(Daisy or Sunflower family)
- Sigesbeckia orientalis L.
The juice of the fresh herb applied as a dressing to wounds leaves a varnish-like coating as it dries (Quisumbing 1951).
Orientin, a potentially allergenic sesquiterpene lactone, has been reported from this species.
- Silybum Adans.
Two species are indigenous to the Mediterranean region, but S. marianum Gaertner is also distributed over the pampas of South America where it was introduced.
- Silybum marianum Gaertner
- (syn. Carduus marianus L.)
- St Mary's Thistle, Blessed Thistle, Milk Thistle, Holy Thistle, Our Lady's Milk Thistle
This plant has large prickly leaves, as is suggested by its common names, and leathery involucral bracts each bearing a stout spine. It can cause mechanical injury (Pammel 1911). Díaz (1976) describes the plant as caustic.
Silymarin, which is obtained by extraction of the seeds, is used in Europe in the treatment of hepatic disorders. It contains silybin, a flavonoid with a protective function against experimentally induced hepatotoxicity induced by phalloidin (Wade 1977).
- Simsia annectens Blake
The hairs on the stems have a slightly stinging property (von Reis Altschul 1973).
- Solidago L.
- Golden Rod
There are about 100 species belonging to this genus which is classified in the tribe Astereae. All but one are natives of North America. The species are difficult to identify because of their tendency to hybridise both in the wild and under cultivation. Most commonly grown for ornamental purposes in herbaceous borders are hybrids and varieties of S. canadensis L. An intergeneric hybrid between an unknown Solidago species and Aster ptarmicoides Torrey & A. Gray, known as x Solidaster luteus Green (syns x Asterago lutea Everett, Aster hybridus E.H. Krause var luteus hort.), is also very popular.
White (1887) observed several cases of dermatitis in persons who handled Solidago species, but was unable to exclude inadvertent exposure to Toxicodendron Mill. (fam. Anacardiaceae). Two positive patch test reactions to Solidago were recorded by Hjorth (1968). Underwood & Gaul (1948) observed three cases of contact dermatitis from golden rod, with strongly positive patch test reactions.
- Solidago odora Aiton
This plant from eastern North America has been used medicinally; the volatile oil derived from it is irritant and rubefacient (Anon 1884). The plant yields an oil of perfumery (Arctander 1960).
- Solidago gigantea Aiton ssp serotina McNeill
- (syn. Solidago serotina Aiton)
This taxon is widely naturalised in Europe.
In an investigation of "weed dermatitis", three of 50 patients showed positive patch test reactions to an extract of this species (Shelmire 1939).
- Solidago virgaurea L.
This very variable European species has produced maculopapular dermatitis with itching and a burning sensation of the skin of field-workers three to twelve hours after hay making. The irritant is said to be carried by the pollen (Schwartz et al. 1957). The flower heads tend to accumulate extraneous pollen from other plants.
Frain-Bell & Johnson (1979) observed positive patch test reactions to the oleoresin from this species in 8 from 55 patients with the photosensitivity dermatitis and actinic reticuloid syndrome.
- Soliva pterosperma Less.
- Bindii, Jo-Jo
In Australia, children developed papular urticaria on the exposed and pressure areas of the body from the hairy spines of the seeds. In affected patients, but not in controls, pricking the skin with the bindii seed reproduced the clinical lesions (Commens et al. 1982).
- Spilanthes Jacq.
About 60 species are found in tropical America, Africa, the Malay Peninsula, Borneo, and northern Australia. Spilanthol, which has local anaesthetic properties, has been isolated from the flowers of Spilanthes acmella Murray (Dalziel 1937).
- Tagetes L.
Fifty species are natives of the warmer parts of the Americas. The genus is classified in the tribe Calenduleae.
Gerarde (1636), referring to French and African Marigolds, cited Dodonaeus for the statement "I did see a boy whose lippes and mouth when he began to chew the floures did swell extremely, … we gaue to a cat the floures with their cups, tempered with fresh cheese, she forthwith mightely swelled, and a little while after died". Hjorth (1968) observed one positive patch test reaction in seven patients tested.
Two intensely fluorescent compounds isolated from Tagetes roots were found to be phototoxic to Candida albicans, and were identified as bithienyl and α-terthienyl (Chan et al. 1975). α-Terthienyl (1% in ethanol) applied to the skin, covered with petrolatum, and irradiated with UVA light evoked, after about 15 minutes, erythema, blistering, and hyperpigmentation in a biphasic response (Chan et al. 1975, Towers et al. 1977b, Chan et al. 1977, Towers et al. 1979). This compound, together with a number of polyacetylenes, show UV-mediated phototoxicity to Candida albicans, but the polyacetylenes did not have phototoxic properties when applied to human skin (Towers et al. 1979). α-Terthienyl inhibits DNA repair in UV-irradiated human fibroblasts in culture (Stich et al. 1975), but did not induce chromosome abberations nor sister chromatid exchange in Syrian hamster (BKH-21) cells (MacRae et al. 1980a). It is also phototoxic to nematodes (Gommers 1972, Gommers & Geerlings 1973, Towers 1980).
- Tagetes coronopifolia Willd.
- Tagetes elliptica Sm.
α-Terthienyl, a phototoxic thiophene (see Tagetes L. above), has been reported from these species (Chan et al. 1979).
- Tagetes erecta L.
- African Marigold, Big Marigold, Aztec Marigold
African marigolds are widely grown for ornamental purposes, mostly as named cultivars.
According to Behl et al. (1966), the leaves are irritant to some individuals. The odour of marigolds, in the absence of pollen, has been stated to cause symptoms of pollinosis and asthma in two patients respectively (Biederman 1937). A species of Cosmos Cav. had a similar effect in one of them. Crown of Gold marigold, which has odourless foliage, had no ill effect.
Zechmeister & Sease (1947) isolated α-terthienyl from the petals of a "Lemon" variety of African marigold, but could not detect the compound in the petals of other varieties growing in the same field. See also Tagetes L. above). Gommers & Voor in't Holt (1976) also reported the presence of α-terthienyl in this species.
- Tagetes filifolia Lagasca
- Irish Lace
- Tagetes gracilis DC.
- Tagetes incida
- Tagetes jaliscensis Greenman
- Tagetes lemmoni A. Gray
- Tagetes lucida Cav.
- Sweet-Scented Marigold, Sweet Mace
- Tagetes microglossa Benth.
α-Terthienyl, which is phototoxic to human skin (see Tagetes L. above), has been reported from these species (Bohlmann et al. 1973, Castro -A. and Castro -C. 1978, Bohlmann & Zdero 1979, Chan et al. 1979, Castro -C. & Munoz -C. 1982).
- Tagetes minuta L.
- (syns Tagetes glandulifera Schrank, Tagetes glandulosa Link)
- Stinking Roger, Muster-John-Henry
Maiden (1895) received a report that the juice or seeds of Tagetes glandulifera Schrank irritated the eyes; the irritation was said to last for three to four days. Also, the juice was irritating to the bare arms of men working amongst the plants, producing marks the same as freckles which later peeled off. Scott (1967) and Findlay (1967) report this species to be a common cause of dermatitis in South Africa. In three farmers, one female and two male, who had "weed dermatitis", positive patch test reactions to diluted extracts of the plant were observed. The active principle occurred in the acetone soluble fraction of the leaf and flower head. The fresh leaf and flower were both irritant by patch test. Patch tests to Tagetes erecta L. were negative. One of two patients who were tested showed a positive patch test reaction to pyrethrum (Chrysanthemum cinerariifolium Vis.). Two patients showed positive patch test reactions to the flower, negative to the leaf, of Chrysanthemum morifolium Ramat. Positive reactions were not augmented by exposure to ultraviolet light (Verhagen & Nyaga 1974). The leaf and stem were, however, found to be phototoxic for Candida albicans (Camm et al. 1975).
If the stem of this plant punctures the skin, the wound is said to become septic (Watt & Breyer-Brandwijk 1962 citing Webb 1948a).
The plant yields an oil of perfumery (Arctander 1960).
α-Terthienyl, which is phototoxic to human skin (see Tagetes L. above), has been reported from the roots of this species (Chan et al. 1979).
- Tagetes patula L.
- French Marigold
According to Behl et al. (1966), the leaves of this commonly cultivated plant are irritant to some persons. Patch tests carried out using the leaves of this species crushed in a small quantity of normal saline elicited positive reactions in 3 of 14 contact dermatitis patients tested in New Delhi, India (Singh et al. 1978).
The cultivar 'Legion of Honour' was reported as a cause of contact dermatitis by Harrison (1906).
The plant yields an oil of perfumery (Arctander 1960).
α-Terthienyl, which is phototoxic to human skin (see Tagetes L. above), has been reported from this species (Bohlmann et al. 1973, Gommers & Voor in't Holt 1976).
- Tagetes signatus Bartling
- Tagetes tenuifolia Cav.
- Signet Marigold
α-Terthienyl, which is phototoxic to human skin (see Tagetes L. above), has been reported from these species (Bohlmann et al. 1973, Gommers & Voor in't Holt 1976, Chan et al. 1979).