A synopsis of Ipomoea (Convolvulaceae)
in the Americas

Daniel F. Austin and Zósimo Huáman: A synopsis of Ipomoea (Convolvulaceae) in the Americas. Taxon 45:3-38. 1996. A total of 342 taxa (332 species, five varieties, five subspecies) currently are recognized in the Americas, with the caveat that additional taxa exist that are unstudied and undescribed. Those species recognized are placed, when possible, in infrageneric categories. Known distributions are given for each taxon.

The genus Ipomoea comprises the largest number of species within the Convolvulaceae. Throughout the world Ipomoea is usually estimated to contain ca. 500 species (e.g., Mabberley, 1989; McDonald & Mabry, 1992). After our compilation, we believe Ipomoea is more likely to contain 600-700 species. Over half of the species are concentrated in the Americas, where the total may approach 500 taxa, mostly native and a few introduced. Although there are recent publications dealing with Ipomoea in the floras of several American countries (O'Donell, 1941-1960b; Austin, 1975-1991a,b; Austin & Cavalcante, 1982; Austin & al., 1986; McDonald, 1978-1995; McDonald & Austin, 1990; McDonald & Mabry, 1992; Wilkin, 1995), there is no single reference summarizing all the species currently recognized in the western hemisphere. The purpose of this publication is to make available an updated list with relationships of American Ipomoea species examined thus far. There certainly are more species in the Americas than recognized here, especially in Brazil, Bolivia and Paraguay, but many of these have not been studied since Meisner (1869). Moreover, there are species remaining undescribed and/or undiscovered. Infrageneric placement is given, where known, and a documented American geographical range is provided for each species.

Taxonomic considerations

Infrageneric classification of Ipomoea has changed markedly since the taxa were typified by Verdcourt (1957) and Austin (1975a). Critical to an understanding of the infrageneric taxa in the Americas were the recent detailed studies of the Mexican species by McDonald (1978-1995). McDonald1s studies resolved a problem noted by Austin (1979) with what had previously been called I. sect. Orthipomoea in the New World. Because of the way in which Verdcourt (1957) typified I. sect. Orthipomoea, he excluded the American element originally included by Choisy (1845) and confined the taxon to the Old World. Thus, several New World species have been incorrectly placed inI. sect. Orthipomoea. McDonald (1991) has properly placed those American species within his ÎTricolor group1 in I. subg. Quamoclit. Moreover, recent investigations by McPherson (1979, 1980, 1981), McDonald (1982b-1995), McDonald & Austin (1990), and McDonald & Mabry (1992) have indicated other rearrangements of the American species, and some new infrageneric taxa have been created. Some of the taxa recognized here have been validly named; others have not. In anticipation of their eventual valid publication by their authors, those names in single quotes here are used informally.

The categories recently discussed by Austin (1979, 1980) and McDonald (1991) mostly are based on names created and discussed by Choisy (1845), House (1908b), Ooststroom (1953) and Verdcourt (1957, 1963). The chloroplast DNA analysis by McDonald & Mabry (1992) and studies currently under way by Austin and Wilkin indicate that there remain problems with some of the sections and series in the system used here. In spite of those problems of formerly unrecognized convergences and parallelisms, the system used here has existed for over 100 years in one form or another. No major changes will be initiated in the overall arrangement until more research has been finished.

As now understood, the American members of Ipomoea comprise three subgenera. McDonald & Mabry (1992) suggest that another New World subgenus may be needed, but that has not been formally established. Within the current three subgenera are nine sections, six of which [Calonyction, Exogonium, 'Microsepalae', Mina, Leptocallis, 'Tricolor'] were originally confined to the Americas before some were dispersed as cultigens, medicinal plants and weeds. Ipomoea ser. Batatas also historically had all but one of its species endemic to the Americas (Austin, 1991b). Several other series are, or were historically, endemic to the Americas, e.g., Anisomeres, Arborescentes, Bombycospermum, Mirandinae, Setosae.

The taxa recognized (Table 1) account for all the New World subdivisions of Ipomoea that have been proposed. There are several Old World subdivisions that were recognized by Verdcourt (1957, 1963), some of which have not been validly named under the Code (Greuter & al., 1994) in spite of being discussed by Austin (1975a, 1979, 1980) and Gonçalves (1987), and perhaps others. Sebsebe Demissew (Addis Abeba) is currently working on the family for the Flora of Ethiopia and will be providing a summary of African infrageneric taxa.

In the scheme presented here several changes have been made in the classification proposed earlier. Publications by Austin (1975a, 1979, 1980) recognized the taxon Ipomoea sect. Suffruticosae (Choisy) D. F. Austin that should have been placed in synonymy under Turbina Rafinesque (cf. Meeuse, 1957). Although some (e.g., McPherson, 1979) do not recognize Turbina as a genus distinct from Ipomoea, data on various species indicate to us that it is best kept separate (Verdcourt, 1958, 1963; Stearn, 1977; Pedraza, 1983; Heine, 1984; Gonçalves, 1987; Mandrile & Dongiorno de Pfirter, 1990; Austin & Staples, 1991; Deroin, 1992). Wilkin (pers. comm.) will be presenting an argument for a different disposition.

McPherson (1979) used informal group designations for all the subdivisions he recognized as had Matuda (1963-1966). McDonald (1991) first continued use of those informal designations and then equated some of them with formal names (McDonald & Mabry, 1992). After examination of the data, it has become clear that the correct name for what McPherson (1979) called the 'Microsticta group' is I. ser. Eriospermum. There seems to be no reason to keep I. ser. Dactylophyllae (type species I. horsfalliae Hooker) separate from I. ser. Eriospermum (type species I. digitata L.). These changes have been made. Further study may indicate subdivision of I. ser. Eriospermum, but current data do not indicate how that might be done.

Ipomoea ser. Anisomeres has been recognized by many previous students of the family, including House (1908b), Austin (1975a, 1979, 1980), and McDonald (1991). Austin is completing a revision that will redefine this taxon by excluding some species previously included in it and including one that had not before been associated with it.

McDonald & Austin (1990) first maintained that I. sect. Batatas was improperly placed in I. subg. Quamoclit. Their morphological study, the subsequent chloroplast DNA analysis by McDonald & Mabry (1992), and the morphological/palynological study by Austin & Wilkin (1993) all indicate that I. sect. Batatas is better placed in I. subg. Eriospermum near ser. Setosae. Moreover, all data indicate that the group should be lower in rank to better reflect this affinity. This change is made below.

McDonald & Mabry (1992) found DNA evidence that I. ser. Tyrianthinae is not closely allied with I. sect. Pharbitis. The correct position is near I. sect. Calonyction and the 'Tricolor' group. Even then, I. ser. Tyrianthinae seems to be heterogeneous to us, and McDonald (pers. comm.) agrees.

McDonald (1991) included several American species in Ipomoea ser. Ipomoea. Earlier Verdcourt (1957, 1963) and Austin (1975a, 1979, 1980a,b) had considered that series to be confined to the Old World. The study by McDonald & Mabry (1992) subsequently placed some of the species in question in I. ser. Pharbitis (e.g., I. ampullacea, I. mairetii). McDonald (pers. comm., 1994) has reconsidered the situation, and now agrees that no New World species belong to I. ser. Ipomoea. There are morphological similarities between several New and Old World species, some of which are endemic to the Americas, and others to the Old World. Still, no species in I. ser. Ipomoea occurred in both hemispheres before they were dispersed in historical times by humans. These similarities seem to reflect convergence, and the American species formerly included in I. ser. Ipomoea have been moved to I. ser. Pharbitis.

McDonald (1995) has recognized I. sect. Leptocallis (G. Don) J. A. McDonald. We think that this should be called I. ser. Pedatisectae (House) D. F. Austin, but retain his usage pending further studies.

Infrageneric taxa recognized within the American Ipomoea and the number of currently known species within each are summarized here. Of the 342 taxa recognized, only 10 are unplaced to subgenus.

subg. Eriospermum (Hallier f.) Verdcourt ex Austin

sect. Eriospermum Hallier f.

ser. Eriospermum (Hallier f.) D. F. Austin (=Dactylophyllae (House) D. F. Austin; = 'Microsticta' group of McPherson) (64 taxa)

ser. Anisomeres (House) D. F. Austin (3 species)

ser. Arborescentes (Choisy) D. F. Austin (12 taxa)

ser. Batatas (Choisy) D. F. Austin, Taxon 45:3-38. 1996. Basionym: subg. Quamoclit (Moench) Clarke sect. Batatas (Choisy) Grisebach, Fl. Brit. W. Ind. Isl. 469. 1869 (15 taxa)

ser. Bombycospermum (Presl) D. F. Austin (1 species)

ser. Jalapae (House) D. F. Austin (35 species)

ser. Mirandinae D. F. Austin (7 species)

ser. Setosae (House) D. F. Austin (7 species)

ser. ? (59 species)

sect. Erpipomoea Choisy (9 species)

subg. ?Eriospermum

sect. ?, ser. ? (16 species)

subg. Ipomoea L.

sect. Pharbitis (Choisy) Grisebach

ser. Pharbitis (Choisy) D. F. Austin (10 species)

ser. Heterophyllae (House) D. F. Austin (10 species)

ser. Tyrianthinae (House) D. F. Austin (10 species)

subg. Quamoclit (Moench) Clarke

sect. Calonyction (Choisy) Grisebach (4 species)

sect. Exogonium (Choisy) Grisebach (24 taxa)

sect. 'Microsepalae' (2 species)

sect. Mina (Cervantes.) Grisebach (18 species)

sect. Leptocallis (G. Don) J. A. McDonald (= ser. Pedatisectae (House) D. F. Austin)

(14 taxa)

sect. Tricolores (7 species)

subg. Quamoclit

sect. ? (7 species)

The country abbreviations used to indicate the geographic distribution of each species (Table 2) are those recommended by the United Nations (Anonymous, 1988). Full geographical designations are sometimes used when a given species is found in some states or regions that are isolated from their main territory, e.g., Hawaii, Galapagos, Lesser Antilles. Our geographic range records are based on specimens we have examined or those cited by other authors. Species have been reported from several places that we have not listed because no voucher was cited.

The species that have been examined in the past five decades by long-term students of the American taxa are listed alphabetically in Table 1. Most infraspecific names have been excluded; selected taxa are included to draw attention to what we consider unusual situations. Several previous authors have, in our opinion, created far too many such names. Synonyms are cross-referenced to the accepted names (Table 3).

Placement of the species in the various generic subdivisions results from a combination of literature survey and personal study. For example, O'Donell (1959) was followed for Ipomoea sect. Mina, with additions (as I. sect. Quamoclit) by Eckenwalder (1989) and McDonald (1991). For some species the placement has been changed from McPherson's (1979), but many of his suggestions have been adopted. McDonald (1991) placed most of the Mexican species; a few of those he included among 'Species Inquirendae' have been studied and can now be placed (Austin, 1991a; McDonald & Mabry, 1992).

Those species that are unplaced typically represent taxa for which insufficient material is available. Some are clearly distinct from anything else known, but specimens do not have critical stages for infrageneric placement (e.g., no fruits or buds are known for Ipomoea alexandrae or I. chodatiana). The majority of the unplaced species are rare; many are local endemics. We know that some of the endemic taxa are endangered--e.g., most of the Caribbean endemics such as I. sphenophylla (Howard & McDonald, 1995); also MesoAmerican I. tabascana (Austin & al., 1991a), and South American I. peruviana (Díaz & al., 1991), I. cavelcantei (Austin, 1981), I. carajasense (Austin & Secco, 1988)--and suspect that a large number of the others are so too.

This compilation should in no way be construed as a list of all the Ipomoea species in the Americas. Our second list (Table 3) contains 150 binomials that either have not been verified, or we cannot place with confidence. Of these, Wilkin (pers. comm., 1995) will be including about 50 species, mostly from Brazil and Paraguay, in his forthcoming study.

A prime example of incomplete knowledge of Ipomoea occurs in Brazil. In the late 1970s the first author compiled data on every binomial that had been applied to Brazilian species; since then thousands of specimens from that country have been sent to him for determination. Many of the names available are of questionable usage in the Planalto and Nordeste of Brazil; a number of the specimens match none of the named species and represent undescribed ones. Several Brazilian researchers are now studying the plants of their country and hopefully we will have better information on this region of high biodiversity in the next few years.

Acknowledgments

This study was partly supported by USAID/USDA (Grant No. 59-319R-4-011) to both authors, and by the National Geographic Society (Grant No. 4478-91 to D.F.A.) for field work in Costa Rica and Mexico. Publication was funded by the Centro Internacional de la Papa (CIP), Lima, Peru. We thank S. K. Austin (Boca Raton), Sebsebe Demissew (Addis Abeba), A. McDonald (Harvard), Bernard Verdcourt (Kew) and Paul Wilkin (Kew) for comments.

Literature cited

Anonymous. 1988. International standard codes for the representation of names of countries, ed. 3. Geneva.

Austin, D. F. 1975a. Typification of the New World subdivisions of Ipomoea. Taxon 24: 107-110.

_____. 1975b. Convolvulaceae [In: Flora of Panama]. Ann. Missouri Bot. Gard. 62: 147-224.

_____. 1978. The Ipomoea batatas complexÐ I. Taxonomy. Bull. Torrey Bot. Club 105: 114-129.

_____. 1979. An infrageneric classification for Ipomoea (Convolvulaceae). Taxon 28: 359-361.

_____. 1980a. Convolvulaceae Pp. 288-363 in: Dassenayake, M. D. & Fosberg, F. R. (ed.). A revised handbook of the flora of Ceylon. 1. New Delh I.

_____. 1980b. Additional comments on infrageneric taxa in Ipomoea (Convolvulaceae). Taxon 29: 501-502.

_____. 1981. Novidades na flora Amazônica. Acta Amazônica 11: 291-295.

_____. 1982a. Convolvulaceae, Family 165. in: Harling, G. & Sparre, B. (ed.). Flora of Ecuador 15. Stockholm.

_____. 1982b. Convolvulaceae Pp. 15-226 in: Luces de Febres, Z. & Steyermark, J. A. (ed.). Flora de Venezuela 8(3). Caracas.

_____. 1982c. Convolvulaceae Pp. 1161-1191 in: Correll, D. S. & Correll, H. B. Flora of the Bahama Archipelago. Vaduz.

_____. 1985. Los camotes silvestres y cultivados del Perú: Ipomoea spp. (Convolvulaceae). Bol. Lima 41: 29-38.

_____. 1986. Convolvulaceae Pp. 652-661 in: Barkley, T. (ed.). Flora of the Great Plains. Lawrence.

_____. 1990. Annotated checklist of New Mexican Convolvulaceae. Sida 14: 273-286.

_____. 1991a. Annotated checklist of Arizona Convolvulaceae. Sida 14: 443-457.

_____. 1991b. Ipomoea littoralis (Convolvulaceae): taxonomy, distribution and ethnobotany. Econ. Bot. 45: 251-256.

_____ & Cavalcante, P. B. 1982. Convolvuláceas de Amazônia. Museu Emilio Goeldi, Publicaciones Avulsas No. 36. Belém.

_____, Huáman, Z. & Puente, F. de la. 1986. Especies adicionales del genero Ipomoea (Convolvulaceae) en el Peru. Bol. Lima 47: 91-96.

_____ & Secco, R. de S. 1988. Ipomoea carajasensis, nova Convolvulacea da Serra dos Carajas (PA). Bol. Museu Paraense Emilio Goeldi 4: 187-194.

_____ & Staples, G. W. 1991. A revision of the neotropical species of Turbina Raf. (Convolvulaceae). Bull. Torrey Bot. Club 118: 265-280.

_____, Jansson, R. K. & Wolfe, G. W. 1991a. Convolvulaceae and Cylas: a proposed hypothesis on the origins of this plant: insect relationship. Trop. Agric. 68: 162-170.

_____, Puente, F. de la & Contreras, J. 1991b. Ipomoea tabascana, an endangered tropical species. Econ. Bot. 45: 435.

_____ & Wilkin, P. 1993. Realignment of Ipomoea peruviana (Convolvulaceae). Econ. Bot. 47: 206-207.

Choisy, J. 1845. Convolvulaceae Pp. 323-465 in: Candolle, A. L. P. P. de (ed.). Prodromus systematis naturalis regni vegetabilis 9. Paris.

Deroin, T. 1992. Espèces nouvelles de Convolvulaceae du Sud de Madagascar. Bull. Mus. Natl. Hist. Nat. Paris 4e ser. 14 section B, Adansonia: 335-346.

Díaz, J., Puente, F. de la & Austin, D. F. 1991. Barrio Berlin: ecological niche of Ipomoea peruviana (Convolvulaceae) in Peru. Econ. Bot. 45: 521.

Eckenwalder, J. E. 1989. A new species of Ipomoea section Quamoclit (Convolvulaceae) from the Caribbean and a new combination for a Mexican species. Brittonia 41: 75-79.

Gonçalves, M. L. 1987. Convolvulaceae and Cuscutaceae. Flora Zambesiaca. London.

Greuter, W., Barrie, F. F., Burdet, H. M., Chaloner, W. G., Demoulin, V., Hawksworth, D. L., Jørgensen, P. M., Nicolson, D. H., Silva, P.C., Trehane, P., McNeill, J. (ed.). 1994. International Code of Botanical Nomenclature. Regnum Veg. 131.

Heine, H. 1984. Convolvulaceae. In: Flore de la Nouvelle-Calédonie et dépendances. Paris.

House, H. D. 1908a. Studies in the North American ConvolvulaceaeÐIV. The genus Exogonium. Bull. Torrey Bot. Club 35: 97-107.

_____. 1908b. The North American species of the genus Ipomoea. Ann. New York Acad. Sc I. 18: 181-263.

Howard, R. A. & J. A. McDonald. 1995. Ipomoea sphenophylla Urban recollected and neotypified. Harvard Pap. 7: 69-72.

Mabberley, D. J. 1989. The plant-book. ed. 2. Cambridge.

McDonald, J. A. 1978. Systematics and uses of the genus Ipomoea (Convolvulaceae) of Oaxaca, Mexico. unpublished thesis, Blacksburg, Virginia.

_____. 1982a. A new species of Ipomoea (Convolvulaceae) from southwestern Mexico. Brittonia 34: 336-338.

_____. 1982b. Biosystematics of the Ipomoea tricolor complex (Convolvulaceae). unpublished Ph.D. dissertation, University of Texas, Austin.

_____. 1987a. Notas del herbário XAL. X. Tres especies nuevas de Convolvulaceae para México. Biotica 12: 217-224.

_____. 1987b. Three new species of Convolvulaceae from northeast Mexico. Brittonia 39: 106-111.

_____. 1987c. Revision of Ipomoea sect. Exogonium (Convolvulaceae). Brenesia 8: 41-87.

_____. 1989. Neotypification of Ipomoea jalapa (Convolvulaceae). Taxon 38: 135-138.

_____. 1991. Origin and diversity of Mexican Convolvulaceae. Anal. Inst. Biol. Univ. Nac. Autón. México, Ser. Bot. 62: 65-82.

_____. 1992. A new species of Ipomoea (Convolvulaceae) from Oaxaca, Mexico. Sida 15: 173-175.

_____. 1993a. A new species of Ipomoea (Convolvulaceae) from Costa Rica and notes on the circumscription of section Calonyction (Choisy) Griseb. Harvard Pap. 4: 53-56.

_____. 1993b. A new species, name change, and association for Ipomoea section Mina (Cerv.) Griseb. (Convolvulaceae). Harvard Pap. 4: 49-52.

_____. 1995. Revision of Ipomoea section Leptocallis (Convolvulaceae). Harvard Pap. 6: 97-122.

_____ & Austin, D. F. 1990. Additions and changes in Ipomoea section Batatas (Convolvulaceae). Brittonia 42: 116-120.

_____ & Mabry, T. J. 1992. Phylogenetic systematics of New World Ipomoea (Convolvulaceae) based on chloroplast DNA restriction site variation. Pl. Syst. Evol. 180: 243-259.

McPherson, G. D. 1979. Studies in the genus Ipomoea (Convolvulaceae). unpublished Ph.D. dissertation, University of Michigan, Ann Arbor.

_____ . 1980. Eight new species of Ipomoea and Quamoclit from Mexico. Contr. Univ. Mich. Herb. 14: 85-97.

_____ . 1981. Studies in Ipomoea (Convolvulaceae) I. The Arborescens group. Ann. Missouri Bot. Gard. 68: 527-545.

_____ . 1993. Convolvulaceae [In: Brako, L. & Zarucchi, J. L. Catalogue of the flowering plants and gymnosperms of Peru/Catálogo de las angiospermas y gimnospermas del Perú]. Monogr. Syst. Bot. 45: 365-374.

Mandrile, E. L. & Dongiorno de Pfirter, G. 1990. Principios activos naturales con acción alucinógena. VII I. Alacaloides derivados de la ergolina. Acta Farmacol. Bonaerense 9: 41-52.

Matuda, E. 1963. El genera Ipomoea en México- I. Anales Inst. Biol. Mex. 34:85-145.

_____. 1964(1965). El genera Ipomoea en México (II). Anales Inst. Biol. Mex. 35: 45-76.

_____. 1965. El genera Ipomoea en México (III). Anales Inst. Biol. Mex. 36: 83-106.

_____. 1966. Las Convolvuláceas del estado de México. Toluca.

Meeuse, A. D. J. 1957. The South African Convolvulaceae. Bothalia 6: 641-792.

Meisner, C. F. 1869. Convolvulaceae Pp. 200-424 in: Martius, C. (ed.). Flora brasiliensis 7. Vienna.

O'Donell, C. A. 1941. Convolvuláceas mexicanas. Anales Inst. Biol. Mex. 12: 91.95.

_____ . 1948a. Convolvuláceas argentinas y paraguayas nuevas o críticas. Lilloa 14: 169-192.

_____ . 1948b. Convolvuláceas Peruanas nuevas. Bol. Soc. Peruviana Bot. 1: 4.7.

_____ . 1950a. Convolvuláceas americanas nuevas o críticas I. Lilloa 23: 421-456.

_____ . 1950b. Convolvuláceas americanas nuevas o críticas I I. Lilloa 23: 457-508.

_____ . 1950c. Una nueva convolvulácea brasileña. Dusenia 1: 375-376.

_____ . 1952a. Convolvuláceas americanas nuevas o críticas II I. Arq. Museu Paranaense Curitiba 9: 207-244.

_____ . 1952b. Convolvuláceas brasileñas nuevas. Dusenia 3: 274-282.

_____ . 1953a. Convolvuláceas americanas nuevas o críticas IV. Lilloa 26: 353-400.

_____ . 1953b. Una nueva Convolvulaceae sudamericana. Bol. Soc. Argentina Bot. 4: 260.

_____ . 1957. Convolvuloideas Chilenas. Bol. Soc. Argentina Bot. 6: 143-184.

_____ . 1959a. Convolvuláceas argentinas. Lilloa 29: 87-343.

_____ . 1959b. Convolvuloideas de Uruguay. Lilloa 29: 349-376.

_____ . 1959c. Las especies americanas de Ipomoea L. sect. Quamoclit (Moench) Griseb. Lilloa 29: 19-86.

_____ . 1960a. Convolvuláceas argentinas I I. Lilloa 30: 5-38.

_____ . 1960b. Notas sobre Convolvuláceas americanas. Lilloa 30: 39-69.

Ooststroom, S. J. van. 1953. Convolvulaceae Pp. 388-512 in: Steenis, C. G. G. J. van (ed.). Flora Malesiana, ser. 1, 4(4). Djakarta.

Pedraza, R. A. 1983. Estudio palinológico de la familia Convolvulaceae en México. I. Generos Ipomoea L. y Turbina Raf. Biotica 8: 387-411.

Stearn, W. T. 1977. Turbina corymbosa. Curtis's Bot. Mag. 181: 59-56.

Verdcourt, B. 1957. Typification of the subdivisions of Ipomoea L. (Convolvulaceae) with particular regard to the East African species. Taxon 6: 150-152.

_____ . 1958. Some notes on tropical African Convolvulaceae. Webbia 13: 321-330.

_____ . 1963. Convolvulaceae In: Hubbard, Milne-Redhead, C. E. & E. (eds.). Flora of Tropical East Africa. London.

Wilkin, P. 1995. A new species of Ipomoea (Convolvulaceae) from Mexico State, Mexico, and its evolution. Kew Bulletin 50: 93-102.

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