- Tabebuia Gomes ex DC.
This is a genus of about 74 species of trees found in the West Indies and from Mexico to northern Argentina. The lapacho group or series of the genus Tabebuia consists of about 20 species and occurs in practically every Latin American country except Chile. The timber from this group yields a yellow-green compound named lapachol which is usually visible on planed surfaces, confined to the vessel lines. In some specimens, this compound may cover the entire surface during sawing (Kukachka 1970). Lapachol is a known elicitor of contact dermatitis (Schulz et al. 1977).
Many species provide valuable timber, and most of them, perhaps all can cause dermatitis in some individuals (Orsler 1973). However, the haphazard use of trade or popular names in many reports, together with the many nomenclatural changes in their botanical names makes retrospective identification of the species involved rather difficult.
- Tabebuia araliacea Morong & Britton
- [syn. Tecoma araliacea DC.]
Matthes & Schreiber (1914) found that the wood from this species contains lapachol together with other unidentified compounds that were also capable of producing itching and inflammation of the skin. Lapachol is a known elicitor of contact dermatitis (Schulz et al. 1977).
- Tabebuia avellanedae Lorentz
- [syns Tabebuia ipe Standley, Tecoma ipe Mart.]
- Ipé, Ipé Preto, Lapacho, Ipé Tabaco
This species provides a valuable timber that is exported to Europe only in small amounts (Hausen 1981).
Freise (1932, 1936) reported 83 cases of dermatitis with respiratory and other constitutional symptoms. When tested on affected persons, the fresh sawdust produced erythema and papules within a few hours, and this developed into a severe weeping and crusting dermatitis that took several weeks to clear. He also reported three human deaths and expulsion of worms from swallowing the wood dust. Cordero & Lynch (1951) also reported occupational dermatitis with constitutional symptoms from the wood of this species. The sawdust irritates the nose, lungs, and skin - colouring the skin yellow-green. Washing with soap causes a change of colour to bright red (Woolston & Phillips 1955).
Sandermann & Dietrichs (1957) reported the presence of lapachenole and lapachol in the timber. Burnett & Thomson (1967) have isolated deoxylapachol and lapachenole, both of which are potent contact allergens (Schulz et al. 1977), from the heartwood together with several quinonoid compounds.
- Tabebuia chrysantha Nicholson
- [syn. Bignonia chrysantha Jacq.]
An extract of the heartwood of this species was found to contain lapachenole as a major constituent. Lapachol was also present as a minor constituent (Burnett & Thomson 1968). Lapachenole is a potent contact allergen (Schulz et al. 1977).
- Tabebuia chrysotricha Standley
- [syn. Tecoma chrysotricha Mart.]
- Ipé Tabaco
The timber from this species was reported by Freise (1932) to produce dermatitis.
- Tabebuia guayacan Hemsley
The heartwood of this species contains lapachol (Manners & Jurd 1976), a known elicitor of contact dermatitis (Schulz et al. 1977).
- Tabebuia heterophylla Britton
- [syns Bignonia pentaphylla L., Tabebuia pentaphylla Hemsley, Tecoma pentaphylla Juss., Bignonia leucoxylon L.]
- Roble, White Cedar
In Cuba, the buds and young leaves of Bignonia leucoxylon or Bignonia pentaphylla, rubbed on the affected parts, are considered to be an antidote for poisoning by manchineel (Hippomane mancinella L., fam. Euphorbiaceae) (Hamilton 1846, Standley 1926).
Zafiropoulo et al. (1968) have reported dermatitis from handling the timber. Oesterle (1916) reported the presence of lapachol in a timber identified as Bignonia leucoxylon and given the name greenheart. Lapachol is a known elicitor of contact dermatitis (Schulz et al. 1977).
- Tabebuia impetiginosa Standley
- [syn. Tecoma impetiginosa Mart.]
- Ipé Roxo
- Tabebuia insignis Sandw.
- [syn. Tecoma insignis Miq.]
- Ipé Tabaco
Hausen (1973) reports that these species contain lapachol, which is a known elicitor of contact dermatitis (Schulz et al. 1977).
- Tabebuia palmeri Rose
The sawdust of this species can cause dermatitis (Ortega 1926).
- Tabebuia rosea DC.
- [syn. Tecoma rosea Bertol.]
- Pink Poui, May Flower, Pink Trumpet
The roots, heartwood, and stem bark of this species contain lapachol (Joshi et al. 1973b, 1976, 1977b), a known elicitor of contact dermatitis (Schulz et al. 1977).
- Tabebuia serratifolia Nicholson
- [syn. Tecoma serratifolia G.Don]
- Bethabara, Surinam Greenheart, Guayacan
The timber is harder and more durable than that of other species of Tabebuia available in commerce.
Dermatitis in a joiner working with bethabara wood (the botanical identity of which was not stated) has been described (Weitbrecht 1967, Hausen et al. 1971). Deoxylapachol isolated from the wood provoked a positive patch test reaction in the patient; the reaction was considered to be of an irritant nature (Hausen et al. 1971).
- Tecoma Juss.
Once a much larger genus, Tecoma now comprises some 16 species which are to be found in tropical America. Although reclassification was carried out on morphological grounds, many of the species transferred have been found to contain lapachol and are now included in Tabebuia Gomes.
- Tecoma stans Kunth
- [syns Stenolobium stans Seem., Bignonia stans L.]
- Elderbush, Ginger Thomas, Yellow Cedar, Yellow Elder, Yellow Bells
Dohnal (1976) observed that the callus produced when growing this species in tissue culture contained traces of lapachol. Lapachol is a known elicitor of contact dermatitis (Schulz et al. 1977).
- Tecomella undulata Seem.
- [syn. Tecoma undulata G.Don]
The roots, heartwood, and bark contain lapachol (Singh et al. 1972, Joshi & Singh 1974, 1977, Joshi et al. 1977c). Lapachol is a known elicitor of contact dermatitis (Schulz et al. 1977).
- Zeyheria Mart.
- [syn. Zeyhera DC.]
This genus comprises two species which are natives of Brazil.
- Zeyheria montana Mart.
- [syns Bignonia digitalis Vell., Zeyheria digitalis (Vell.) Hoehne & Kuhlm.]
The stem of this shrub has been found to contain lapachol (Chagas Da Silveira et al. 1975). Lapachol is a known elicitor of contact dermatitis (Schulz et al. 1977).
- Zeyheria tuberculosa Bureau
- [syn. Bignonia tuberculosa Vell.]
Duarte Weinberg et al. (1976) isolated lapachol from the wood of this tree. Lapachol is a known elicitor of contact dermatitis (Schulz et al. 1977).