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(Cockscomb family)


This family of about 850 species in 65 genera is widely distributed in temperate and tropical regions. Many are intimately associated with man as pot herbs, as sources of edible seed, and as troublesome weeds. Some are cultivated for their attractive flowers.

Certain members of this family are capable of causing mechanical injury, others may induce contact sensitivity. Phototoxicity following ingestion has also been reported.

Achyranthes L.
[syn. Cyathula Lour.]

This tropical and sub-tropical genus may consist of only 3–5 very variable species which have hitherto been considered to be up to 100 distinct species.

Standley (1937b) noted that the sharp bracts penetrate the flesh easily, as do the hooked bristles on the flowers.

Achyranthes aspera L.
[syns Achyranthes indica Mill., Achyranthes robusta C.H.Wright, Centrostachys aspera Standley, Centrostachys indica Standley]
Burweed, Devil's Horsewhip, Mozotillo, Prickly Chaff-Flower

According to Rao (1981), the roots of this species are powdered, mixed with crushed snails, and applied by the Khasi and Garo tribes of Meghalaya, India to cure leprosy. A decoction of the roots has also been used with some success in the oral treatment of leprosy (Wade 1977).

Achyranthes fauriei Léveillé & Vaniot

This species possesses sharp spines at the bases of the utricles (Kariyone 1971) and is thus a possible source of mechanical injury.

Alternanthera pungens Kunth
[syns Alternanthera echinata Smith, Achyranthes repens L.]

Gardner & Bennetts (1956) include Alternanthera echinata in a list of plants known or suspected of causing dermatitis.

Amaranthus L.

The pollen of some species, particularly Amaranthus retroflexus L., the pigweed, which is a common weed of cultivated ground in the USA, can cause pollinosis (Wodehouse 1971).

The common name pigweed is also applied to species of Chenopodium L. (fam. Chenopodiaceae) which co-occur as weeds with Amaranthus retroflexus, and also flower at about the same time (King 1966). Thus a report (Anneberg 1938) of keratitis attributable to entry into farmers' eyes of the pollen of "pigweed-red root" may have referred to the pollen of species in either or both genera.

Amaranthus blitoides S.Watson
Mat Amaranth, Prostrate Amaranth, Prostate Pigweed, Spreading Pigweed

This species produced positive patch test reactions in one of 50 patients who had "weed dermatitis" (Shelmire 1939a).

Amaranthus hypochondriacus L.
[syns Amaranthus bernhardii Moq., Amaranthus frumentaceus Buch.-Ham. ex Roxb., Amaranthus leucocarpus S.Watson, etc.]
Amaranth, Golden Amaranth, Love-Lies-bleeding, Prince's Feather, Prince-of-Wales Feather, Red Cockscomb, Trauer-Fuchsschwanz

According to Wren (1975) and Stuart (1979), a decoction of this plant may be used as an application in ulcerated conditions of the throat and mouth, and used as a wash for ulcers and sores.

Amaranthus retroflexus L.
Careless Weed, Redroot Amaranth, Redroot Pigweed, Rough Pigweed

This species produced positive patch test reactions in one of 50 patients who had "weed dermatitis" (Shelmire 1939).

Amaranthus spinosus L.
Thorny Pigweed, Spiny Amaranth

The plant bears stiff, sharp spines in the leaf axils (Standley 1937). The plant sometimes produces mechanical injuries (Pammel 1911).

Amaranthus tricolor L.
[syns Amaranthus gangeticus L., Amaranthus mangostanus L.]

Ingestion of Amaranthus mangostanus as a famine food has been reported to cause atriplicism, a syndrome presenting as a severe photodermatitis that may be accompanied by systemic symptoms (Cairns et al. 1968).

Amaranthus tuberculatus J.D.Sauer
[syns Acnida tamariscina auct., Amaranthus tamariscinus auct.]
Roughfruit Amaranth, Western Water Hemp

The statement that contact sensitivity to Acnida tamariscina may occur in farmers (Waldbott 1953) appears to lack confirmation (Shelmire 1939a).

Amaranthus viridis L.

Patch tests carried out using the leaves of this species crushed in a small quantity of normal saline elicited positive reactions in 4 of 40 contact dermatitis patients tested in New Delhi, India (Singh et al. 1978).

Quisumbing (1951) reports the use of this species as a sternutatory.

Centrostachys Wall.

Oakes & Butcher (1962) list Centrostachys as being capable of causing mechanical injury. According to Mabberley (2008), this genus is monotypic. The type species is Centrostachys aquatica Wall. The plant to which Oakes & Butcher were referring might have been a species of Achyranthes L., the genus to which many Centrostachys species have been moved.

[Further information available but not yet included in database]

Deeringia amaranthoides Merr.
[syns Achyranthes amaranthoides Lam., Digera arvensis Forssk.]

The powdered root of this species may cause violent sneezing (Burkill 1935).

Froelichia floridana Moq.
Cottonweed, Prairie Froelichia

This species is listed by Shelmire (1940) as an infrequent sensitiser, but no clinical details are given.

Pandiaka metallorum Duvign. & Bockstal

This southern African species is known to hyperaccumulate copper and cobalt when growing in soils rich in these elements. Levels of up to 6000 µg/g (ppm) of copper and 570 ppm of cobalt have been recorded from dried plant material originating from Zaïre (Malaisse et al. 1979). The contact sensitising capacity of cobalt and its salts is well documented (Malten et al. 1976, Cronin 1980). Copper is only a rare sensitiser (Karlberg 1983).


The khaki weed, Alternanthera repens [probably Alternanthera pungens Kunth, syn. Alternanthera repens Kuntze] has been suspected of causing dermatitis in cattle (Webb 1948a).

Cattle and horses have been poisoned by eating Amaranthus species, possibly because of their high content of potassium nitrate (Muenscher 1951, Kingsbury 1964). Photosensitivity seems not to be a feature of this syndrome.


  • Anneberg AR (1938) Corneal reaction to weed pollen. American Journal of Ophthalmology 21: 1265.
  • Burkill IH (1935) A Dictionary of the Economic Products of the Malay Peninsula, Vols 1 & 2. London: Crown Agents [doi] [WorldCat] [url] [url-2]
  • Cairns RJ, Champion RH, Wilkinson DS (1968) Cutaneous reactions to physical agents. In: Rook AJ, Wilkinson DS, Ebling FJG (Eds) Textbook of Dermatology. 1st edn, Vol. 1, pp. 323-361. Oxford: Blackwell Scientific Publications
  • Cronin E (1980) Contact Dermatitis. Edinburgh: Churchill Livingstone [WorldCat]
  • Gardner CA, Bennetts HW (1956) The Toxic Plants of Western Australia. Perth: West Australian Newspapers [doi] [WorldCat] [url] [url-2]
  • Kariyone T (1971) Atlas of Medicinal Plants. Osaka, Japan: Takeda Chemical Industries.
  • Karlberg A-T, Boman A, Wahlberg JE (1983) Copper — a rare sensitizer. Contact Dermatitis 9(2): 134-139 [doi] [url] [url-2] [pmid]
  • King LJ (1966) Weeds of the World. Biology and control. London: Leonard Hill.
  • Kingsbury JM (1964) Poisonous Plants of the United States and Canada. Englewood Cliffs, New Jersey: Prentice Hall.
  • Mabberley DJ (2008) Mabberley's Plant-Book. A portable dictionary of plants, their classification and uses, 3rd edn. Cambridge: Cambridge University Press [WorldCat]
  • Malaisse F, Grégoire J, Morrison RS, Brooks RR and Reeves RD (1979) Copper and cobalt in vegetation of Fungurume, Shaba Province, Zaïre. Oikos 33(3): 472-478.
  • Malten KE, Nater JP, van Ketel WG (1976) Patch Testing Guidelines. Nijmegen: Dekker & van de Vegt [WorldCat]
  • Muenscher WCL (1951) Poisonous Plants of the United States, 2nd edn. New York: Macmillan Company [WorldCat]
  • Oakes AJ, Butcher JO (1962) Poisonous and Injurious Plants of the U.S. Virgin Islands. Miscellaneous Publication No. 882. Washington, DC: Agricultural Research Service, United States Department of Agriculture [WorldCat] [url] [url-2]
  • 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]
  • Quisumbing E (1951) Medicinal Plants of the Philippines. Technical Bulletin 16, Philippines Department of Agriculture and Natural Resources. Manila, Philippine Islands: Manila Bureau of Printing [WorldCat] [url]
  • Rao RR (1981) Ethnobotany of Meghalaya: medicinal plants used by Khasi and Garo tribes. Economic Botany 35(1): 4-9 [doi] [url] [url-2]
  • Shelmire B (1939a) Contact dermatitis from weeds: patch testing with their oleoresins. Journal of the American Medical Association 113(12): 1085-1090 (and unpublished table of results accompanying reprints) [doi] [url]
  • Shelmire B (1940) Contact dermatitis from vegetation. Southern Medical Journal 33: 338.
  • Singh R, Siddiqui MA, Baruah MC (1978) Plant dermatitis in Delhi. Indian Journal of Medical Research 68(Oct): 650-655 [url] [pmid]
  • Standley PC (1937b) Flora of Costa Rica, Part II. Publications of the Field Museum of Natural History, Botanical Series 18: 398-780+ix [url] [url-2]
  • Stuart M (1979) Reference section. In: Stuart M (Ed.) The Encyclopedia of Herbs and Herbalism, pp. 141-283. London: Orbis Publishing [WorldCat] [url]
  • Wade A (Ed.) (1977) Martindale. The Extra Pharmacopoeia. 27th edn. London: Pharmaceutical Press [WorldCat]
  • Waldbott GL (1953) Contact Dermatitis. Springfield, Ill.: Charles C Thomas.
  • Webb LJ (1948a) Guide to Medicinal and Poisonous Plants of Queensland. Bulletin No. 232. Melbourne, Victoria: Council for Scientific and Industrial Research [doi] [url]
  • Wodehouse RP (1971) Hayfever Plants, 2nd revised edn. New York: Hafner Publishing Co.
  • 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

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