Handle Tropical Plants with Caution

by Tara A. Spears

As I was recently playing in the dirt by putting out new plants, I remembered the shock I felt when I first learned that so many tropical species are toxic.  When I first moved to Florida, I had immediately begun filling my new yard with dozens of species that I wasn’t familiar with-it was such a gardening adventure!  I noticed that my hands were getting rashes, my nose and eyes would water when I trimmed certain plants, and smoke from burning the native vegetation made me nauseous. When I attended local garden club meetings, I asked the veteran gardeners about it.  I was speechless to learn that such beautiful flowering plants were toxic and that some species were lethal.

Plant Defense:    

Plants can’t run, fight, or hide, so they make themselves inedible with poisons, otherwise the plants would get completely eaten up and become extinct. Animals that live on plants- think of the voracious eaters such as iguanas- have some degree of resistance to plant poisons, but humans mostly lack such resistance. Plants that are consumed as salads have been selected and grown for their lack of poisons but such plants cannot survive on their own without human protection. According to horticulturist Devin Dupre-Neary, poisonous plants are laced with alkaloids or chemicals that cause anything from mild irritation of the skin, to burning and paralysis of internal organs, to the fatal breakdown of body functions. Humans get vegetation poison in their system through contact or by ingestion of poisonous plant tissue. While most plant contact is non-lethal, it still can be dangerous and even cause blindness in extreme cases. Ingestion of toxic vegetation can cause an upset stomach, or in rare cases, death. It is important to know how to identify and avoid contact with poisonous tropical plants.

Living with Toxic Beauty:  

It’s not impossible to still include this category of potentially harmful plants in your home garden-it’s a matter of awareness. After all, commercial growers and retail outlets worldwide sell these plants. Education and prevention are the best tools for avoiding plant and shrub poisoning. Teach your family and others about these plants, how to identify them, why they are dangerous, and to avoid contact with them. Know the plants in your landscape. I have most of the toxic species in my garden, with no ill effect because I handle them with common sense modifications, such as wearing gloves and not getting any sap in my eyes or mouth. However, since I have preschool-age granddaughters, I do not have the most lethal types in my yard just to be sure that the inquisitive toddlers won’t be exposed.  Those who have pets, particularly cats, need to be aware that this group of tropical plants can also be harmful to animals.  If your dog or cat is one that likes to chew on plants, it’s wise to avoid putting this type of plant in your landscape.  

Partial List of Toxic Tropical Plants: 

(All are excellent growers in the Riviera Nayarit climate; most are sold as annuals/houseplants north of the border.)

Allamanda: 

The plants either climb nearby shrubs and trees or grow as shrub-like mounds on the ground. All parts of the plant are poisonous. If cut or damaged, the foliage oozes white latex that can irritate the skin.

Aloe Vera:  

Yep, this medicinal plant has a pulpy inside that is an excellent topical skin treatment, however, the skin of the leaves are very toxic if eaten.

Anthurium or Flamingo lily:

Eating the flower or leaves causes painful blistering of the mouth and throat.

Avocado Tree: 

The leaves, fruit skin, seeds, and bark are poisonous if ingested.

Caladium or Angel’s Wings: 

Eating will cause severe irritation to mouth and may also irritate the G.I. tract causing cramping or diarrhea.

Castor bean, castor oil plant, Palma Christi:

This semi-woody plant grows wild in Guayabitos/La Penita area.  All parts of the plant are very poisonous to eat, especially the beanlike seeds that grow near the top of the star-like leaves. Definitely avoid this one in a home garden.

Cowhage, cowitch:   

This tropical vine-like flowering plant has oval leaves in groups of three, hairy spikes of flowers, and brown hairy seed pods. Contact with the pods and flowers causes irritation and blindness if it gets in the eyes.

Croton: 

Chewing the bark or roots of this poisonous plant can cause burning of the mouth. In addition, some people get eczema after repeated exposure and contact with the skin.

Jimson Weed, datura, thorn apple, stinkweed:     

All parts of Jimson weed are poisonous, and when eaten can cause abnormal thirst, vision distortions, delirium, incoherence, coma and is often fatal

Kalanchoe Coral plant, Physic nut:   

This small shrub is another no-no for a home garden, unless you are planning to off someone. The ancient Indio medicine men used the nut in ceremonies due to its psychedelic properties; the oil of the seeds is violently purgative.  With this member of the deadly Spurge (Euphorianceae) plant family, all parts of the shrub are poisonous if eaten. 

Lantana: 

Common tropical that likes the hot sun and has charming clusters of multicolored flowers besides a unique scent. Any part of this shrubby plant is poisonous or even fatal if eaten.  Some individuals get contact dermatitis from lantana.

Manchineel:  

Tall tropical member of the spurge family has shiny leaves, small greenish flowers, and yellow green fruits. Extremely toxic!  Contact with any part of the plant can cause severe dermatitis in most people within minutes.  Water dripping from leaves and smoke from burning also can cause rapid irritation. No part of this tree should be around food or ingested.

Mango:     

The sap, leaves, green unripe fruit, and the petiole and skin of the ripe fruit contain cross-reactive oleoresins that can cause contact dermatitis (rashes) in persons already highly sensitive to Poison Ivy. Smoke from burning the plants can cause eye and respiratory irritation, so Mango wood should not be used as firewood.

Moonflower, Angel trumpet plant, Hell’s Bells: 

This elegant and beautiful poisonous tropical is a popular garden flower.  Moonflower contains alkaloids that have caused poisoning and death in humans and animals. This member of Datura belongs to a group of plants known as “Witches Weeds” because it has been used in various potions and brews to commit suicide and murder.      

Night Blooming Jasmine:

A wonderful tropic vine that attracts large hummingbird moths besides being one of the most fragrant wild plants that releases a sweet scent at night. The entire plant and especially the berries are poisonous to humans and other mammals, but not to birds.

Oleander: 

One of my favorite tropical shrubs that can grow up to 15 feet (6 meters) tall boasts continuous clusters of blossoms coupled with straight, dark green leaves. This woody shrub is excellent for back-of-the-garden drama or spiffing up a view of a fence.  Available in five colors, it bears brown pods of seeds. Extremely Poisonous! Every year that I had lived in coastal Florida there were incidences and fatalities from unknowing people using the wood to build a beach fire or using the wood for hotdog roasting. The milky sap is lethal, and burning the wood for cooking creates poisonous fumes that taint food. This is one plant I don’t have in the yard until my grandkids are older.

Oyster Plant, Tricolor Rhoeo:   

This low growing tropical is highly salt tolerant and adapted to the long dry season, making it very popular for coastal gardens. The sap can cause dermatitis and should not be eaten.

Philodendron: 

A popular house plant in northern latitudes, this plant gets humungous in its native tropic environment.  Terrific climbers that enhance palm trees and shady areas, philodendron contain oxalates that can cause poisoning in humans and pets.  Contact with the sap can cause inflammation, redness, and itching. Ingestion will quickly cause painful burning and swelling of lips, mouth, tongue, and throat.

Plumbago, Frangipangi:

Who would imagine that these tropical beauties with the exotic fragrance are totally poisonous? Anyone who has visited the Western Pacific islands knows that the famous Singapore Plumeria flowers are made into leis or worn tucked behind the ear so that their perfume can be enjoyed by the wearer. Beware of the milky latex sap because it is poisonous and can irritate the skin; do not ingest any part of the plant.

Poison ivy and Poison oak:   

This nasty plant grows all over the North American continent, so those that suffer from contact dermatitis still need to be watchful in the tropic vegetation. The two plants are similar with compound leaves with three leaflets. Poison ivy grows as a vine, climbing by red feeder roots, while poison oak grows like a bush.  All parts of the plant, at all times of the year, can cause serious contact dermatitis.

Stinging Spurge:  

This obnoxious plant prefers low altitude tropics.  It is all over the undeveloped lots in Guayabitos as I discovered when shopping for property. This small bushy plant has white blossoms and milky latex sap besides being entirely covered with long stinging hairs. Even a slight touch of any part of the plant causes severe burning and pain, blistering, and insensitivity of the affected skin area for a day or longer. Believe me, it only takes one encounter and you learn to watch for it

Tumpet vine, trumpet creeper: 

This woody vine with its pea-like fruit capsules, compound toothed leaves and charming flowers is a great addition to a tropical yard. It does cause contact dermatitis, however.

Since adults do not have a tendency to chew on leaves, most of the tropical listed are not a big risk to have in your yard.  Just to be safe, though, wear gloves when working around these plants, and wash your hands with soap and water after contact.  Always seek medical attention for pets or individuals that ingest any of the toxic plants.