From Plant Press, Vol. 4, No. 1 from January 2001.
By Robert DeFilipps
Let us assemble in a spirit of forgiveness, as we review the case of Henry Fletcher Hance (1827-1886), the legendary British botanist in Hong Kong and later consul in Whampoa, Amoy and Canton, who could not have foreseen the great mystery that would arise from his choice of “Rhoeo” as the name of a new genus of Mexican Commelinaceae. To this day the derivation of Rhoeo is cited in botanical reference books as either unknown or obscure. Yet this plant, with purple boat-shaped inflorescence bracts enclosing slightly emergent white flowers, is well known in the vernacular of gardeners and houseplant enthusiasts as the “boat-lily”, “oyster plant”, “Moses-in-a-boat” or “three-men-in-a-boat”.
From E.H.M. Cox’s book on “Plant-Hunting in China” (1945), we learn that Hance “was an expert linguist, completely word perfect in Latin, Greek, French and German.” Inspired by that clue, a search of worldwide websites led me to Peter Hawlina, a professional genealogist residing in Slovenia, who provided an answer to Hance’s puzzle. It transpires that Rhoeo is a Greek mythological figure, the daughter of Staphylos (father) and Chrysothemis (mother), and she was a mistress of the god Zeus. Staphylos became angry when he found out Rhoeo was pregnant, and locked her in a chest and put it in the sea. The chest later washed up on the coast of Euboea (or Delos), after which Rhoeo gave birth to a son, Anius. The “Encyclopedia Mythica” notes that Anius was the father of three daughters: Oeno (wine), Spermo (grain seed) and Elais (oil), who were given the power to generate those crops.
For someone as erudite in Greek as Henry Hance in the 1800s, it would have been appropriate to bestow the name “Rhoeo” on a plant with boat-like bracts enclosing a seemingly hidden inflorescence, to commemorate the mythological Rhoeo’s claustrophobic maritime predicament in the Mediterranean Sea. The boat-lily, long known as Rhoeo spathacea, is currently referable to Tradescantia spathacea, while Rhoeo herself lives on as Tradescantia Section Rhoeo (Hance) D.R. Hunt.
Mexico and Central America, the home of the boat-lily, is along with continental Asia and tropical Africa a center of diversity of the mainly tropical and warm temperate monocot family Commelinaceae, comprised of approximately 41 genera and 650 species. The family is a major research specialty of Robert B. Faden, curator of African plants in the Department. A native of the Bronx, New York, he earned a B.S. cum laude (1962)from City College of New York; M.S. (1964) from the University of Michigan; and a Ph.D. in Biology (1975) from Washington University, St. Louis. After a period of time (1976-1980) as curator of botany at the Field Museum of Natural History in Chicago, Illinois, he arrived at the Smithsonian Institution to take up duties as curator in 1980.
It is rather unusual for a taxonomist to have an abiding interest in ferns as well as flowering plants, and Faden has amply demonstrated an expertise in both groups, while naming a new species of cycad with H.J. Beentje (Encephalartos kisambo) to round out the whole gemisch. Faden’s fern research began as an undergraduate in New York with an honors thesis on the ferns of New York City and a paper on Staten Island pteridophytes (1962), and continued with his treatment of some 200 tropical East African fern species in Upland Kenya Wild Flowers (by A. Agnew & S. Agnew, 1994). In a review of the first edition of the latter (Agnew 1974), B. Verdcourt (Kew Bull. 30:422. 1975) noted that Faden's treatment was "no mere compilation" but was based on intensive collecting. He referred to Faden's "fantastic habit of turning up exciting new plants in well-known areas" as "smack[ing] almost of wizardry." Five species of ferns (as well as an epiphyllous lichen and liverwort) now bear the epithet “fadenii” as a result of his field collections.
From graduate school in Michigan, Faden joined the Peace Corps and was based at Thika near Nairobi, Kenya, where he taught biology for three years and was encouraged to collect plants for the East African Herbarium in Nairobi. Many of his specimens were also sent to the Herbarium of the Royal Botanic Gardens, Kew, an institution with which he continues to maintain a close working relationship.
In Kenya, Faden found new national records for the genus Baphia, a leguminous tree, the verbenaceous genus Karomia (first described as Holmskioldia), and many other genera and species. Eventually, Andrew Agnew of the University of Nairobi invited him to undertake a treatment of the abundant Kenyan Commelinaceae for Agnew’s book on Kenya wildflowers. This he did, and from it followed numerous other studies of Commelinaceae on a worldwide basis over the years, including publications in Flora of North America (to which he also contributed Mayacaceae), and the floras of Ecuador, Ethiopia, Equatorial Guinea, Sri Lanka, Somalia and Southern Africa.
Faden has performed fieldwork in a large array of countries, much of it with his wife Audrey, including the United States, Mexico, Costa Rica, India, Pakistan, Sri Lanka, and 11 African nations from Cameroon and Ghana to Somalia, Uganda, Zimbabwe, Zambia and beyond. Attesting to his remarkable “eye” for spotting novelties during field collecting trips are 12 Kenyan angiosperm species named in his honor by specialists, including new members of the families Dichapetalaceae, Euphorbiaceae, Rubiaceae (such as Coffea fadenii), Rutaceae, Urticaceae, Amaranthaceae, Capparaceae and Crassulaceae. They are crowned, as it were, by the genus Fadenia Aellen & C.C. Townsend (Chenopodiaceae), although Faden once wrote: “I maintain that Audrey was the best collection that I ever made in Africa!” Kenya-born Audrey Faden is a landscaper, master gardener and Smithsonian volunteer for the intensive cultivation and maintenance of numerous commelinads used for research, growing in the departmental greenhouse in Silver Hill, Maryland. Both people are also intensely involved with the Potomac Valley Chapter of the North American Rock Garden Society.
Commelinaceae is the family of the bright blue dayflower (Commelina), the wandering Jew and the purple heart (both Tradescantia). A number of tribal and subtribal realignments in this family have been made by Faden and D.R. Hunt. In addition to the type genus Commelina, several mostly Asiatic and African genera have become subjects of intense research and sources of newly described species for Faden, including Murdannia, Aneilema, Palisota, and Pollia. But that is not to suggest that all is known about this family. At the moment, he is finishing a treatment of Commelinaceae for the Flora of the Guianas, and is continuing work on accounts for the Flora of Tropical East Africa, Flora Zambesiaca and Flore du Cameroun, while studying generic relationships by cladistic methods (with Tim Evans and others) and developing a database on leaf anatomical characteristics from a family survey.
His carefully cultivated greenhouse plants, derived from populations around the world, are used at various junctures for studies of floral morphology, phenology patterns in species with dimorphic (bisexual and male) flowers, chromosome counts, DNA sequencing (with Tim Evans), seed germination, and occasionally as parent material for hybrid crosses. Faden has performed the cross of Tradescantia pallida ‘Purple Heart’ x Tradescantia buckleyi (from Texas-Mexico) in both directions. The extent of natural hybridization in the family remains a large question to be probed by all interested researchers.
More fieldwork and collections of living material will follow. We might hope that perhaps some of Faden’s future studies could involve medicinal plants, encouraged by the fact that a remedy for children’s eye infections using the spathe-liquid of Commelina, which was originally recorded by someone from Bolivia, was independently noted by Faden in use in Tanzania; absence of calcium oxalate crystals in the spathe-liquid make it soothing in contrast to the crystal-bearing liquid found in other tissues of the plant. Strangely enough, reports from the fairly new (to botanists) discipline of zoopharmacognosy indicate that in Tanzania and the Democratic Republic of the Congo, chimpanzees and eastern lowland gorillas, respectively, seek out and consume leaves of Commelina, likely for reasons of health or digestive improvement (Sumner, J. 2000. The Natural History of Medicinal Plants).
Africa will remain a significant focus of Faden’s work in the coming years, for he has observed that approximately three-quarters of Kenya is too dry for agriculture, and 90 percent of that area is still poorly known botanically, with most species, including many annuals and bulbous plants, coming into flower only during the rains. Preparation of a basic flora of the Mpala Research Station in Kenya, which he was involved in setting up for research, would also be a good project for this omnivorous collector.
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