Discussion

Distinction between currants, which mostly lack nodal spines and internodal prickles and have a joint in each pedicel, and gooseberries, which have nodal spines, internodal prickles, and unjointed pedicels, has been made at least since the time of Theophrastus (Q. P. Sinnott 1985), and has been supported by molecular data (A. E. Senters and D. E. Soltis 2003; L. M. Schultheis and M. J. Donoghue 2004). Subgenus Grossularia (Miller) Persoon appears to be monophyletic; disposition of the remaining taxa into subgenera or sections is still in question. M. E. Janczewski (1907) wrote the only worldwide monograph and recognized six subgenera, a view supported by M. Weigend et al. (2002). F. V. Coville and N. L. Britton (1908) provided the most comprehensive treatment of the group for North America and recognized Ribes and Grossularia at generic rank. Some North American floristic treatments have used species circumscriptions of A. Berger (1924). Section Grossularia is the only one in North America that has been comprehensively monographed (Sinnott). No subgeneric classification is presented here. Species are ordered following the phylogenies presented in A. E. Senters and D. E. Soltis (2003) and L. M. Schultheis and M. J. Donoghue (2004), which agree, in general, with the arrangement in F. V. Coville and N. L. Britton (1908), which was repeated, in general, in subsequent floristic accounts. Taxa not treated in the molecular studies have been placed based on morphological similarities. Estimates of numbers of species in Ribes range from 150 to 200. The plants are found primarily in the Northern Hemisphere; it is likely that the diversity within Central America and South America, where rapid speciation has probably occurred, has been greatly underestimated according to M. Weigend and M. Binder (2001) and A. Freire-Fierro (2002). All of the species in subg. (or sect.) Parilla are dioecious and South American, with the northernmost limit of the group being in southern Central America. The other dioecious group, sect. Berisia, is primarily Eurasian. The remaining groups all have some members native in the flora area. Species of Ribes are erect or spreading shrubs, and some form thickets by rooting at the tips of branches. Some have distinctive odors and bear clear, colorless or colored sessile glands that may or may not have a waxy or resinous exudate and/or stalked glands that are clear, and colorless or colored. These stipitate glands may retain their color and shape on herbarium specimens, and in living material may give the flowers or berries a bejeweled appearance. The bark on older stems often shreds or splits to reveal different-colored underlayers. Leaves and inflorescences mostly arise from short shoots. The plants are deciduous in almost all species but in mild climates may be leafless for only a short while. The leaves range from roundish to reniform or are palmately lobed and pentangular, with margins cut to various degrees and mostly toothed or cut again. Degree of lobing in the species descriptions is given as depth of the two most distal sinuses. The inflorescences range from one- to four- to 40+-flowered. The hypanthium ranges from shallow and saucer-shaped to relatively long and narrowly tubular. It is likely that most species produce nectar; the nectary disc is conspicuous only in taxa with saucer-shaped or shallow hypanthia. Long- and short-tongued bees and hummingbirds are the main pollinators, and flowers of some species are visited by butterflies (Q. P. Sinnott 1985). Hybrids between species of Ribes have been achieved experimentally (E. Keep 1962); they are rarely reported from natural populations. W. Messinger et al. (1999) suggested that hybridization may have produced R. lacustre and the xeric, high-elevation R. montigenum of western North America. M. R. Mesler et al. (1991) documented natural hybrids between R. lobbii and R. roezlii var. cruentum, R. binominatum and R. marshallii, and R. binominatum and R. lobbii. They concluded that hybridization between these species is infrequent and localized. The cultivated gooseberries are derived from the European Ribes uva-crispa and the American R. hirtellum; currants are derived from European and Asian species (R. petraeum Wulf, R. rubrum, R. spicatum E. Robson). Currants and gooseberries have been grown for food in North America since the mid 1600s and were commercially grown by the mid 1800s. Some native Ribes have been used for food raw, cooked, or dried. In the descriptions here, palatability or lack thereof is based on information in floras, on herbarium labels, or in reports cited in the Plants for a Future database (www.ibiblio.org/pfaf), not on personal experience of the author. In the early 1900s, some species of Ribes were discovered to be hosts for the telial stage of the white pine blister rust, caused by the fungus Cronartium ribicola Fischer. Other rusts, species of Puccinia Persoon, Melampsora Castagne, and Coleosporium Léveillé, and other species of Cronartium Fries, also infect some Ribes; white pine blister rust has had the greatest economic impact (E. P. Van Arsdel and B. W. Geils 2004). In 1912, United States federal and state regulations were enacted restricting the import and cultivation of Ribes species, and a program to eradicate all Ribes in some areas was implemented. The federal law was rescinded in 1966; some states still ban cultivation of the black currant, R. nigrum. Since 1994, commercial importation of all Ribes material (including fruit-producing and ornamental varieties) from off-continent has been prohibited by Canadian federal law except by special permit. These restrictions have severely impacted commercial production of currants and gooseberries in the United States. Ribes aureum, R. sanguineum, and R. speciosum are native species available in the horticultural trade. Ribes alpinum Linnaeus, native in Eurasia and Africa and used extensively in the horticultural trade in the Canadian prairie provinces, may occasionally persist after cultivation.