Revision of Dieffenbachia (Araceae) of Mexico, Central America, and The
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REVISION OF Thomas B. Croat2 DIEFFENBACHIA (ARACEAE) OF MEXICO, CENTRAL AMERICA, AND THE WEST INDIES1 ABSTRACT The genus Dieffenbachia Schott has approximately 135 species, most of them occurring in South America. Major centers of diversity for the genus include Colombia with 37 species, Ecuador (34), Peru (30), Brazil (27), Panama (20), and Costa Rica (13). There are 26 species in Central America, with 20 species (77%) new to science. These are D. burgeri Croat & Grayum, D. copensis Croat, D. crebripistillata Croat, D. davidsei Croat & Grayum, D. fortunensis Croat, D. fosteri Croat, D. galdamesiae Croat, D. horichii Croat & Grayum, D. isthmia Croat, D. killipii Croat, D. lutheri Croat, D. nitidipetiolata Croat, D. obscurinervia Croat, D. panamensis Croat, and D. standleyi Croat described herein and D. beachiana Croat & Grayum, D. concinna Croat & Grayum, D. grayumii Croat, D. hammelii Croat & Grayum, and D. tonduzii Croat & Grayum described elsewhere. Most species range from Nicaragua to Panama. Belize has only 1 species of Dieffenbachia; Mexico, El Salvador, and Guatemala have 2 species, followed by Honduras (3), Nicaragua (6), Costa Rica (13), and Panama (20). Only a few Central American species could be considered widespread. Among the most widespread are D. oerstedii Schott and D. wendlandii Schott, both of which range from Mexico to Panama, as well as D. nitidipetiolata and D. tonduzii, which range from Honduras to Ecuador. Species endemism is high, especially in Costa Rica (3) and Panama (9). A total of 9 species are shared between Panama and Costa Rica. Eight species, almost 31% of the total, range into South America. These are D. davidsei, D. isthmia, D. killipii, D. longispatha, D. nitidipe- tiolata, D. obscurinervia, D. seguine, and D. tonduzii. Most of these only extend to Colombia, but three species, D. killipii, D. nitidipetiolata, and D. tonduzii, range to Ecuador. Only D. killipii ranges to the eastern slope of the Andes. Dieffenbachia seguine ranges into Brazil and Bolivia, from the West Indies. Key words: Araceae, Central America, Dieffenbachia, Mexico, South America, West Indies. The family Araceae is worldwide in distribution, Schott ex K. Krause). Important local centers of but most species occur in tropical areas. Its centers generic endemism in the family include Brazil, of distribution include both Asia and America which has four endemic genera (Bognera Mayo & (Croat, 1979), with 31 genera in the Americas and Nicolson, Dracontioides Engl., Gearum N. E. Br., 28 found in Asia. There are 16 genera in Africa, Zomicarpa Schott), and the Indomalaysian region, Madagascar, and the Seychelles. A few genera are with 14 endemic genera. At least 2550 species, restricted to temperate regions of the Northern representing four-®fths of the total, occur in the Hemisphere, including the Mediterranean region Neotropics. The Central American ¯ora comprises (Calla L., Lysichiton Schott, Orontium L., Peltandra 19 genera within the Araceae. Raf., Symplocarpus Salisb. ex Nutt.), including the With an estimate of more than 2550 species in Mediterranean region (Arisarum Mill., Ambrosina Latin America, the Araceae are one of the largest Bassi, Arum L., Dracunculus Mill., Helicodiceros families of ¯owering plants in the region. Yet no 1 This revision could not have been completed without the dedicated and able assistance of my former co-worker, Petra Schmidt, who participated in nearly every phase of the work. She continued the research efforts unabated while I was in the ®eld. Monica Carlsen and Emily Yates, former and present Research Assistants, respectively, were re- sponsible for ®nal editing and revision of the manuscript, including ®nal preparation of legend images. Fred Keusen- kothen was responsible for preparation of scanned images. Special thanks also must go to Cheryl Neuman and Emily Colletti, Research Greenhouse managers during the course of this work, who maintained hundreds of Dieffenbachia collections in healthy condition. Very special thanks also go to my colleague and fellow aroid specialist Mike Grayum, whose knowledge of the Costa Rican Araceae is unparalleled. Dan Nicolson, from the U.S. National Herbarium, and Charlotte Taylor, MO, assisted with nomenclatural issues. John Rawlins, from the Carnegie Museum, Pittsburgh, de- termined most of the beetles collected for this revision of Dieffenbachia. Thanks also go to Helen Young for beetle determinations and for information on reproductive biology. Elenor Sauer has proofread or written Latin diagnoses for all of the new species. Her expert assistance is greatly appreciated. Finally, I would like to thank my wife, Patricia, who has put up with my long absences while doing ®eldwork for more than three decades. She was always available as an editor and to solve computer and database problems. 2 P. A. Schulze, Curator of Botany, Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166-0299, U.S.A. ANN.MISSOURI BOT.GARD. 91: 668±772. 2004. Volume 91, Number 4 Croat 669 2004 Revision of Dieffenbachia other family is so poorly known taxonomically. with the lowest totals just north of the San Juan Plants exhibit considerable morphological plasticity depression (Nicaragua), followed by a marked in- at all stages of development. Many of the genera, crease approaching the South American continent. especially the hemiepiphytic genera Rhodospatha (In this treatment, Central America is de®ned as all Poepp., Monstera Adans., and Syngonium Schott, the area between Mexico and Colombia, whereas exhibit complex patterns of heterophylly, with dras- Middle America is all the area between Mexico and tically different morphology at different stages of Panama.) Mexico has 2 species, Guatemala (2), Be- development (Croat, 1981 [1982]; Ray, 1981, lize (1), Honduras (3), El Salvador (2), Nicaragua 1987). Most members of the family have succulent (6), Costa Rica (13), and Panama (20) (Table 1). parts, making them dif®cult to collect and preserve. Endemism is high, especially in Costa Rica with 3 Dieffenbachia is one of several medium-sized endemic species and Panama with 9. A total of 7 genera in the Araceae, with an estimated 135 spe- species are shared between Panama and Costa cies. This revision is the ®rst major review of Dief- Rica. Just under one-third (31%) of Central Amer- fenbachia for Central America since Adolf Engler's ican species of Dieffenbachia range into South (1915) generic treatment in Das P¯anzenreich. America, these being D. davidsei, D. isthmia, D. Dieffenbachia is one of the most important genera killipii, D. longispatha, D. nitidipetiolata, D. obscu- of understory herbs in the family, and it is often a rinervia, D. seguine, and D. tonduzii. dominant component of humid to wet tropical for- ests, especially from sea level to 1500 m. It inhab- MATERIALS AND METHODS its life zones ranging through Premontane moist for- est (P-mf), Tropical moist forest (T-mf), Premontane This revision is based on more than 29 years of wet forest (P-wf), Tropical wet forest (T-wf), and Pre- ®eld studies in Central and South America, be- montane rain forest (P-rf) (Holdridge, 1967). While tween 1967 and 1996. All but one species were most species occur in virgin humid forests, the ge- studied live in the ®eld or under cultivation at the nus is known from freshwater swamps, stream Missouri Botanical Garden. The descriptions have banks, regrowth forest, among rock outcrops, and been prepared from both living and dried speci- occasionally on road banks. It often constitutes the mens. The exception is D. fosteri, where the de- most conspicuous element of the understory vege- scription was based solely on the type specimen. tation because of its abundance, frequent colonial The use of (``dried'') preceding all or any part of growth habit, and generally large, showy leaves. the description is an indication that all that follows The genus provides a wide variety of choice orna- is based on herbarium material only. Morphological mental plants for horticulture, including most of the characters were coded directly into a computerized species treated here. database to ensure parallel and sortable descrip- The genus is distinct and not easily confused tions. The aroid descriptions database contains 784 with any other aroid. It is closest to Bognera, which character states applicable to the morphological di- differs in lacking staminodia surrounding the pis- versity expressed in Dieffenbachia (Croat, 1997). tillate ¯owers and in having higher-order venation Discussions and references to illustrations, as well reticulate. In contrast, Dieffenbachia has several as exsiccatae, are stored separately, but tied to a staminodia surrounding the pistils and higher-order particular species description and to the nomencla- venation parallel-pinnate. However, the monotypic tural information by a unique taxon number. Ter- genus Bognera is endemic to Brazil, and it is not minology and usage in the descriptions in this re- likely to be a problem with determination of most vision are largely de®ned by Croat and Bunting Dieffenbachia. Alternatively, Dieffenbachia is fre- (1979) and elaborated in Croat (1997). quently confused with Philodendron Schott, partic- Ecological zones, though sometimes estimated ularly the terrestrial species of the latter with non- from my own experience with Central American cordate blades. Philodendron species are mostly vegetation, are largely taken from Holdridge life- hemiepiphytic, rarely terrestrial as is Dieffenbachia. zone maps (Holdridge, 1967; Holdridge et al., Even when Philodendron species are terrestrial and 1971), where they exist for Central American coun- have non-cordate blades, they can be distinguished tries, and for Mexico from the ``Mapa de tipos de by the remotely many-¯owered pistils that are not vegetacioÂn de la RepuÂblica de MeÂxico'' (Flores et surrounded by staminodia, as well as the lack of al., 1971). the acrid foul-smelling, irritating sap that is so Herbarium material has been widely distributed closely associated with Dieffenbachia. and original ®eld vouchers are cited for all herbaria Species diversity of Dieffenbachia shows a gen- whose material was seen (see Appendices 1, 2).