News From MO: 2000
Thomas B. Croat, P. A. Schulze Curator of Botany, concentrates on the study of neotropical Araceae. Because of his efforts, the Missouri Botanical Garden has become a principal center of research in Araceae, with the largest collection of herbarium material and the most species-rich collection of living material in the world. A number of major revisions have been completed by Croat, including Anthurium and Philodendron for Central America, and complete revisions of Syngonium and Anthurium section Pachyneurium, all funded by the National Science Foundation. Floristic accounts for the Araceae have been completed for Nicaragua, Venezuela, Central French Guiana, Paraguay, Guyana, and Hawaii, and florulas have been prepared for several species-rich tropical areas, including La Planada (Nariño) and Bajo Calima (Valle) in Colombia. The latter florula project was funded by the National Geographic Society. In the summer of 2000 Croat collected with Marcela Mora in Cabo Corrientes, a remote, coastal region of Chocó Department in Colombia. He moved on to collect in the Lita-San Lorenzo area of Ecuador, for a project that is funded by the National Geographic Society. The last part of his collecting trip was to Bolivia, where he collected in the Yungas, Sapecho, and the Madidi National Park.
Revisions of the genera Rhodospatha and Dieffenbachia of Central America, both National Science Foundation-sponsored projects, are nearing completion. Floristic accounts are being prepared for Ecuador, Veracruz State of Mexico, and the Guyana region. Field work for a revision of Anthurium section Porphyrochitonium has already begun and, in collaboration with Richard Mansell (University of South Florida), work is progressing on a revision of Anthurium section Semaeophyllium. Other MO staff involved with Araceae include Michael Grayum, who has revised the Araceae for the Manual to the Plants of Costa Rica, as well as Philodendron subgenus Pteromischum, and Guanghua Zhu has revised Dracontium. Petra Malesevich coordinates the project work and manages various databases of Araceae. The living collection of more than 6,500 Araceae, managed by horticulturist Cheryl Neuman, along with its database, is the source of much new information on the biology and taxonomy of this diverse family.
Peter Goldblatt, Senior Curator and B. A. Krukoff Curator of African Botany, works largely on African plants and is a specialist on the systematics, biology, and phylogeny of the Iridaceae and related families of the petaloid monocots. His work is concentrated in southern Africa, an important center of evolution and diversification of petaloid monocots, including two-thirds of the estimated 1,800 species of Iridaceae. Goldblatt has completed systematic accounts of the Iridaceae for Flora Zambesiaca (100 species, 1993), Flora of Somalia (six species, 1995), Flora of Tropical East Africa (74 species, 1996), and for the Flora of Ethiopia (27 species, 1998). Working with J. C. Manning (National Botanic Institute, Kirstenbosch), Goldblatt has also completed a generic flora account for the Iridaceae of southern Africa now in press. Together Goldblatt and Manning have completed a comprehensive florula of the southern African winter-rainfall zone, the Cape flora region. This part of the southern African subcontinent has almost half the total species of vascular plants that occur in southern Africa, about 9,000 species, some 69% of them endemic. All of southern Africa, about ten times greater in area, has some 21,000 species. In the New World, Goldblatt has completed accounts of the Iridaceae for Flora Mesoamericana, Flora de Nicaragua, Manual to the Plants of Costa Rica, and Flora of the Venezuelan Guayana. These treatments were prepared with J. E. Henrich. An account of the Iridaceae for Flora of North America is now in preparation, and Goldblatt has contributed several genera of the family.
Goldblatt and Manning have an active research program, funded by the National Geographic Society, studying the pollination systems in the Iridaceae. They have completed studies of Lapeirousia (40 species) and southern African Gladiolus (165 species), both of which exhibit a wide range of pollination systems, including two novel systems involving different genera and species of long-proboscid flies in the horse fly (Tabanidae) and tangle-veined fly (Nemestrinidae) families of the Muscidae. These flies are the primary or sole pollinators of many species in both genera. The presence of these specialized pollinators and their associated guilds of plant species have permitted the diversification and radiation of species of several genera of Iridaceae, including into niches that apparently do not exist outside southern Africa. Goldblatt and Manning are also documenting several different guilds of plant species and their associated long-proboscid fly pollinators which have now been discovered across the entire southern African region. Three separate guilds of long-proboscid flies encompassing 14 species have been identified that are associated with different suites of plant species that occur in different parts of southern Africa or are active at different times of the years. The guilds invariably include two or more species of Iridaceae, often from different genera of the family, species of Pelargonium (Geraniaceae), and occasionally Amaryllidaceae, Orchidaceae, and Scrophulariaceae. Goldblatt and Manning are now extending their pollination studies to the genera Babiana, Hesperantha, Ixia, Romulea, and Sparaxis. The sub-Saharan African Hesperantha is particularly interesting, as different species exploit long-proboscid flies or settling moths for their pollination, the latter unique in the family, as well as nectar-foraging anthophorine bees, and scarab beetles.
Work on the systematics of the large genus Gladiolus was completed in 1998. A monograph of the genus in tropical Africa (83 species) was published by Goldblatt (Timber Press, 1996) and a second monograph, coauthored with Manning, dealt with 163 species in southern Africa. This work was released in 1998 (Fernwood Press, Cape Town) and included 144 sumptuous watercolor paintings. No sooner was the monograph published than two additional southern African endemics of the genus were discovered. Gladiolus has some 260 species, 250 in sub-Saharan Africa and Madagascar and 10 more in Eurasia. Southern Africa is the center of diversity of the genus and 160 of the 165 species that occur there are endemic, while tropical Africa has 76 endemic species of Gladiolus. The basic pollination system for the genus is one using long-tongued anthrophorine bees with nectar as a reward. Within the genus, frequent shifts in the pollination system have occurred, giving rise to pollination by sunbirds, noctuid and sphingid moths, long-tongued flies, a butterfly, and in a few instances, monkey beetles or short-tongued, pollen-collecting female bees. Comparison of the pollination systems with the infrageneric classification developed by Goldblatt and Manning suggests that at least 27 separate instances of a shift in pollinator have taken place. Goldblatt is working with Mark W. Chase (K), Paula Rudall (K), and Gail Reeves (K and NBG) on the generic phylogeny of the Iridaceae. DNA sequences of the chloroplast genes rbcL, rps4, and trnL-f have provided valuable data on generic relationships, and this will be combined with information from morphology and anatomy to analyze the family phylogeny. DNA sequences have shown conclusively that several African genera of the tribe Homeriinae are nested in the larger genus Moraea and accordingly have been sunk in that genus, leaving Moraea with nearly 200 species.
Goldblatt and Manning have also published local wildflower guides for local regions in South Africa, and have a wildflower guide, Fairest Cape Wildflowers, in press, that covers a large portion of the floristically rich Cape flora region. This work will be published in South Africa and will be distributed by Timber Press in Europe and North America. Goldblatt & Manning contribute regularly to popular journals that deal with African flora and natural history and have articles published in Africa and Veld and Flora. A manual of the extraordinarily rich bulbous flora of the Cape region was completed this year by Goldblatt, Manning and D. Snijman (National Botanic Institute, Kirstenbosch). The extensively illustrated work, dealing with over 1100 species of several monocot families including the Amaryllidaceae, Colchicaceae, Iridaceae, Hyacinthaceae, and some smaller families will be published by Timber Press in 2001.