ARACEAE — 2
Arisarum - Dieffenbachia

(Arum family)

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Arisarum vulgare Targ.-Tozz.

[syn. Arum arisarum L.]

Arisaron, Cuckoo Pint

The irritant effects of this plant have been known for centuries. Ramazzini's account of genital dermatitis in an apothecary appears to have been plagiarised from Dioscorides (Mitchell 1974b).

Arum L.

The 15 species in this genus are found naturally in Europe. It is probable that all species contain an acrid and irritant poison as well as calcium oxalate raphides (MacPherson 1929). The sap causes dermatitis (Lampe & Fagerström 1968).

Many plants previously named Arum are now placed in other genera; many plants in other genera of the Araceae are popularly known as arums.

Arum italicum Mill.

Italian Arum

The sap contains crystals of calcium oxalate and is acutely irritant to the skin and to the mouth if chewed (Francis & Southcott 1967).

Arum maculatum L.

Cuckoo Pint, Lords and Ladies, Wake Robin, Adam and Eve

The starch prepared from the tubers and named Portland arrowroot was formerly used as food (Prime 1960). The poisonous principle is destroyed by cooking. Gerarde (1636), who referred to the plant as Arum vulgare, stated that "The most pure and white starch is made of the roots of Cuckow-pint; but most hurtfull to the hands of the Laundresse that hath the handling of it, for it choppeth, blistereth, and maketh the hands rough and rugged, and withall smarting." Parkinson (1640), referring to the "common wake robin without spots", which he distinguished from the "spotted wake robin", noted that " […] when the leaves beginne to spring yeeldeth a milky sappe being broken or cut: the whole plant is of a very sharpe and biting taste, pricking the tongue upon the tasting, no lesse than Netles doe the hands, and so abideth for a great while without alteration; the roote with the sharpenesse hath a very strange clamminesse in it, stiffening linnen, or any other thing whereon it is laid, no lesse than starch : and in former dayes, when the making of our ordinary starch (which is made of the branne of wheate) was not knowen, or frequent in use, the finest dames used the rootes hereof, to starch their linnen, which would so sting, exasperate and choppe the skinne of their servants hands that used it, that they could scarse get them smooth and whole with all the nointing they could doe, before they should use it againe." He noted also that the spotted wake robin is "more sharpe and fierce than [the common wake robin without spots]."

The acrid juice may cause dermatitis (North 1967) and also swelling of the tongue on contact, the dried plant being somewhat less irritant than the fresh material (Flück & Jaspersen-Schib 1976). The roots and berries have poisoned children in Europe (Lewis & Elvin-Lewis 1977).

Caladium Vent.

[syns Aphyllarum S.Moore, Phyllotaenium André]

Mother-in-Law Plant, Elephant's Ear, Angel Wing

There are 12 species, which are natives of tropical South America, and numerous named cultivars. Many have decorative foliage and are widely grown as house plants (Mabberley 2008). They are often incorrectly called colocasias (Lampe & Fagerström 1968).

Caladium bicolor Vent.

[syns Arum bicolor Aiton, Caladium amoenum Engl., Caladium macrophyllum Lem., Caladium spruceanum Schott, Cyrtospadix bicolor Britton & P.Wilson, Pteris scandens Roxb., etc.]

Angel Wings, Common Caladium, Elephant's Ear, Fancy-Leaved Caladium, Heart of Jesus, Corazon de Santa Maria

Morton (1962a) noted that all parts of these plants but particularly the leaves and bulb, when raw, contain irritant crystals of calcium oxalate. When cooked, both the leaves and bulbs have been eaten as vegetables in tropical America and the West Indies. Souder (1963) included Caladium bicolor in a list of aroids described as containing microscopic stinging crystals of calcium oxalate that are intensely irritating when brought in contact with mucous membranes of the mouth, nose and throat, even in contact with tender skin.

Caladium picturatum K.Koch & C.D.Bouché

[syns Caladium aturense G.S.Bunting, Caladium hastatum Lem., Caladium porphyroneuron K.Koch, Caladium sagittatum L.Linden & Rodigas]

Angel Wings, Elephant's Ear, Fancy-Leaved Caladium, Heart of Jesus, Mottled Caladium

Morton (1962a) noted that all parts of these plants but particularly the leaves and bulb, when raw, contain irritant crystals of calcium oxalate. When cooked, both the leaves and bulbs have been eaten as vegetables in tropical America and the West Indies.

Calla palustris L.

Wild Canna, Water Arum, Water Dragon

This species is a native of northern temperate and sub-arctic regions. The genus is monotypic.

The plant, particularly its rhizome, is irritant (Kingsbury 1964) and poisonous on ingestion (Lewis & Elvin-Lewis 1977).

Calla lily is a common name for Zantedeschia aethiopica Spreng. (syn. Richardia africana Kunth).

Colocasia esculenta Schott

[syns Colocasia antiquorum Schott, Arum colocasia L.]

Taro, Cocco, Coco-Yam, Eddoes, Elephant's Ear, Dasheen, Malanga, Papa Malanga

The tubers of this plant form a valuable food crop widely known as taro. They do, however, contain needle-like raphides of calcium oxalate in the superficial tissues, which can be removed by peeling. This may lead to irritation of the hands, the risk being lessened by peeling underwater (Burkill 1935). Calcium oxalate raphides are also present in the leaves and stems (Nadkarni 1976).

Ingestion of any part of the plant in the raw state causes great pain and swelling of the lips, tongue, and throat (Dahlgren & Standley 1944, Williamson 1955, Souder 1963, Francis & Southcott 1967, Arnold 1968).

The juice of this plant produced a positive patch test reaction in 2 of 53 patients who had hand dermatitis suspected to have been caused by vegetables (Sinha et al. 1977). Nadkarni (1976) notes that the juice of the petioles is rubefacient.

Culcasia scandens P.Beauv.

The sap of the stems irritates the skin (Williamson 1955).

Cyrtosperma chamissonis Merr.

[syn. Arisacontis chamissonis Schott]

Giant Taro, Baba

The raw tuber is irritant to the skin and to the mucous membrane of the mouth (Souder 1963).

Dieffenbachia Schott

Dumb Cane, Dumb Plant, Tuft Root, Mother-in-Law's Tongue Plant, Otó de Lagarto, Rábano, Cimarrón

There are about 30 species, natives of tropical America and the West Indies. Certain species are widely cultivated for their decorative foliage, being commonly seen in hotel lobbies, waiting rooms, restaurants, and such places.

Contact with the bruised or broken plant material may cause severe blistering and inflammation of the skin (Delph 1937, Dahlgren & Standley 1944, Occhioni & Rizzini 1958, Barnes & Fox 1955). All species contain calcium oxalate raphides (Souder 1963), but their irritant effect on skin and mucous membranes are believed to be increased by the presence of other substances (Manno et al. 1967, Fochtman et al. 1969, Walter & Khanna 1972). However, not all species have an irritant sap (Arnold 1968).

Dieffenbachia aurantiaca Engl.

Dieffenbachia longispatha Engl. & K.Krause

Dieffenbachia oerstedtii Schott

Dieffenbachia pittieri Engl. & K.Krause

These species are said to be irritant (Allen 1943).

Dieffenbachia exotica hort.

The name Dieffenbachia exotica is of no botanical standing but is nevertheless used in the USA and Canada.

Tests on rabbit eyes showed mild irritation with the juice of this plant (Manno et al. 1967, Fochtman et al. 1969).

Dieffenbachia paludicola N.E.Br. ex Gleason

Irritation of the hands is produced by raphides of calcium oxalate when split portions of this plant are handled (von Reis Altschul 1973).

Dieffenbachia seguine (Jacq.) Schott

[syns Arum seguine Jacq., Caladium seguine (Jacq.) Vent., Dieffenbachia amoena W.Bull, Dieffenbachia maculata (G.Lodd.) Sweet, Dieffenbachia picta Schott]

Dumb Cane, Mother-in-Law Plant

If the stem is bitten, the resulting bullous stomatitis is of such severity that it renders the victim speechless (Francis & Southcott 1967). There may also be oedema of the skin around the mouth. Similar reactions have been reported to both species (Burkill 1935, Drach & Maloney 1963, Behl et al. 1966, Everist 1972, Faivre et al. 1974). Sporadic cases of severe stomatitis caused by these plants continue to be reported (Jaspersen-Schib et al. 1996).

Experiments in rats have shown that pretreatment with antihistamines affords some protection against the effects of the juice on the oral cavity, but treatment with cortisone merely delays the reaction (Fochtman et al. 1969).

Piffard (1881), referring to Caladium seguinum, noted that the juice of the leaves when applied to the skin produces intense itching and burning, and afterwards inflammation. Brache & Aquino (1978), referring to Dieffenbachia maculata, report that this species is among the 14 commoner causes of plant dermatitis in the Dominican Republic (where the plant is known as matapuerco or brazo ponderoso). Burkill (1935) and von Reis Altschul (1973) also report that the juice of D. seguine irritates the skin. Tests on rabbit eyes have shown severe irritation with the juice of D. picta (Manno et al. 1967, Fochtman et al. 1969), the toxicity being associated with a labile protein-like substance present in the sap. Walter & Khanna (1972) have isolated a proteinase, named dumbcain, from Dieffenbachia amoena, Dieffenbachia picta and Dieffenbachia seguine, and consider that the irritant activity of these species could arise from the intradermal injection of the proteinase by the calcium oxalate raphides present in the plants.

Lynne-Davies & Mitchell (1974) applied portions of the fresh leaf from Dieffenbachia amoena to the backs of 2 males for 48 hours under occlusion. Neither irritant reactions nor delayed flares occurred.

The calcium oxalate raphides of Dieffenbachia picta leaves are present in two size ranges. The smaller raphides measure 10–20 µm in length and a little under 1 µm in diameter, and are contained within typical idioblast cells. The larger raphides measure 130–150 µm in length and about 3 µm in diameter, are sharply pointed at both ends, and are contained in unusual, randomly scattered capsular cells from which they may be expelled through the ends (Schmidt RJ 1981 — unpublished observation).

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