical” can include the Gulf Coast but southern Florida and the Hawaiian Islands more predictably avoid frosts.
Temperate Garden Plants
Europeans have used willow bark for pain relief since the Ancient Greeks. Native Americans of the present-day northeastern US used sweet birch (Betula lenta) for salicylic acid harvesting before the importation of Eurasian willows. Multiple willow and birch species are native to North America streambanks and other moist spaces. Some birch species are small trees (20 feet tall at maturity) ideal for tight spaces.
Manufacturers can produce aspirin semisynthetically from natural salicylic acid but often produce aspirin from phenylalanine. Semi-synthetic production is simple; in fact, I produced aspirin during tabletop lab sessions in high school and college every year for 4 years straight. Bayer developed aspirin in the late 19th century for less stomach upset and bitterness than salicylic acid. The addition of the acetyl group to salicylic acid surreptitiously provides aspirin its durable antiplatelet effects.
Avoid bonafide birch beer/syrup consumption in children (Reye’s syndrome risk) and use caution if asthmatic or on blood thinners. Essentially, consider the methyl salicylate in these products like aspirin.
Gaultheria procumbens is a small evergreen shrub on shady acidic woodland soils (similar conditions as azaleas and blueberry plants) with attractive flowers and edible fruit. This eastern North American species is one of many species called wintergreen that share a menthol-like smell. Native Americans used the leaves topically for minor aches and pains and colonial-era apothecaries used leaf extracts as a salicylate source.1
Galanthus was the source of medical galantamine when first used as a non-depolarizing muscle relaxant antagonist and when researchers identified its potential in Alzheimer’s disease treatment. However, commercial-scale production of galantamine for Alzheimer’s has come from a synthetic process since the 1990s.2
This natural source of galantamine is a flowering bulb of cool woodlands flowering in late winter and early spring. Gardeners often grow snowdrops for their early-season beauty regardless of the pharmaceutical association. This is one of the least toxic plants on this list yet typical garden pests rarely bother it.
Foxglove is a natural source of cardiac glycosides (e.g. digitoxin) used today in heart failure and more conditions in the past. Digitalis toxicity, specifically its xanthopsia adverse effect, is a possible explanation for Van Gogh’s yellow period but his doctors denied prescribing digitalis for his seizures (standard of care at the time). Oddly Van Gogh included digitalis in the hand of the eponymous physician for his yellow period work “Portrait of Doctor Gachet”. Digitoxin has little medical use presently and its related digitalis-derived compound digoxin is progressively less popular over time due to its narrow therapeutic index.
Foxgloves are biennials (flowers the second year, sets seed, then dies) and perennials with attractive flowers that die back to the ground every year. These plants are cardiotoxic and spread somewhat aggressively in moist woodlands. Use caution to avoid accidental consumption of any plant matter by children, pregnant women, and pets.
This plant is a natural source of the antimuscarinic medication atropine and its namesake. Extemporaneous production of antidotes is inappropriate for emergency situations such as nerve agent, muscarinic mushroom, or pesticide exposure.
Take steps to prevent accidental exposure to pets and children (this plant earns its common name). The best prevention is avoidance. I suggest keeping this plant inside a locked fenced-in area away from food crops, livestock, and attractive objects to children and pets. The sap is a skin irritant, like its nightshade family member tobacco, therefore use gloves and wash your hands after handling.
Atropos is a Fate from Greek mythology in charge of ending lives; a fitting choice for a deadly plant. Fashionable ladies of past centuries used deadly nightshade extracts to dilate their pupils (belladonna meaning “pretty lady”).
People suffering from musculoskeletal aches and pains (e.g. osteoarthritis, strains, and sprains) may use capsaicin over-the-counter remedies for temporary pain relief. Topical capsaicin for possible post-herpetic neuralgia should follow contact with a medical professional. Capsaicin is well-tolerated but users should wash their hands thoroughly after use before touching their eyes, genitals, or other mucous membranes and sensitive skin regions.3
The heat “distraction” may be a successful example of homeopathy but capsaicin interferes with the action of Substance P as well. A common misunderstanding is that the “P” in Substance P stands for pain but it is ubiquitous and multi-functional, similarly the “B” in B cells refers to a bird’s bursa rather than bone, but Substance P does have a pro-pain effect.
Spicy (hot) peppers are tender perennials often grown as annuals during warm months across much of the continental United States. Capsicum species are native to tropical regions of the Americas. Capsaicin causes the “heat” of peppers therefore bell peppers have little of it. A distantly related plant (Piper nigrum) from India produces black pepper. The juxtaposition of “cool” plants containing salicylates and menthol with this “hot” plant is an attractive design element as well.
Do not consume or apply to the skin any other part of the plant except the fruits because peppers are a member of the nightshade family. The FDA provides no indications for capsaicin internal use although oral capsaicin may have complementary and alternative medicine potential and of course peppers are food. Capsaicin worsens the symptoms of inflammatory bowel disease and irritable bowel syndrome.3
Tropical Garden Plants
The FDA considers topical use safe for a myriad of skin conditions but aloe’s efficacy is unclear. However its stimulant laxative use is NOT FDA approved and the FDA required all such products removed from the market in 2002.4
Aloe vera cultivation is a $13 billion business started by Arabian traders along major trade routes 2 millennia ago. The Aloe species all have succulent leaf pulp with moisture-retentive properties. But Aloe vera is the only broadly cultivated species and the sole member absent from the CITES list of endangered species.5
Aloe vera is best grown in freeze-free desert climates (similar to its native land of Arabia) or indoors in cactus soil. Growers should collect material from the outer leaves and can cut the tips off large leaves but the tip will not regenerate.
The FDA recommends strictly topical use for skin conditions such as pruritus, mild burns, and arthritis pain. Camphor is a component of paregoric (camphorated tincture of opium) and menthol decongestant ointments. Suspected plant consumption is reason to call the national toll-free Poison Help hotline (1-800-222-1222) for assistance. Observe the person after exposure and position to maintain a clear airway if the affected person is unconscious.
The camphor tree is a 70-foot evergreen tree with fragrance upon crushing leaves and peeling bark. The kitchen herb rosemary contains small amounts of camphor as well. Commercially-available camphor is often produced from turpentine oil (itself made from pine resin). The University of Florida reports this species is invasive in the southeastern US.6 Check with local government and homeowner’s association before planting.
Senna leaves are the complementary and alternative medicine laxative companion to pharmaceutical grade senna (+/- docusate) formulations. Senna ingestion can reduce nutrient and medication absorption much like senna pharmaceuticals. Consumers have abused senna for weight loss purposes although inducing diarrhea is an uncomfortable weight loss plan to even imagine.
These legume plants produce fruit resembling an extremely large pea pod. Accidental consumption of meager amounts cause severe diarrhea especially among pets and children. Native temperate species are also available but unrelated to senna’s historical use.
Consumers use castor oil as a laxative and to induce labor (although efficacy for the latter is unclear). Kolliphor EL, previously Cremophor EL, is a derivative of castor oil included in emulsion intravenous products.
National Fascist Party enforcers, the British Raj, and (hopefully) well-meaning parents alike have forced political opponents, prisoners, or their (dear…precious) children to consume castor oil to exact diarrhea-based punishment.
Distinct from castor oil’s diarrheagenic effects, a measly 1 mg of ricin can kill the average adult in a few days by dehydration via profuse vomiting and diarrhea beginning within a few hours of ingestion. Just one bean, if chewed, can kill a small child. Snip and dispose the flowers off this plant in the garden to prevent bean formation.7 Avoid this plant if you have small children or grandchildren.
Take steps to prevent accidental exposure to pets and children because ricin is one of the deadliest poisons known. In fact, the assassination of Georgi Markov with a pellet embedded in the tip of an umbrella illustrates the extreme potency. However, medicinal castor oil lacks water-soluble ricin.7 Ricin possession is illegal but bans on whole beans are rare although you should check with your municipality and/or homeowners’ association before planting.
Two Special Cases
Two plants you should not attempt to grow are opium poppies (Papaver somniferum) and cannabis for obvious reasons. The Controlled Substances Act forbids unregulated cultivation of these species in the USA (listed in Schedule II).8 Although other poppy species are popular ornamentals particularly in Mediterranean climates (e.g. southern California).
Cannabis plants were ubiquitous in vacant lots throughout New York Ciy and in then more rural Brooklyn and Queens until a 1951 crackdown.9 The symbolism of the poppies scene in The Wizard of Oz (1939) has become less obvious with the advent of controlled substances. Little kids and many adults are unaware that the Wicked Witch of the West is sedating the protagonists with magical opium. Eliminating heroin producers in Afghanistan would be decidedly easier if opium poppies had the ability to sedate people through sight.
Gardeners of these medicinal plants should use common methods of prevention to protect children and pets. Fencing (including securing the bottom to prevent entry by dogs), supervision, and separation from food crops prevent accidental exposures. Call the Poison Help hotline in cases of possible poisoning with the affected person's age, weight, and health conditions, the plant’s identity, and the time and amount of exposure.10
Planting a pharmacy-themed garden improves your property’s attractiveness, is a fun past-time, and a conversation starter. These are just a few medicinal plants you can grow in temperate and tropical climates with interest throughout the year.