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(Dogbane or Vinca family)
- Epitaberna myrmoecia Schumann
This plant occurs throughout the tropical rain forests in the region of southern Cameroun in western Africa. Its caulinary swellings are inhabited almost invariably by an aggressive species of ant (Pachysima aethiops F. Smith, fam. Formicidae) with an exceedingly painful sting (Bequaert 1922). The consequence of handling the plant in its natural habitat, or even simply standing beneath its branches is likely be a pseudophytodermatitis caused by the bites and stings of the ant inhabiting this super-nettle. A review of this topic is provided by Schmidt (1985).
- Ervatamia cylindrocarpa King & Gamble
- (syn. Tabernaemontana cylindrocarpa Merr.)
The leaves of this species when pounded with rice (Oryza sativa L., fam. Gramineae) and turmeric (Curcuma longa L., fam. Zingiberaceae) have been used in Malaya to treat eczema and itch (Burkill 1935).
- Geissospermum sericeum Benth. & Hook. f.
The wood causes symptoms similar to those produced by Aspidosperma species (Freise 1937).
- Gonioma kamassi E.Mey.
- (syn. Tabernaemontana kamassi Ecklon)
- South African Boxwood, Knysna Boxwood
The hard timber from this South African tree has long been used as a substitute for European boxwood (Buxus sempervirens L., fam. Buxaceae) in the manufacture of shuttles, tool handles, and similar objects (Hausen 1981). Workers exposed to the dust of African boxwood developed alarming reactions including irritation of the eyes and nose, and also constitutional symptoms. Some developed asthma (Legge 1905, Legge 1907, Hay 1907). There is some confusion in the literature as to the botanical identity of the wood (Dixon 1911), it being initially believed that West African boxwood was the cause — see Nauclea diderrichii Merr., fam. Rubiaceae.
In the UK, following a recommendation in the Samuel Report of 1907 (Samuel et al. 1907), Gonioma kamassi wood dust was added to the list of causes of occupational diseases for which compensation could be claimed under the Workmen's Compensation Act 1906. Only a few cases have been compensated since other woods have largely replaced this in the trade (MacKenna & Horner 1954). In Australia, the timber was recognised in 1916 as a cause of industrial injury for which compensation could be claimed (Maiden 1917). In the USA in 1920-1930s, occupational dermatitis caused by Knysna boxwood was compensated by law only in Minnesota (Hausen 1981 citing Ganzoni 1929).
- Hancornia speciosa Gomes
The latex is believed to be effective against warts (Schultes 1979).
- Holarrhena pubescens Wall. ex G. Don
- (syns Echites antidysentericus Roth, Holarrhena antidysenterica Wall. ex A. DC., Holarrhena febrifuga Klotzsch, Nerium sinense Hunter ex Ridl., etc.)
- Bitter Oleander, Dysentery Rose Bay, White Angel, Arbre de Jasmin, Jasminbaum
The crude drug known variously as Kurchi, Conessi Bark, Tellicherri Bark, Holarrhena Bark, or Zhi Xie Mu derived from Holarrhena antidysenterica has been used in India and elsewhere in the treatment of amoebic dysentery. It contains conessine, a steroidal alkaloid that may be extracted from both the bark and the seeds (Remington et al. 1918, Todd 1967).
Research workers involved in the isolation of conessine from this plant, and in structural studies of the compound, have suffered from a contact dermatitis which was thought to be of an allergic nature (Jewers 1981).
There is much confusion in the literature as to the botanical identity of the crude drug, with many authors identifying Wrightia antidysenterica R. Br. as the source. This confusion was alluded to by Brown (1922) who cited an earlier article published in the Indian Medical Gazette in 1880.
- Macoubea guianensis Aublet
The wood causes symptoms similar to those produced by Aspidosperma species (Freise 1937).
- Malouetia naias M.E. Endress
- (syns Cameraria tamaquarina Aubl., Malouetia furfuracea Spruce ex Muell. Arg., Malouetia guianensis Klotzsch, Malouetia obtusiloba A. DC., Malouetia tamaquarina A. DC.)
Sóti et al. (1967) isolated conessine from Malouetia tamaquarina. Conessine is believed to have caused contact dermatitis in research workers (see Holarrhena antidysenterica above).
- Mandevilla anceps Woodson
- Mandevilla annulariifolia Woodson
The latex of these two species is caustic and has been used by South American Indians to remove warts (Schultes 1979).
- Mandevilla scabra Schumann
- (syn. Echites scabra Hoffsgg.)
The latex is said to have depilatory properties (Schultes 1979).
- Mandevilla stephanotidifolia Woodson
- Mandevilla subcarnosa Woodson
These species have caustic latex (Schultes 1979).
- Nerium oleander L.
- (syns Nerium indicum Mill., Nerium odoratum Lam., Nerium odorum Sol.)
- Oleander, Rose Bay, Scented Oleander, Laurier-Rose, Rosagine
The genus Nerium L. comprises a single species of which about 400 cultivars are known (Mabberley 2008). This variability has evidently contributed to some taxonomic confusion in the early dermatological literature.
Oleander is a source of cardiac glycosides, which render the plants extremely poisonous on ingestion. Oleandrin obtained from Nerium oleander L. is used similarly to digitalis (Wade 1977). Although its toxicity has been long known (see Watt & Breyer-Brandwijk 1962, Hausen 1981a), cases of accidental poisoning continue to occur (Jaspersen-Schib et al. 1996). Smoke from a fire of oleander wood is toxic (Allen 1943, Hurst 1942), and meat cooked on oleander skewers or over an oleander wood fire may become poisonous (Steyn 1934, Burkill 1935, Francis & Southcott 1967). In Florida, the burning of oleander trimmings is prohibited in some communities (Morton 1958). Honey made from the nectar is also reportedly toxic (Pammel 1911).
Notwithstanding its toxicity, this shrub is widely cultivated for its attractive flowers (Mabberley 2008). It is grown outside in warmer climates, and as a house or greenhouse plant in cooler regions (Hunt 1968/70). In relation to the frequency with which exposure to oleander occurs, rather few cases of dermatitis have been reported. In 1817, Bigelow wrote that the common oleander is said to affect some persons like poison ivy (Toxicodendron Mill. species, fam. Anacardiaceae), and Halsted (1899) reported similar effects. Piffard (1881) noted that local application of the crude drug to healthy skin produces vesication. The assertion made by Morton (1958) that "sensitive individuals contract dermatitis from contact with the plant" probably derives from this earlier literature. More recent reports (Dorsey 1962, Behl et al. 1966) concern mainly children who have been playing around the shrubs. According to Behl et al. (1966), the sap of Nerium indicum is irritant, and circumstantial evidence suggests that it may contain a sensitiser. Patch tests carried out using the leaves of Nerium odorum crushed in a small quantity of normal saline elicited positive reactions in 3 of 8 contact dermatitis patients tested in New Delhi, India (Singh et al. 1978). Hjorth (1968) obtained no positive patch tests to Nerium oleander in seven patients studied.
Dragendorff (1898), cited by Steyn (1934), recorded that the leaves and bark are used externally in eczemas. According to Felter & Lloyd (1898), pediculi are destroyed by a decoction of the leaves. Muenscher (1951) noted that the leaf has been used in northern Africa in the treatment of scabies, but was also reported to produce dermatitis. Nagata (1971) records the use in Hawaii of Nerium indicum in the treatment of skin diseases. Extracts of Nerium odorum roots have been used in Indian indigenous medicine in the treatment of leprosy and other skin diseases (Nadkarni 1976).
[Further information available but not yet included in database]
- Pachypodium Lindl.
This genus comprises 25 species found mainly in Madagascar but also in southern and south-western Africa (Mabberley 2008). A number may be found in collections of succulents.
Some are exceedingly thorny, their trunks and branches completely covered with spines. The following species are spiny (Hutchinson 1946; Chittenden 1951; Findlay 1962; Menninger 1967; Palgrave 1956):
- Pachypodium densiflorum Baker
- Pachypodium lamerei Drake — Bottle Tree, Club Foot, Madagascar Palm, Pachypodium de Madagascar, Madagaskarpalme
- (syns Pachypodium champenoisianum Boiteau, Pachypodium ramosum Costantin & Bois)
- Pachypodium lealii Welw. — Bottle Tree, Bumbo
- Pachypodium lealii Welw. ssp saundersii Rowley — Kudu Lily, Star of the Lundi
- (syn. Pachypodium saundersii N.E. Br.)
- Pachypodium namaquanum Welw. — Club Foot, Elephant's Trunk, Half Men, Ghost Men
- Pachypodium rosulatum Baker
- Pachypodium succulentum Sweet
Whilst Hunt (1968/70) states that Pachypodium giganteum Engl. is spiny, Menninger (1967) describes this species as fat and ugly and having no thorns.
- Parameria vulneraria Radlk.
This climber found in South East Asia and Malaysia yields Balsamo de Tagulaway, otherwise known as Cebur Balsam or Cebu Balsam, which is prepared by extracting the bark and leaves with hot coconut oil. The peculiarly odorous yellow-white liquid so obtained is applied to wounds and cutaneous affections (Felter & Lloyd 1898).