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Acorus - Arisaema

(Arum family)


This large family contains about 2000 species in 115 genera. Although some species are natives of temperate regions, the vast majority are to be found in the tropics. They vary in habit from herbs large and small, to climbing shrubs and epiphytes, and include marsh plants and one floating water plant.

The cuckoo pint (Arum maculatum L.) is a common woodland plant in Britain and Europe. Other species of Arum L. are cultivated as house and greenhouse plants. Among the more popular of the tropical species grown as house plants and decorative objects in hotel lobbies and such places are species of Alocasia G.Don, Anthurium Schott, Arisaema Mart., Caladium Vent., Colocasia Schott, Monstera Schott, Philodendron Schott, and Zantedeschia Spreng..

Many plants in this family contain a poisonous watery juice which may be rendered non-toxic by heat. The rhizomes of many species contain a large quantity of starch and are used as food after suitable preparation. Colocasia esculenta Schott (syn. Colocasia antiquorum Schott), Cyrtosperma edule Schott (syn. Cyrtosperma merkusii Schott), as well as species of Alocasia, Arum, and Caladium are of value.

Many, but not all, species in this family contain bundles of minute needle-like crystals of calcium oxalate (known as raphides). They are responsible at least in part for the irritant properties of these plants when they are damaged and brought into contact with the skin or mucous membranes. The presence of other irritant compounds is also suspected - a proteinase has been demonstrated to occur in Dieffenbachia Schott species. Contact sensitivity to some of the species grown as house plants has also been recorded.

Acorus calamus L.
Sweet Flag

The rhizome of the sweet flag contains a pleasantly aromatic oil. The rhizome and its oil have been used in the indigenous medicine of many countries for millenia (Flückiger & Hanbury 1874), and were accepted in western medicine until recently when their use in foods and cosmetics was prohibited by the FDA following long term feeding studies in rats which demonstrated carcinogenicity (Opdyke 1977).

The aromatic oil may be extracted from the rhizomes by steam distillation, and is known as calamus oil. Bath preparations containing calamus oil have been reported to cause skin erythema; the oil has also been suspected of causing dermatitis in hypersensitive individuals (Klarmann 1958, Opdyke 1977). However, tests with undiluted calamus oil on the skin of mice, swine, rabbits, and guinea pigs did not demonstrate irritancy. A 48 hour closed patch test on human skin using 4% calamus oil in petrolatum similarly failed to demonstrate irritancy, and a maximisation test on 23 volunteers using this preparation failed to demonstrate a sensitising capacity. Phototoxicity following application of the undiluted oil to the skin of mice and swine was also not observed (Opdyke 1977).

Aglaonema Schott

About 50 species have been recorded from Indo-Malaysia. The caustic effect of the leaves of some species when used in folk medicine was recorded by Burkill (1935).

Aglaonema commutatum Schott
[syn. Scindapsus cuscuaria Presl]


Aglaonema modestum Schott

These plants contain minute needle-like crystals of calcium oxalate which are intensely irritating when brought into contact with the mucous membranes of the mouth, nose, and throat, or with tender skin (Souder 1963).

Aglaonema Schott cv. Parrot Jungle

[Information available but not yet included in database]

Alocasia G.Don
Elephant's Ear

Members of this genus are irritant on account of their high content of needle-like calcium oxalate crystals (Burkill 1935), although the sap of these plants has also been described as having a severe stinging effect on bare skin (von Reis Altschul 1973).

Several species are cultivated under the collective name of elephant's ears, referring to the shape of the leaves, but the term is also used for species of Begonia L. (fam. Begoniaceae).

Alocasia cucullata G.Don
[syns Alocasia cucullata Schott, Arum cucullatum L.]
Chinese Ape, Chinese Taro


Alocasia lowii Hook.


Alocasia sanderiana hort.

These species have been recorded as being irritant (Burkill 1935, Souder 1963).

Alocasia denudata Engl.

This species has been recorded as being irritant (Burkill 1935, Uphof 1959). Perry & Metzger (1980) note that the species has been used as an irritant in dart poison and is also a contact poison since if the powdered plant is mixed with bamboo hairs and rubbed over the body, severe itching and sometimes death may occur.

Alocasia indica Schott
Indomalayan Alocasia

This species has been recorded as being irritant (Souder 1963). The rhizome may be used as a rubefacient (Perry & Metzger 1980).

Alocasia macrorrhizos G.Don
[syns Arum macrorrhizum L., Alocasia macrorrhiza Schott, Colocasia macrorrhiza Schott]
Giant Alocasia, Giant Elephant's Ears, Giant Taro, Taro, Cunjevoi, Cunjerboy, Ape, Spoon Lily, Australian Cabbage

The young plant appears to be relatively innocuous but the mature plant can cause severe dermatitis, apparently because of its content of calcium oxalate raphides as well as unknown poison. Chewing any part of the plant causes swelling of the lips and tongue, and merely to touch the lips after handling the plant is painful. Eating a leaf has caused the death of a child through suffocation through swelling of the throat (Cleland 1914, Cleland & Lee 1963).

The whole plant is irritant; the sap of the leaves and petioles will blister the lips (MacPherson 1929) and is powerfully and sometimes destructively irritant to the eyes (Everist 1972, Arnold 1968, Francis & Southcott 1967, Souder 1963, Hurst 1942). The sliced tubers and leaves may be used as a rubefacient, and the acrid juice has been used to combat the caustic effect of the sap of Melanorrhoea laccifera Pierre (see Gluta laccifera Ding Hou, fam. Anacardiaceae) (Perry & Metzger 1980).

Alocasia portei Becc. & Engl.
[syn. Schizocasia portei Schott]

von Reis Altschul (1973) refers to a plant thought to be Schizocasia portei as having irritant juice.

Amorphophallus campanulatus Blume
Zamindkand, Telingo Potato, Telugu Potato, Elephant's Foot

The tubers contain abundant calcium oxalate raphides which are less abundant in those varieties cultivated for food use (Burkill 1935), but which can nevertheless cause pruritus, erythema, and whealing in those who handle them. Chewing the raw tuber may cause a burning sensation in the mouth, and urticaria may develop later.

An acrid, irritant juice is present in the tubers which may be rendered harmless by thorough washing and boiling (Nadkarni 1976). Both the seeds and the tubers have been used as counter-irritants (Behl et al. 1966).

Amorphophallus prainii Hook.f.

This species is reported to irritate the oral cavity when eaten (Burkill 1935).

Amorphophallus rivieri Durand
[syns Conophallus konjak Schott, Amorphophallus konjac K.Koch]
Devil's Tongue, Leopard Palm, Umbrella Arum, Snake Palm

The sap of the flower produces marked itching (von Reis Altschul 1973).

Amorphophallus sylvaticus Kunth
[syn. Synantherias sylvaticus Schott]
Wild Suran

The fruit causes a lasting burning of the tongue and lips together with salivation and numbness. In Indian indigenous medicine, the crushed seeds are applied externally to bruises and also into cavities in teeth as an analgesic (Nadkarni 1976).

Amorphophallus variabilis Blume

The tubers of this species are considered to be inedible except in Java where they are eaten after suitable preparation (Burkill 1935).

Anthurium Schott

The genus has been classified by Engler in the sub-family Pothoideae which is characterised by possessing neither latex nor raphides of calcium oxalate (Willis 1973). However, this is contradicted by other publications that describe an unusual phenomenon, which is widespread among aroids, namely the presence of raphide crystals associated with pollen. The following is a representative list of Anthurium species reported by Barabé et al. (2004) to yield pollen mixed with calcium oxalate raphides:

Anthurium acaule Schott
[syn. Pothos acaulis Jacq.]
Anthurium crystallinum Linden & André
Anthurium magnificum Linden
Anthurium polyrrhizum K.Koch & Augustin
Anthurium signatum K.Koch & Mathieu
Anthurium spectabile Schott 

The dermatological significance of these calcium oxalate raphides remains to be established.

Anthurium andraeanum Linden
Flamingo Lily, Oilcloth Flower

Souder (1963) included this species in a list of aroids containing microscopic stinging crystals of calcium oxalate.

Anthurium × ferrierense Bergman

This plant is listed as irritant by Pammel (1911).

Anthurium gracile Schott
[syns Anthurium rudgeanum Schott, Anthurium scolopendrinum Kunth, Pothos gracilis Rudge, Pothos scolopendrinus Desv. ex Ham.]
Red Pearls Anthurium

[Information available but not yet included in database]

Arisaema Mart.
Voodoo Lily

The genus contains about 150 species. Lewis & Elvin-Lewis (1977) note that the plants, and in particular the rhizomes, are poisonous on ingestion. The rhizomes contain abundant irritating calcium oxalate crystals but are edible if suitably prepared (Burkill 1935).

Arisaema concinnum Schott


Arisaema dracontium Schott
Green Dragon, Dragonroot

Both plants are irritant (Burkill 1935).

Arisaema jacquemontii Blume

The juice from the tubers is applied to the skin by the Khasi and Garo tribes of Meghalaya, India in the treatment of ringworm and other skin diseases (Rao 1981).

Arisaema japonicum Blume


Arisaema ringens Schott


Arisaema thunbergii Blume

The plants are irritant but their roots also have a numbing effect on the skin and were used in China as ingredients of a local anaesthetic preparation applied to abscesses before these were opened surgically (Maxwell 1929).

Arisaema speciosum Mart.
Jack-in-the-Pulpit, Cobra Lily

The tuber is said to be violently irritant (Behl et al. 1966).

The common name cobra lily is also used for Darlingtonia californica Torr. (fam. Sarraceniaceae).

Arisaema stewardsonii Britton

The rhizomes are said to be particularly irritant (Kingsbury 1964).

Arisaema tortuosum Schott

This species is described as being violently irritant (Behl et al. 1966).

Arisaema triphyllum Schott subsp. triphyllum
[syns Alocasia atrorubens Raf., Arisaema atrorubens Blume, Arum triphyllum L., etc.]
Indian Turnip, Dragonroot, Jack-in-the-Pulpit, Pepper Turnip, Bog Onion, Brown Dragon, Starchwort, American Wake Robin

The leaves and tubers can produce an irritant dermatitis (Muenscher 1951, McCord 1962, Kingsbury 1964, Hardin & Arena 1974) and vesication (MacPherson 1929). Wren (1975) states that the root has a burning and acrid taste.

[Further information available but not yet included in database]

Richard J. Schmidt

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