Future Research Needs

The following summary of the taxonomic needs, in so far as they pertain to the neotropics, is a synopsis of a more extensive analysis entitled "Taxonomic status of Neotropical Araceae" (Croat,1994c).

The Araceae are not equally distributed throughout the world, being much more abundant in tropical areas. There are two major centers of species diversity, tropical Asia, with 44 indigenous genera, and tropical America, with 36 (Croat, 1979b). Of these, 33 (75%) are endemic to the American tropics and 32 (89%) are endemic to Asia. Africa, a less important center of species diversity, has only 19 indigenous genera of which 12 (63%) of them endemic.

Research with Araceae is also quite unequal on a worldwide basis. It has, for obvious reasons, been most intense in temperate areas, especially in North America, Europe and Japan because most work has been done by Europeans, Americans, or Japanese, respectively.

If, as expected, the current work with the Flora Malesiana project results in regional treatments of such large genera as Amorphophallus, Homalomena, Pothos, Rhaphidophora, and Schismatoglottis, the obvious priority for Asia would be to continue these studies to include India and other areas of Asia so that complete monographic revisions could be completed. Hetterscheid will independently complete his revision of Amorphophallus within the next few years. The balance of Asia, which includes such complex genera as Aglaonema (already revised once by Dan Nicolson [Nicolson, 1969]) Alocasia, Arisaema, Homalomena, Pothos, Rhaphidophora, Scindapsus, and Schismatoglottis, should prove no obstacle for the Flora Malesiana team now assembled. The revision of the Araceae for the Flora of China by Li Heng, Jin Murata, and perhaps others is opportune, given the strong impetus of the Flora Malesiana project. There are areas where more field work would be welcome, such as in Vietnam, Laos, Cambodia and especially Myanmar; areas long closed to most of the world's botanists, the latter two countries still closed today. Work in India (by M. Sivadasan) and Vietnam (Nguyen, Boyce, and Serebryanyi) is in preparation. Still, it seems logical that the Araceae of Asia and the mostly related continent of Australia might become quite well known within the next 25 years. Australia was thought to be well known until A. Hay discovered a batch of new species and a genus new to Asia. Described as the new genus Lazarum, Hay now believes it to be a new species of Typhonium (Hay, 1997b).

Africa is a lesser center of species diversity than Asia as noted above but many of the genera have only a few species and none are large. This should make the taxonomy of the area less complicated. Considerable floristic work took place in Africa in earlier colonial times but less floristic and monographic work is being done today with Araceae. Much of the continent is now relatively well known floristically, thanks to a modern revision of Tropical East Africa (Mayo, 1985a) and Madagascar (Bogner, 1972a, 1972b, 1973a, 1973b, 1975). However, there still are areas which need to be further explored, especially in Cameroon, Gabon, Central African Republic, and Congo (formerly Zaire). Except for the genus Culcasia, which is complex, fairly species-rich and in need of a modern revision, the continent of Africa by no means poses serious taxonomic problems for Araceae (Hepper, 1967).

Stephan Ittenbach, from the University of Bonn, under the supervision of Wolfram Lobin, has completed an as yet unpublished revision of the African species of Amorphophallus. Anubias has recently been revised (Crusio, 1979a, 1987; de Wit, 1990) and much of the genus Stylochaeton occurs in the region of the Flora of Tropical East Africa. A thorough study of the Araceae of the Ivory Coast (Knecht, 1983), a part of Tropical West Africa, appears to be relatively well known and well documented. This study, coupled with the relatively thorough revisions by Hepper (1968a) leave me with the impression that even a massive collecting program would not yield much new information to science.

The flora of Europe and the Near East is by now well known due to a variety of works including G. Hegi (Hegi, 1909, 1939) and the revision of this work by H. Riedl (Riedl, 1979) as well as the more recently published Blütenpflanzen Mitteleuropas (Aichele & Schwegler, 1996). Other efforts include Riedl's own work on the Flora of Iran and the Flora of Iraq in the Near East (Riedl, 1963, 1969, 1985), as well as works for Spain (Caballero, 1940); the Balkan Peninsula (Hayek, 1933); Iran (Assadi, 1989), Syria and Lebanon (Mouterde, 1966); Israel (Koach, 1988), a revision of Arum for the island of Crete (Greuter, 1984); the treatment for the Flora Europaea (Amaral Franco et al., 1980) and Peter Boyce's work with the studies of Mediterranean genera (Boyce 1994a, 1993a). Floristic work in Eastern Europe includes that of Russia (Kuzeneva, 1935) and Bulgaria (Kuzmanov, 1964).

Sue Thompson has revised the Araceae for the Flora of North America (Thompson, 2000). D. G. Huttleston (1953) earlier published a study of North American species. Monographic work on Arisaema for North America was done by Huttleston (Huttleston, 1953), and by Blackwell and Blackwell at Miami University (Blackwell & Blackwell, 1974), and by M. Treiber at the University of North Carolina (Treiber, 1980). Araceae of the region has been well studied in a wide range of regional floras or checklists, e.g. North America (Shetler & Skog, 1878; Kartesz & Kartesz, 1980); Canada (Marie-Victorin, 1931), Nova Scotia (Roland & Smith, 1069); northern U.S. and Canada (Britton & Brown, 1970; Lazarides et al., 1988); the Pacific Northwest (Hitchcock et al., 1969; Hitchcock & Cronquist, 1973); California (Jepson, 1925; Thomas, 1961; Hickman, 1993); Montana (Dorn, 1988a); Arizona (Kearney & Peebles, 1964); Colorado (Harrington, 1954); Wyoming (Dorn, 1988b); Great Plains (Rydberg, 1932; Churchill, 1986); North Dakota (Kannowski, 1989; Stevens, 1950); South Dakota (van Bruggen, 1985); Kansas (Barkley, 1968; Bare, 1979; Brooks, 1986; Stevens, 1961); Wisconsin (Judziewicz, 1993); Michigan (Voss, 1972); Missouri (Steyermark, 1963; Yatskievych & Turner, 1990; Dennison, 1978; St. Louis area (Eisendrath, 1978); Ozarks [Missouri] (Leake & Leake, 1989); Illinois (Mohlenbrock, 1975); Oklahoma (Waterfall, 1972); Arkansas (Hunter, 1988; Hyatt, 1993; Smith, 1994); Alabama (Diamond & Freeman, 1993); Texas (Gould, 1962; Correll & Johnston, 1979; Hatch et al., 1990); Mississippi (Fritsch, 1993; Lowe, 1921; Timme, 1989); the Carolinas (Radford, et al., 1968); eastern North America (Fernald, 1950; Leck & Simpson, 1993; Gleason & Cronquist, 1991; Stalter et al., 1993); Blue Ridge Mountains (Wofford, 1989; Ramsey et al., 1993); southeastern USA (Small, 1933; Wilson, 1960; Duncan & Foote, 1975); southwestern USA (Correll & Correll, 1972); tropical Florida (Long & Lakela, 1971); central Florida (Wunderlin, 1982), and the Florida Panhandle (Clewell, 1985). Hawaii, politically a part of the United States, has only introduced species (Croat, 1994c; Wagner et al., 1990).