Poisonous Plants of North America

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The poisonous plants of North America effect individuals by skin contact, ingestion, absorption or inhalation. The symptoms are painful skin eruptions after contact, internal poisoning when ingested, and coughing or sneezing when inhaled into the lungs. Some edible plants have deadly relatives like the carrot family with hemlocks and cows parsnip. Knowing positive identification of common poisonous plants can help eliminate the danger of accidental poisoning. ------------------------------------------------------------ --------------------------------------------- Stinging Nettle Urtica Dioica L. in the Nettle family also called Common Nettle gorws up to about 1.5 meters tall, perennial shrub with unbranched upright stem, with green blossoms july to October. The whole plant mainly the stems have hundreds of needle like stinging hairs that cause skin eruptions. Once dried or slightly cooked the entire nettle plant is edible. This is a fully matured Stinging Nettle. This is a young Stinging Nettle plant.

Transcript of Poisonous Plants of North America

Page 1: Poisonous Plants of North America

The poisonous plants of North America effect individuals by skin contact, ingestion, absorption or inhalation. The symptoms are painful skin eruptions after contact, internal poisoning when ingested, and coughing or sneezing when inhaled into the lungs. Some edible plants have deadly relatives like the carrot family with hemlocks and cows parsnip. Knowing positive identification of common poisonous plants can help eliminate the danger of accidental poisoning.---------------------------------------------------------------------------------------------------------Stinging NettleUrtica Dioica L. in the Nettle family also called Common Nettle gorws up to about 1.5 meters tall, perennial shrub with unbranched upright stem, with green blossoms july to October. The whole plant mainly the stems have hundreds of needle like stinging hairs that cause skin eruptions. Once dried or slightly cooked the entire nettle plant is edible.

This is a fully matured Stinging Nettle. This is a young Stinging Nettle plant.

---------------------------------------------------------------------------Bull Nettle

---------------------------------------------------------------------------Cnidoscolus stimulosus Euphorbiaceae family or (rubber family) also called Spurge Nettle, Horse Nettle and tread-softly. Grows in southeastern United States to south Florida and Texas from Virginia in sandy ground and waste areas. Growing up to 60 cm with white blossoms appearing from March to September. Covered with stinging hairs that cause skin eruptions.

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-----------------------------------------------------------------------------------------Wood Nettle

-----------------------------------------------------------------------------------------Laportea Canadensis Urticaceae family, also in the Nettle family growing in North America from Canada to Florida. Often found growing in low forests and riverbanks. This plant prefers rich ground full of nutrients. Growing about 1.1 meters tall, shrub with green blossoms, flowering June to September. All above ground parts have stinging hairs that cause skin eruptions. Much like stinging nettle beside that the leaves are alternate. This Nettle is also edible once cooked or dried.

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-----------------------------------------------------------------------------Giant Hogweed

-----------------------------------------------------------------------------Heracleum mantegazzianum of the Carrot family also called Parsnip tree and Herkuleskraut. Giant Hogweed grows in north America used as a ornamental plant in some parks and gardens, growing in woodlands and waysides in the wild. Reaching 3-5 meters tall with leaves up to 1 meter long. White blossoms in clusters the stem is hollow with red speckles or dots blooming july to September.

Sap from the entire plant and mainly the stem is a phototoxic. After the sap gets on the skin and is exposed to sunlight, the next day the skin reddens and blisters the next day if not aided. Giant Hogweed is related closely to Cows parsnip and

Heracleum mantegazzianum  Somm.&Lev.

Giant Hogweed

  Apiaceae (Umbelliferae) family (Carrot family)

Synony

Description: Perennial shrub, 3 to 5 m high, leaves up to 1 m long. White blossoms in clusters up to 50 cm in diameter. Stem hollow, with red speckles, up to 10 cm in diameter. Period of bloom from July to September.

Effects: Sap from all parts of the plant, particularly from the stem, acts as a phototoxic. When the juice gets on the skin and the skin is then exposed to ultraviolet light (some hours in the sun may be enough), the skin reddens next day, after another day a strong blistering can occur. The skin changes resemble second-degree burns. Often scars or pigment changes remain permanently or last for years. Also poisonous when ingested.

Measures: Avoid either the plant's sap or the sunlight. The sap can be washed away with water and soap. Corticosteroid ointment. See a doctor if necessary.

Reference: Benezra; Roth; "Der Spiegel" Nr. 33/1989; "JAMA" Dec 12/1980 Vol 244 No 23

Similar plants: Heracleum sphondylium (Cow Parsnip) is similar in appearance and effect, only up to 1.50 m in size, widespread in Europe. Similar plants include other Heracleum species as well as

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Pastinaca sativa and Angelica archangelica (also beloning to the Apiaceae family).

cow parsnip

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Water hemlock or spotted cowbane Cicuta maculata Parsley (Apiaceae) Family

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Description: This perennial herb may grow to 1.8 meters high. The stem is hollow and sectioned off like bamboo. It may or may not be purple or red striped or mottled. Its flowers are small, white, and grow in groups that tend to form flat umbels. Its roots may have hollow air chambers and, when cut, may produce drops of yellow oil.

Metopium toxiferum  Krug.

Black Poison Wood

  Anacardiaceae family (Sumac family)

Synonyms: Poison Bark (en), Doctor's Gum (en)

Occurrence: West-Indies, Bahamas, Southern Florida, Yucatan, Belize, Cuba, Jamaica. Frequently found in open areas.

Description: Shrub or small tree up to 12 m tall, bark yellowish-brown, wide open branches. The 3- to 7-fold leaves are light green and up to 30 cm long, shiny on top and dull underneath. Blossoms white, berries yellow to orange. The latex sometimes emerges by itself from bark and leaves and becomes black when exposed to air.

Effects: Chemically skin-irritating and allergizing. After contact with the latex 70% of the Europeans develop itching papules a few days later which develop into blisters and remain for several weeks. The smoke of the burning wood is also skin-irritating.

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Toxicodendron spp. 

Toxicodendron Species in General

  Anacardiaceae family (Sumac family)

Effects: Allergizing through urushiol in the resin of the plants. Through small injuries of the plant the resin can escape in low amounts from the leaf surface and from there get on the skin of a person who touches the leaf. Such small amounts can be already enough to induce an allergy. The allergen penetrates through the unhurt skin into the human body. However, the first contact remains mostly without any reaction. Subsequent contacts with a plant with any parts of the skin can induce rashes which appear right there and at the parts of the skin affected in earlier contacts. 24 to 48 hours after contact, itching, reddening, swelling, and wetting blisters use to appear. Against common opinion the liquid contained in the blisters is not an allergen and can transfer the rashes not to other people. However, this can happen by resin that remained on the skin.

The symptoms reach their climax approximately during the fifth day, then they heal without treatment in 1 to 2 weeks without leaving scars. However, secondary infections are possible if the blisters are not kept sterile. Abscesses or fever may occur then and scars can remain. If the poison gets into the eyes, severe inflammations and temporary or remaining cornea turbidity can follow. The allergy induced by the first contact usually lasts many years.

50% of the Americans react to slight contacts. Only 30% do not react at all. The poison is present in the plants also in winter, and also in dead and decaying plants. Smoke particles of burning parts of the plant spread the poison and can affect the skin and the respiratory tract. The allergen is spread easily, for example by shaking hands or via the fur of straying pets. The urushiol remains active outside the plant during at least 1 year and is not soluble in water. It is soluble in soap solution, though.

Measures: Thorough washing of the skin with water and soap as soon as possible after contact with the plant. If the skin is being washed within few hours this will likely prevent the reaction. Alcohol is unsuitable for cleaning because it accelerates the penetration of the poison into the skin. If no soap is available, the sap of Impatiens plants may also help. Rinsing the skin in flowing water is better than doing nothing at all. Rashes can be alleviated with corticosteroid ointment, while severe reaction needs medical attention. With very

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sensitive people it may be necessary to prevent allergic reactions with corticosteroids taken orally within 24 hours after contact. If one wants to remove Toxicodendron plants from a garden, they must be dug out with all roots.

Skunkbush Sumacs are found in canyons, chaparral areas, and oak-juniper woodlands near Tucson. These shrubs look very similar to the related Poison Ivy or Poison Oak (Toxicodendron species), as they all have compound, green leaves with 3 leaflets. Poison Ivy and Poison Oak can cause contact dermatitis (skin rash, blisters, and severe itching) if touched by persons who are or have become sensitive (allergic) to the substance urushiol present in the sap of these plants. Most people will get a rash if they touch Poison Ivy or Poison Oak.

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Skunkbush Sumac does not generally cause contact dermatitis, although

Poison hemlock, fool's parsley

Conium maculatum Parsley (Apiaceae) Family

Description: This biennial herb may grow to 2.5 meters high. The smooth, hollow stem may or may not be purple or red striped or mottled. Its white flowers are small and grow in small groups that tend to form flat umbels. Its long, turniplike taproot is solid.

CAUTION

This plant is very poisonous and even a very small amount may cause death. This plant is easy to confuse with wild carrot or Queen Anne's lace, especially in its first stage of growth. Wild carrot or Queen Anne's lace has hairy leaves and stems and smells like carrot. Poison hemlock does not.

Habitat and Distribution: Poison hemlock grows in wet or moist ground like swamps, wet meadows, stream banks, and ditches. Native to Eurasia, it has been introduced to the United States and Canada.

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