TAXON 21(I): 113-114. FEBRUARY 1972 HANDROANTHUS (BIGNONIACEAE): A CRITIQUE* A. H. Gentry** Summary This paper considers the latest attempt to dismember Tabebuia and demonstrates that the newly proposed genus Handroanthus does not merit generic distinction. The recent segregation from Tabebuia of Handroanthus (Mattos, 1970) as a new genus of Bignoniaceae has scarcely improved the taxonomy of that family. Having realized that the digitate-leaved Tabebuia species cannot be put into Tecoma as has been the wont of many Brazilian taxonomists since Martius' Flora Brasiliensis (Bureau & Schumann, 1896-1897), Mattos unfortunately failed to consult more recent authors who have clearly and repeatedly (e.g. Sprague & Sandwith, 1932; Gentry, 1969) demonstrated that these species cannot be separated from the simple-leaved species of Tabebuia. The only additional diagnostic character cited by Mattos for Handroanthus is an ovary cross section with 8-9 ovules per locule as opposed to 3-4 ovules per locule in Tabebuia. The characters cited are inadequate for specific let alone generic delimitation. Although the non-Brazilian species of Tabebuia are conveniently ignored by Mattos, numerous species fall squarely midway between his two genera; worse, many species and even individual trees fall into both of them! For example, T. pallida Miers has only 2 ovules per locule in ovary cross-section and may be simple-leaved, unifoliolate, 2-foliolate, 3-foliolate, or digitately 5-foliolate on the same plant. Tabebuia insignis (Miq.) Sandw. (known from Brazil as T. albiflora Ducke but untreated by Mattos) has had its simple-leaved form described as T. longipes Baker although Sandwith (1937) has shown that this form is at most a variety. Indeed every digitateleaved species of Tabebuia that I have observed passes through a simpleleaved juvenile form. Furthermore older generic names are already available for the digitate-leaved Tabebuia species should they be segregated (e.g. Couralia Splitg.). Moreover, even were Handroanthus to be accepted, many of its specific epithets would have to be changed or eliminated. Especially conspicuous is Handroanthus floccosus ("Kl.") Mattos: Tecoma floccosa K1. ex Bureau & Schumann, on which it is based, was shown more than a decade and a half ago (Sandwith, 1954) to be synonymous with Xylophragma seemanniana (Kuntze) Sandw. which is not even in the tribe Tecomeae. Presumably none of Sandwith's other important work was consulted either, since he showed that many of the specific epithets used in Handroanthus are junior synonyms (e.g. H. araliaceus (Cham.) Mattos is T. serratifolia (Vahl) * The author wishes to thank Dr. J. L. Reveal and Alan Atchley of the University of Maryland for bringing Handroanthus to his attention and acknowledges with appreciation the support of a National Science Foundation Graduate Fellowship. ** Missouri Botanical Garden, St. Louis, Missouri 63110, U.S.A. FEBRUARY 1972 113 Nichols). Handroanthuspentaphyllus (L.) Mattos is based on the illegitimate Bignonia pentaphylla L. (see Sandwith, 1954). Furthermore,the segregation of H. piutinga (Pilger) Mattos, H. odontodiscus (Bur. & Schumann)Mattos, and H. roseo-alba (Ridley) Mattos, all of which are synonyms of T. roseo-alba(Ridley) Sandw., is unjustified. An apparent over-relianceon the 73-year-old Flora Brasiliensistreatment is evident throughoutthe Handroanthuspaper. This may accountfor the author'sfailure to consult contemporarystudents of the Bignoniaceae and would explain the maintenanceof so many of the incorrect specific epithets used by Bureauand Schumann.Significantly, the illustrationsare taken (intact but unacknowledged)from figures in Flora Brasiliensis;a superficial comparisonof the four ovules per locule of an ovary crosssection in the illustrationof Tabebuiaobtusifoliawith the 8-9 ovules per locule in the Tecoma ochracea illustration might explain the use of this untenablecharacterin generic separation.It would seem that at the very least a consultationof the relevant works of such an outstandingauthority on the Bignoniaceaeas the late N. Y. Sandwith would have been in order before erecting a new genus in the family. The net effect of Handroanthusis the addition of twenty-seven new names to the already overburdened synonymy of Tabebuia. It is the author'ssincerehope that future studentsof the Bignoniaceaewill consider the case of Handroanthus before succumbingto further paroxysms of unwarrantedsplitting. References E. and SCHUMAN, K. 1896-1897 - Bignoniaceae in Martius, Flora Brasiliensis 8(2): 1-452. GENTRY, A. H. 1969 - Tabebuia: the tortuous history of a generic name (Bignoniaceae). Taxon 18(6): 635-642. MATTOS, J. R. 1970 - Handroanthus, um novo genero para os "Ipes" do Brasil. Loefgrenia BUREAU, 50: 1-4. SANDWITH,N. Y. 1937 - Notes on tropical American Bignoniaceae. Rec. des Tray. Bot. Neerl. 34: 205-232. SANDWITH,N. Y. 1954 - Contributions to the flora of tropical America: LVI. Further studies in Bignoniaceae. Kew Bull. 1953(4): 451-484. SPRAGUE, T. A. and SANDWITH, N. Y. 1932 - The Tabebuiasof British Guiana and Trinidad. Kew Bull. 1932(I): I8-28. 114 TAXONVOLUME21
