[BoDD logo]


Google uses cookies
to display context-
sensitive ads on this
page. Learn how to
manage Google cookies
by visiting the

Google Technologies Centre

 ▼ ▼ ▼ ▼ ▼ ▼ ▼


 ▲ ▲ ▲ ▲ ▲ ▲ ▲

[BBEdit logo]




(Dock family)


800 species in 40 genera are chiefly found in north temperate regions, a few in tropical, arctic and southern regions. The fruits of some species possess hooks.

[Summary yet to be added]

Coccoloba rheifolia

The wood is said to be capable of producing dermatitis (Orsler 1973).

Coccoloba laurifolia


Coccoloba utifera
Sea Grape

Twenty workmen in Strasbourg were said to have irritation of the eyes and nose after working with coccoloba in 1904. As investigations into the cause were unsuccessful, nothing was published at the time but Czimatis and Hagemann (1910) refer to the incident. Hausen (1970) who elucidated this, noted that he had heard of irritation by the wood in Guadeloupe but found no case-reports. He found several alkaloids in the wood. According to Woods and Calnan (1976) the strong sensitiser cocobolo was not finally identified as Dalbergia spp. till 1918, and was long confused with similarly named woods such as Coccoloba, Cocos and cocus (Wiesner 1903). Cocobolo seems the likeliest cause of the Strasbourg outbreak, as Coccoloba has never been much exported (Boulger 1908, Record & Hess 1943).


Two species are found in the Mediterranean region, southern Africa and Australia.

Emex australis Steinh.
Double Gee, Spiny Emex, Southern Threecornerjack, Three-cornered Jack

The hard fruit bear three rigid spreading spines which can cause injuries to humans and livestock (Aplin 1976).

Eriogonum umbellatum Torr. var. ellipticum Reveal
[syns Eriogonum stellatum Benth., Eriogonum umbellatum Torr. var. croceum S. Stokes ex R.J. Davis, Eriogonum umbellatum Torr. var. stellatum M.E.Jones]
Sulfur-Flowered Buckwheat

[Information available but not yet included in database]


Fifteen species are found in temperate Eurasia.

Fagopyrum esculentum Moench
[syns Fagopyrum fagopyrum H.Karst., Fagopyrum sagittatum Gilib., Polygonum fagopyrum L., Polygonum cereale Salisb.]

This species is widely cultivated especially in North America. The plant is used for green fodder and provides good honey. The seeds are used to make flour.

All parts of the plant, whether fresh or dry, are capable of producing photosensitisation if ingested, the fresh plant in the flowering stage being most toxic. Animals that are stabled do not develop symptoms of photosensitisation when fed on buckwheat. On exposure to sunlight there is inflammatory swelling (dermatitis erythematosa) of the ears, face, and eyelids accompanied by severe itching. In severe cases, vesicles appear. In very severe cases, the vesicular stage may develop into a necrotic dermatitis. Symptoms of photosensitisation may appear in less than 20 hours after commencement of feeding. The disease is known as fagopyrism (Steyn 1934). Pigments with an absorption band at about 590 nm are responsible for photosensitisation (Watt & Breyer-Brandwijk 1962, Kingsbury 1964). Fagopyrin and related fluorescent chemicals are related to those of Hypericum (Bigger 1959). Photosensitivity has been reported to occur in humans who ingest buckwheat (Pammel 1911, Bruce 1927, Sheard et al. 1928, Steyn 1934, Mathews 1937, Muenscher 1951, Behl et al. 1966).

Buckwheat has been reported to cause contact irritation of the skin (Watt & Breyer-Brandwijk 1962, Muenscher 1951). It can also produce Type I hypersensitivity reactions (Blumstein 1935). According to Blumstein (1935) and Blum (1941) most, if not all, cases of buckwheat poisoning in man are not examples of photosensitisation but are allergic reactions. Hjorth (1968) recorded one positive patch test reaction to the plant and negative reactions in five cases.

Using the method of Daniels (1965), the seeds of F. esculentum, both with the husk on and dehusked, did not produce psoralen-type phototoxicity for Candida albicans (Mitchell JC 1972 — unpublished observation). Fagopyrism has also been attributed to ingestion of Polygonum (Mathews 1937).

Use of the straw as a head rest caused asthma and rhinitis (Matsumura et al. 1964).

Fagopyrum tataricum Gaertn.
[syn. Polygonum tataricum L.]
Green Buckwheat

Ingestion of the plant has been reported to produce a photosensitivity syndrome resembling fagopyrism in animals (Steyn 1934, Mathews 1937).

Fallopia convolvulus Á.Löve
[syn. Bilderdykia convolvulus Dumort., Fagopyrum convolvulus Gross, Polygonum convolvulus L.]
Black Bindweed, Windenknöterich

Mechanical injury can occur from ingestion of the hard, trigonous, pointed fruits (Long 1924). A patient who reacted strongly when patch tested with the leaves and flowers of Polygonum nodosum (now named Persicaria lapathifolia – see below) failed to react to Polygonum convolvulus and to four other members of the Polygonaceae (Möslein 1963).


30 species are found in tropical and southern Africa.

Oxygonum atriplicifolium

The three spined fruits stick to the feet when walking (Williamson 1955).

Persicaria lapathifolia Delarbre
[syns Polygonum lapathifolium L., Polygonum nodosum Pers.]
Pale Knotweed, Pale Persicaria

Möslein (1963), referring to Polygonum nodosum, observed positive patch test reactions to the flowers and the leaf in one patient who had contact dermatitis. Negative patch test reactions were observed in four control subjects. Negative patch test reactions were also observed to Polygonum aviculare L., Polygonum bistorta L., Polygonum persicaria L., Polygonum viviparum L., and to Polygonum convolvulus L.

Ingestion of the plant is considered to cause dermatitis in cattle at some times (Hurst 1942).

Polygonum acre

The juice of the plant is acrid (White 1887) and irritant (Pammel 1911).

Polygonum aviculare L.
Wire Weed, Knot Grass, Bird Knotgrass, Dooryard Knotweed

The plant is used to make a tea ("Weidermannscher tea" or" Homeriana tea") and contains tannic acid and a trace of volatile oil. The plant is used for topical application as an astringent and styptic and has been reported to cause contact dermatitis in horses and sheep due to the presence of an acid or "smarting" substance which may be salicic acid (Watt & Breyer-Brandwijk 1962).

According to Muenscher (1951), contact with the plant has caused contact dermatitis in "susceptible" individuals. Gardner & Bennetts (1956) included this species in a list of plants known or suspected of causing dermatitis. The plant was not irritant by patch test in one patient (Möslein 1963). A gardener developed dermatitis of the opposing surfaces of the right forefinger and thumb and of the intervening finger web. Two days previously he had pulled P. aviculare which was a prevalent weed. He applied an ointment to his finger and thumb. Five months later, he developed dermatitis of the forearm and trunk. This dermatitis was attributed to a re-use of the ointment at these sites. The juice of the plant was considered to have contaminated the ointment. Patch tests were not recorded (Lloyd 1914).

Ingestion of the plant was said to produce dermatitis in animals (Gates 1930, Sampson and Malmsten 1935).

Polygonum barbatum

The juice of the plant is acrid. The root is astringent and the sap is applied to wounds as an "antiseptic" (Watt & Breyer-Brandwijk 1962).

Polygonum bistorta L.
Bistort, Snakeweed, Adderwort, English Serpentary, Dragonwort

Stuart (1979) notes that the powdered rhizome acts as a styptic, and that preparations of the root have been used in folk medicine as external applications to cuts, sores, and haemorrhoids, these styptic and vulnerary properties being attributable to the astringent tannins present in the rhizome.

Polygonum cuspibatum

This perennial species, which has become popular in Danish gardens, caused a typical streaky plant dermatitis of the arms in a gardener. Patch test to the plant produced a strong vesicular reaction; one of ten controls also had a positive reaction (Hjorth and Mitchell 1973). Although patch tests to the leaves could produce an irritant reaction, the history and clinical findings left no doubt of an allergic contact dermatitis.

Polygonum flaccidum

This species has irritant properties (Pammel 1911).

Polygonum bistorta L.
Bistort, Snake Root

The plant was not irritant by patch test in one patient (Möslein 1963).

Polygonum hydropiper L.
Smartweed, Water Pepper

The plant irritates the hands and face of persons who collect it, producing burning and itching (White 1887). Some colloquial names for this plant indicate an awareness of its properties viz. biting persicaria, bity tongue, pepper plant, red knees (Grieve 1931). The acrid juice is irritant and the bruised leaves and the seeds, when employed as a poultice, blister the skin (Behl et al. 1966). Other authors (MacDougal 1894, Coulter 1904, Pammel 1911, Weber 1937, Muenscher 1951, Schwartz et al. 1957) who refer to the irritant properties of the plant for humans do not add any clinical details other than a note of irritation of the eyes and nostrils by the juice of the plant.

According to (Grieve 1931), a fomentation of the leaves is beneficial for chronic ulcers and haemorrhoids [the latter use probably accounting for the colloquial names smartass and arse-smart]. Grieve (1931) also records that smartweed was an old country remedy for curing proud flesh in the sores of animals; and that the bruised leaves were used as a poultice to whitlows.

Unfavourable effects from the plant have also been observed in animals. It is difficult to define whether contact dermatitis, dermatitis from ingestion or photosensitivity from ingestion actually occurred. Ingestion of the plant has been reported to produce a photosensitivity syndrome resembling fagopyrism in animals (Steyn 1934). In 1931, this species was present in pastures in New South Wales in which a number of cows developed dermatitis (Hurst 1942).

This plant and other species of Polygonum contain acrid smarting substances which may cause dermatitis in stock if ingested (Gates 1930). The juice is acrid, causing irritation and smarting, especially when in contact with the eyes and nostrils of animals and is possibly a cause of dermatitis (Long 1924).

Polygonum hydropiperoides

This species is irritant (Pammel 1911).

Polygonum minus
Slender Knotweed

This species is stated to be free from the "biting taste" characteristic of many species of Polygonum; it was suspected of causing dermatitis in a cow in New South Wales (Hurst 1942).

Polygonum orientale

The plant has irritant properties (Pammel 1911). This species was considered on field evidence to have caused dermatitis of the udder and perineum of dairy cattle but on testing by external application to the skin of a steer and a calf, no observable ill effect was produced (Hurst 1942). White (1937) states that in Queensland, the loss of five young pigs was attributed to this plant and that the symptoms of poisoning were swelling of the ears, face and eyelids with considerable irritation of the affected parts. However, feeding experiments produced negative results (Hurst 1942).

Polygonum persicaria L.
Persicaria, Redleg

The plant has a very acrid juice which can cause smarting and irritation especially when in contact with the eyes and nostrils of animals (Pammel 1911, Gates 1930). The plant was not irritant by patch test in one patient (Möslein 1963). The plant can produce dermatitis in "susceptible" individuals (Muenscher 1951 Schwartz et al. 1957). Ingestion of the plant has been reported to produce a photosensitivity syndrome resembling fagopyrism in animals (Steyn 1934, Mathews 1937).

Polygonum prostratum R.Br.
Trailing Knotweed

The plant was suspected of causing necrotic dermatitis in animals in New South Wales (Hurst 1942). Gardner & Bennetts (1956) include this species in a list of plants known or suspected of causing dermatitis, probably from Hurst (1942).

Polygonum punctatum
Smartweed, Poor Man's Pepper, Water Pepper

The colloquial names of this species suggest an irritant effect. The leaves of the plant, which is common in damp places in Britain, have rubefacient properties (Prosser White 1934). The plant is listed as irritant (Weber 1937). The juice of the plant has irritant properties (Coulter 1904). The crushed leaves and stems are irritant (Allen 1943).

Polygonum pulchrum

The rhizome of this species contains an acrid resin (Watt & Breyer-Brandwijk 1962).

Polygonum salicifolium

A paste made of the leaves is applied to sores by the Zulus (Watt & Breyer-Brandwijk 1962).

Polygonum viviparum L.
Viviparous Bistort

The plant was not irritant by patch test in one patient (Möslein 1963). The fleshy root stock can be cooked and eaten as a substitute for nuts and raisins because of its almond flavour (Szczawinski and Hardy 1972).

Rheum L.

50 species are found in temperate and subtropical Asia.

Rheum officinale Baill.

This plant which furnishes medicinal rhubarb is listed as irritant (Schwartz et al. 1957). Chrysophanic acid an irritant of Andira is derived from the plant.

Rheum palmatum L.

This species furnishes medicinal rhubarb. Chrysophanic acid is derived from this plant and from Rumex, senna (Cassia), cascara sagrada (Rhamnus). Related compounds are derived from Andira.

Rheum rhaponticum L.

The leaf stalk furnishes the vegetable, rhubarb. The leaf blade can cause dermatitis possibly from a content of oxalic acid and oxalates (Muenscher 1951, McCord 1962). Anaphylaxis from ingestion of rhubarb was reported by Delcourt (1924).

Rumex L.

About 200 species are recognised, of cosmopolitan distribution especially in north temperate regions. Some species yield chrysophanic and oxalic acids.

Oxalic acid is a strong local irritant and caustic. The chemical causes gangrenous ulcerations. The nails turn blue, become brittle and may fall off leaving an ulcerated nail bed (Greenberg and Lester 1954).

Oxalic acid is considered to be a known allergen and is therefore removed from certain brand name cosmetics (Anon 1973).

Rumex acetosa L.
Sour Dock, Sorrel

Ingestion of the plant produces burning in the mouth and poisoning (Watt & Breyer-Brandwijk 1962). When eaten as pot-herbs or greens, the plant can produce dermatitis in "susceptible" individuals (Allen 1943, Muenscher 1951, Behl et al. 1966).

Rumex acetosella L.
Sheep's Sorrel, Field Sorrel

Ingestion of the plant produces burning in the mouth and poisoning (Watt & Breyer-Brandwijk 1962). When eaten as a pot-herbs or greens, the plant can produce dermatitis in "susceptible" individuals (Allen 1943, Muenscher 1951, Behl et al. 1966).

The acrid smarting juice is thought to be a cause of dermatitis in horses and sheep (Gates 1930). Subsequent references to contact dermatitis caused by this plant (Allen 1943, Schwartz et al. 1957, Gardner & Bennetts 1956, Behl et al. 1966) are probably derived from Gates (1930).

Rumex aquaticus L.
Water Dock, Bloodwort

Wren (1975) notes that the root has been used in folk medicine for cleansing ulcers in affections of the mouth.

Rumex crispus L.
[syn. Lapathum crispum Scop.]
Curled Dock, Sour Dock, Yellow Dock

According to Wren (1975), a preparation of the root may be used as a traditional remedy for [unspecified] skin diseases and for haemorrhoids. Stuart (1979) notes that it is of value both internally and externally for skin complaints including ringworm, scabies, and urticaria.

In an investigation of "weed dermatitis" an extract of the plant produced negative patch test reactions in all of 50 patients tested (Shelmire 1939). However, both Muenscher (1951) and Stuart (1979) assert that the plant may produce dermatitis.

The plant contains oxalic acid, oxalates, chrysophanic acid, emodin, tannin and other chemicals (Watt & Breyer-Brandwijk 1962). Dermatitis attributed to the plant is said to be from a content of rumicin which can have rubefacient properties (Watt & Breyer-Brandwijk 1962). Rumicin is a name for chrysophanic acid. The effects of chrysophanic acid and its derivatives are noted under Andira.

Horses and sheep that ingest the plant in large quantities can develop dermatitis (Gates 1930, Hurst 1942, Watt & Breyer-Brandwijk 1962).

Rumex nepalensis

The root is used as an astringent and for dyeing from its content of tannin (Watt & Breyer-Brandwijk 1962).

Rumex obtusifolius

This species which yields chrysophanic acid has been used in herbal medicine for skin diseases (Watt & Breyer-Brandwijk 1962).

Rumex vesicarius L.

Behl & Captain (1979) noted that in India, rubbing with the crushed leaves of this species or of Rumex maritimus L. (or with saliva or dilute ammonia) is recommended as a popular remedy for nettle stings (Urtica L. spp., fam. Urticaceae).

Triplaris schomburgkii


Triplaris surinamensis

These trees found along the Amazon have slender elongated tubular branches in which stinging ants make their nest. Incautious travellers leaning against these trees are liable to be stung (Menninger 1967).


  • Allen PH (1943) Poisonous and injurious plants of Panama. American Journal of Tropical Medicine 23(Suppl): 3-76 [doi] [url] [url-2]
  • Anon (1973) Almay Hypo-Allergenic Cosmetics Product Formulary, 8th edn: Schieffelin and Co., Pharmaceutical Laboratories Division, 562-5th Ave., New York, N.Y. 10036
  • Aplin TEH (1976) Poisonous garden plants and other plants harmful to man in Australia. Western Australian Department of Agriculture. Bulletin 3964 [url] [url-2]
  • Baggers, J.D. (1959) Photodynamic compounds in plants. In: The Pharmacology of Plant Phenolics. ed. Fairbairn, J.W. London. Academic Press. p. 71-79.
  • Behl PN, Captain RM, Bedi BMS, Gupta S (1966) Skin-Irritant and Sensitizing Plants Found in India. New Delhi: PN Behl [WorldCat]
  • Blum HF (1941) Photodynamic Action and Diseases Caused by Light. New York: Reinhold Publishing Corp.
  • Blumstein, G.L. (1935) Buckwheat sensitivity. J. Allergy 7: 74.
  • Boulger, G.S. (1906/7) Familiar Trees. London. Cassele.
  • Bruce, E.A. (1927) Astragalus campestris and other stock-poisoning plants of British Columbia. Dominion of Canada Dept. Agr. Bull. 88.
  • Coulter S (1904, published 1905) The poisonous plants of Indiana. Proceedings of the Indiana Academy of Science: 51-63 [url] [url-2]
  • Czimatis and Hagemann (1910) Ueber Erkrankungen durch Holzstaub. Hygienische Rundschau 20: 761.
  • Daniels, F. (1965) A simple microbiological method for demonstrating phototoxic compounds. J. Invest. Derm. 44: 259.
  • Delcourt (1924) Un cas d'anaphylaxie pour la rhubarb. Le Scalpel 77: 594.
  • Gardner CA, Bennetts HW (1956) The Toxic Plants of Western Australia. Perth: West Australian Newspapers [doi] [WorldCat] [url] [url-2]
  • Gates FC (1930) Principal poisonous plants in Kansas. Agricultural Experiment Station, Kansas State Agricultural College, Technical Bulletin 25: 1-67 [url]
  • Greenberg LA, Lester D (1954) Handbook of Cosmetic Materials. Their properties, uses, and toxic and dermatologic actions. With a bibliography of over 2,500 titles. New York: Interscience Publishers [doi] [WorldCat] [url] [url-2]
  • Grieve M (1931) A Modern Herbal. The medicinal, culinary, cosmetic and economic properties, cultivation and folk-lore of herbs, grasses, fungi, shrubs & trees with all their modern scientific uses, 1 & 2. London: Jonathan Cape [WorldCat] [url]
  • Hausen B.M. (1970) Untersuchungen uber Gesundheitsschadigende Holzer. Thesis, Hamburg.
  • Hjorth, N. (1968) at Finsen Institute. Personal Communication to JC Mitchell.
  • Hjorth, N. and Mitchell, J.C. (1973) Polygonum dermatitis. Contact Dermatitis Newsletter (15): 426.
  • Hurst E (1942) The Poison Plants of New South Wales. Sydney: NSW Poison Plants Committee [WorldCat] [url]
  • Kingsbury, J.M. (1964) Poisonous Plants of the United States and Canada. Englewood Cliffs, New Jersey. Prentice-Hall Inc.
  • Lamson, R.W. (1924) Sudden death associated with the injection of foreign substance. J. Am. Med. Ass. 82: 1091.
  • Lloyd, G.W. (1914) Dermatitis venenata. Br. Med. J. 2: 837.
  • Long, H.C. (1924) Plants Poisonous to Livestock. 2nd edn. Cambridge University Press.
  • Mathews, F.P. (1937) Photosensitization and the photodynamic diseases of man and the lower animals. Arch. Path. 23: 399.
  • MacDougal, D.T. (1894) Poisonous influences of various species of cyptipedium. Minesota Botan. Studies pp. 32 and 450.
  • Matsumura, T., Tateno, K., Yugami, S. et al. (1964) Six cases of buckwheat asthma induced by buckwheat flour attached to buckwheat chaff in pillows. J. Asthma Res. 1: 219.
  • McCord CP (1962) The occupational toxicity of cultivated flowers. Industrial Medicine and Surgery 31(8): 365-368
  • Menninger EA (1967) Fantastic Trees. New York: Viking Press [WorldCat] [url]
  • Möslein P (1963) Pflanzen als Kontakt-Allergene. [Plants as contact allergens]. Berufsdermatosen 11(1): 24-32 [url]
  • Muenscher WCL (1951) Poisonous Plants of the United States, 2nd edn. New York: Macmillan Company [WorldCat]
  • Orsler R.J. (1972) Personal communication from Forest Products Research Laboratory, Princes Risborough, Bucks, England.
  • Pammel LH (1911) A Manual of Poisonous Plants. Chiefly of North America, with Brief Notes on Economic and Medicinal Plants, and Numerous Illustrations. Cedar Rapids, IA: Torch Press [WorldCat] [url] [url-2]
  • Prosser White R (1934) The Dermatergoses or Occupational Affections of the Skin, 4th edn. London: HK Lewis [doi] [WorldCat] [url] [url-2]
  • Record SJ, Hess RW (1943) Timbers of the New World. New Haven: Yale University Press [doi] [WorldCat] [url]
  • Sampson, A.W. and Malmsten, H.E. (1935) Stock poisoning plants of California. Univ. California, Coll. Agr. Expt. Stat. Bull. 593.
  • Schwartz L, Tulipan L, Birmingham DJ (1957) Irritant plants and woods. In: Occupational Diseases of the Skin. 3rd edn, pp. 636-672. London: Henry Kimpton [doi] [WorldCat] [url] [url-2]
  • Shelmire, B. (1939) Contact dermatitis from weeds; patch testing with their oleoresins. J. Am. Med. Ass. 113: 1085.
  • Sheard, C., Caylor, H. and Schlotthauer, C. (1928) Photosensitization of animals after ingestion of buckwheat. J. Exp. Med. 47: 1013.
  • Steyn DG (1934) The Toxicology of Plants in South Africa together with a consideration of poisonous foodstuffs and fungi. South Africa: Central News Agency
  • Stuart M (1979) Reference section. In: Stuart M (Ed.) The Encyclopedia of Herbs and Herbalism, pp. 141-283. London: Orbis Publishing [WorldCat] [url]
  • Szczawinski, A.F. and Hardy, G. A. (1972) Guide to Common Edible Plants of British Columbia. Handbook No. 20. Dept. of Recreations and Conservation. Government of British Columbia, Victoria, B.C.
  • Watt JM, Breyer-Brandwijk MG (1962) The Medicinal and Poisonous Plants of Southern and Eastern Africa. Being an account of their medicinal and other uses, chemical composition, pharmacological effects and toxicology in man and animal, 2nd edn. Edinburgh: E & S Livingstone [doi] [WorldCat] [url] [url-2]
  • Weber LF (1937) External causes of dermatitis. A list of irritants. Archives of Dermatology and Syphilology 35(1): 129-179 [doi] [url]
  • White, C.T. (1937) Ann. Report Govt. Botanist, Queensland.
  • White JC (1887) Dermatitis Venenata: an account of the action of external irritants upon the skin. Boston: Cupples and Hurd [doi] [WorldCat] [url] [url-2]
  • Wiesner, J. (1903) Die Rohstoffe des Pflanzenreiches. 2nd edn. Leipzig, Engelmann.
  • Williamson J (1955) Useful Plants of Nyasaland. (Edited by Greenway PJ). Zomba, Nyasaland: Government Printer [WorldCat] [url] [url-2]
  • Woods B, Calnan CD (1976) Toxic woods. British Journal of Dermatology 95(Suppl 13): 1-97 [doi] [url] [url-2] [pmid]
  • Wren RC (1975) Potter's New Cyclopaedia of Botanical Drugs and Preparations. (Re-edited and enlarged by Wren RW). Bradford, Devon: Health Science Press [WorldCat] [doi] [url] [url-2]

Richard J. Schmidt

[Valid HTML 4.01!]

[2D-QR coded email address]
[2D-QR coded url]