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A revision of Rhododendron section Pentanthera

Published online by Cambridge University Press:  26 April 2010

K. A. Kron
K. A. Kron
Affiliation:
Department of Botany, University of Florida, Gainesville, FL 32611, USA.
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Abstract

Rhododendron sect. Pentanthera G. Don (Ericaceae) comprises a group of closely related, highly ornamental plants which are commonly called ‘azaleas'. Thirteen of the fifteen species recognized in this section are indigenous to North America. One species (R. molle) is native to Japan and China, and one species (R. luteum) is indigenous to the Caucasus region. Phylogenetic analysis of the species within the section indicates that R. molle is the sister to the rest of the section. It is the sole member of R. subsect. Sinensia. The remaining species form a monophyletic group recognized as R. subsect. Pentanthera. Within this subsection the presence of a blotch on the upper corolla lobe defines two primarily orange to red-flowered groups. The first group has a Tertiary Period disjunct distribution and comprises R. luteum, R. austrinum and R. occidentale. The second group is indigenous to eastern North America and comprises R. calendulaceum, R. cumberlandense, R. flammeum, R. prunifolium and R. alabamense. In both groups the cladistically basal species has white flowers with a yellow blotch on the upper corolla lobe (R. occidentale, R. alabamense, respectively). The pink to white early flowering species R. canescens, R. periclymenoides and R. prinophyllum do not form a monophyletic group.

Phenetic analyses indicate that the eastern Asian taxon, R. molle, is best recognized as one species with two geographical subspecies; Rhododendron prinophyllum is quite distinct from R. canescens and R. periclymenoides. The latter two species are very similar morphologically, but their similarities are due to the retention of primitive characters and they should be recognized as distinct species. Rhododendron calendulaceum can be distinguished from R. cumberlandense using a combination of morphological and phenological characters. The various taxa previously segregated out of R. viscosum are merely extreme forms of a widespread and variable species and are not given any formal rank. No subspecific taxa are recognized for R. occidentale. Distribution maps, keys to the species, species descriptions and specimen citations are included.

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Edinburgh Journal of Botany , Volume 50 , Issue 3 , November 1993 , pp. 249 - 364
Copyright
Copyright © Trustees of the Royal Botanic Garden Edinburgh 1993

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References

REFERENCES

Alexander, E. G. (1935). Azalea arborescens. Addisonia 19: 17–18, pl. 617.Google Scholar
André, E. F. (1871). Azalea mollis Blume. Mini Hort. 18: 132 t. 68.Google Scholar
Ashe, W. W. (1921). Notes on Rhododendron. Rhodora 23: 177–179.Google Scholar
Barnhart, J. H. (1895). Proceedings of the Torrey Botanical Club, Wed. evening. Bull. Torrey Bot. Club 22: 282.Google Scholar
Bartram, W. (1791). Travels in North and South Carolina, Georgia and East Florida. Ed. 1. James and Johnson, Philadelphia.Google Scholar
Blanchard, W. H. (1902). Some Vermont and New Hampshire plants in the Middle Connecticut Valley. I. Rhodora 4: 129–133.Google Scholar
Bowers, C. G. (1927). Rhododendrons and azaleas for breeding purposes in America. J. New York Bot. Gard. 28: 81–86.Google Scholar
Bowers, C. G. (1936). Rhododendrons and azaleas. Their origins, cultivation and development. Macmillan, New York.Google Scholar
Bowers, C. G. (1954). Winter hardy azaleas and rhododendrons. The Massachusetts Hort. Soc., Boston.Google Scholar
Braun, E. L. (1941). The red azaleas of the Cumberlands. Rhodora 43: 31–35.Google Scholar
Clausen, R. T. (1941). On the uses of the terms “subspecies” and “variety”. Rhodora 43: 157–167.Google Scholar
Coker, J. L. (1920). Azalea atlantica Ashe and its variety luteo-alba n. var. J. Elisha Mitchell Sci. Soc. 36: 97–99.Google Scholar
Cowan, J. M. (1950). The rhododendron leaf: a study of epidermal appendages. Oliver & Boyd, Edinburgh.Google Scholar
Creech, J. L. (1962). A distribution note on Rhododendron japonicum. Amer. Hort. Mag. 41: 174–177.Google Scholar
Cullen, J. (1980). Rhododendron taxonomy and nomenclature. In: Luteyn, J. ' Brien, M. (eds) Contributions toward a classification of Rhododendron. Proc. Int. Rhododendron Conf, pp. 27–38. NY Bot. Garden, Bronx, NY.Google Scholar
Day, M. A. (1899). Plants from the eastern slope of Mt. Equinox. Rhodora 1: 220–222.Google Scholar
Dequeiroz, K. & Donoghue, M. J. (1988). Phylogenetic systematics and the species problem. Cladistics 4: 77–81.Google Scholar
Dequeiroz, K. & Donoghue, M. J. (1990). Phylogenetic systematics and species revisited. Cladistics 6: 83–90.Google Scholar
Donoghue, M. J. (1985). A critique of the biological species concept and recommendations for a phylogenetic alternative. Bryologist 88: 172–181.CrossRefGoogle Scholar
Donoghue, M. J. & Cantino, P. D. (1984). The logic and limitations of the outgroup substitution approach to cladistic analysis. Syst. Bot. 9: 192–202.Google Scholar
Drude, O. (1889). Ericaceae. In: Engler, A. & Prantl, K. (eds) Die natürlichen Pflanzenfamilien, Vol. 4, Part 1, pp. 15–65. Hans Melchior and Erich Weidermann, Leipzig.Google Scholar
Duhamel, Du Monceau H. L. (1812). Traite des arbres et arbuste que Von cultivi en France en pleine terre. Vol. 5: 221–227.Google Scholar
Evans, D., Kane, K. H., Knights, B. A. & Math, V. B. (1980). Chemical taxonomy of the genus Rhododendron. In: Luteyn, J. & O'Brien, M. (eds) Contributions toward a classification of Rhododendron. Proc. Int. Rhododendron Conf., pp. 187–245. NY Bot. Garden, Bronx, NY.Google Scholar
Federal Register. (1980). Endangered and threatened wildlife and plants: Review of plant taxafor listing as endangered or threatened species. Federal Register Vol. 45, No. 242, part iv, lc. 82480–82569. US Department of the Interior, Washington, DC.Google Scholar
Fernald, M. L. (1940). Some spermatophytes of eastern North America. Rhodora 42: 239–246.Google Scholar
Fernald, M. L. (1941). Another century of additions to the flora of Virginia. Rhodora 43: 485–553.Google Scholar
Fernald, M. L. (1942). Misinterpretation of Atlantic Coastal Plain species. Rhodora 44: 238–246.Google Scholar
Galle, F. (1968). Native and some introduced azaleas for southern gardens. Booklet #2. Callaway Gardens, Pine Mt. Georgia.Google Scholar
Galle, F. (1985). Azaleas. Timber Press, Portland, Oregon.Google Scholar
Godfrey, R. K. & Wooten, J. W. (1981). Aquatic and wetland plants of southeastern U.S.: dicotyledons. University of Georgia Press, Athens.Google Scholar
Goldy, R. G. & Lyrene, P. M. (1984). Pentaploid blueberries from 6x x 2x crosses. J. Amer. Soc. Hort. Sci. 109: 218–221.Google Scholar
Haberer, J. V. (1905). Plants of Oneida Co., New York and vicinity. I. Rhodora 7: 106–110.Google Scholar
Hallé, F., Oldeman, R. A. A. & Tomlinson, P. B. (1978). Tropical trees and forests: an architectural analysis. Springer-Verlag, Berlin.CrossRefGoogle Scholar
Harborne, J. B. (1980). Flavonoid pigments as both taxonomic and phyletic markers in the genus Rhododendron. In: Luteyn, J. & O'Brien, M. (eds) Contributions toward a classification of Rhododendron. Proc. Int. Rhododendron Conf, pp. 145–161. NY Bot. Garden, Bronx, NY.Google Scholar
Harborne, J. B. & Williams, C. A. (1971). Leaf survey of flavonoids and simple phenols in the genus Rhododendron. Phytochemistry 10: 2727–2744.CrossRefGoogle Scholar
Harkness, B. (1932). Rhododendron atlanticum Rehder. Nat. Hort. Mag. 11: 55.Google Scholar
Hayes, S. F., Keenan, J. & Cowan, J. M. (1951). A survey of the anatomy of the Rhododendron leaf in relation to the taxonomy of the genus. Notes Roy. Bot. Gard. Edinburgh 21: 1–34.Google Scholar
Hedegaard, J. (1980). Morphological studies in the genus Rhododendron dealing with seeds, fruits and seedlings and their associated hairs. In: Luteyn, J. & O'Brien, M. (eds) Contributions toward a classification of Rhododendron. Proc. Int. Rhododendron Conf., pp. 117–144. NY Bot. Garden, Bronx, NY.Google Scholar
Heiser, C. B., Jr (1973). Introgression re-examined. Bot. Rev. 39: 347–366.CrossRefGoogle Scholar
Hendy, M. D. & Penny, D. (1982). Branch and bound algorithms to determine minimal evolutionary trees. Math. Biosci. 59: 277–290.CrossRefGoogle Scholar
Hennig, W. (1966). Phylogenetic systematics. University of Illinois Press, Urbana.Google Scholar
Holmgren, P. K., Keuken, W. & Schofield, E. K. (eds) (1981). Index Herbariorum. Part I: The herbaria of the world.Ed.7. Dr W. Junk, B.V. Publ., Boston.Google Scholar
Hsü, J. (1983). Late Cretaceous and Cenozoic vegetation in China, emphasizing their connections with North America. Ann. Missouri Bot. Gard. 70: 490–508.CrossRefGoogle Scholar
International Code Of Botanical Nomenclature. (1981). E. G. Voss (Chairman). Utrecht, The Netherlands.Google Scholar
Janaki-Ammal, E. K., Enoch, I. C. & Bridgwater, M. (1950). Chromosome numbers in species of Rhododendron. The Rhododendron Yearbook 5: 78–91. Royal Horticultural Society.Google Scholar
Jepson, W. L. (1939). A Flora of California 3: 17–128.Google Scholar
Judd, W. S. (1981). A monograph of Lyonia (Ericaceae). J. Arnold Arb. 62: 63–209, 315–436.CrossRefGoogle Scholar
Kellner, C. V. (1978). Are pollinators exerting selection pressure on the azalea hybrids on Gregory Bald? MS thesis. University of Tennessee, Knoxville.Google Scholar
King, B. L. (1977a). The flavonoids of the deciduous Rhododendron of North America. Amer. J. Bot. 64: 350–360.CrossRefGoogle Scholar
King, B. L. (1977b). Flavonoid analysis of hybridization in Rhododendron section Pentanthera (Ericaceae). Syst. Bot. 2: 14–27.CrossRefGoogle Scholar
King, B. L. (1980). The systematic implications of flavonoids in Rhododendron subgenus Pentanthera. In: Luteyn, J. & O'Brien, M. (eds) Contributions toward a classification of Rhododendron. Proc. Int. Rhododendron Conf, pp. 163–186. NY Bot. Garden, Bronx, NY.Google Scholar
Kingdon-Ward, F. (1935). Rhododendron seeds, with special reference to their classification. J. Bot. 73: 241–247.Google Scholar
Knowlton, C. H. (1919). An excursion to Mt. Washington, Mass, and Bash-Bish Falls. Rhodora 21: 198–202.Google Scholar
Knowlton, C. H. & Deane, W. (1922). Reports on the flora of the Boston district. XXXVI. Rhodora 24: 152–156.Google Scholar
Kron, K. A. (1989). Azalea rosea is a superfluous name. Sida 13: 331–333.Google Scholar
Kron, K. A., Gawen, L. M. & Chase, M. W. (1993). Evidence for introgression in azaleas (Rhododendron, Ericaceae): chloroplast DNA and morphological variation in a hybrid swarm on Stone Mountain, Georgia. Amer. J. Bot. 80: 1095–1099.CrossRefGoogle Scholar
Lawrence, G. H. M. (1954). The status of Rhododendron nudiflorum and R. roseum. Baileya 2: 1–3.Google Scholar
Lemmon, W. P. (1938). Notes on a study of the southeastern azaleas with descriptions of two new species. Bartonia 19: 14–17.Google Scholar
Li, H. L. (1952). Floristic relationships between eastern Asia and eastern North America. Trans. Amer. Philos. Soc. 42: 371–29.Google Scholar
Li, H. L. (1957). Chromosome studies in the azaleas of eastern North America. Amer. J. Bot. 44: 8–14.CrossRefGoogle Scholar
Linnaeus, C. (1753). Species Plantarum. 2nd facsimile ed. Ray Society, London.Google Scholar
Little, E. L. (1970). Endemic, disjunct and northern trees in the southern Appalachians. In: Holt, P. C. (ed.) The distributional history of the biota of the southern Appalachians. Part II: Flora. Research Division Monograph 2, Virginia Polytechnic Institute and State University, Blacksburg, Virginia.Google Scholar
Luteyn, J. L. (1983). Ericaceae—Part 1. Cavendishia. Fl. Neotrop. Monogr. 35.Google Scholar
Maddison, W. P., Donoghue, M. J. & Maddison, D. R. (1984). Outgroup analysis and parsimony. Syst. Zool. 33: 83–103.Google Scholar
Makino, T. (1956). An illustrated flora of Japan. Hokuryukan, Tokyo.Google Scholar
Mayr, E. (1969). Principles of systematic zoology. McGraw-Hill, New York.Google Scholar
McCullough, M. A. (1985). Exploring for the western azalea in southern California. J. Amer. Rhododendron Society 39: 70–74.Google Scholar
Mlchaux, A. (1803). Flora boreali-americana. Vol. 1. Facsimile, ed. Hafner Press, New York.Google Scholar
Millais, J. G. (1917). Rhododendrons and the various hybrids. Vol. 1. Longmans Green, London.Google Scholar
Mishler, B. D. (1985). The morphological, developmental, and phylogenetic basis of species concepts in bryophytes. Bryologist 88: 207–214.Google Scholar
Mishler, B. D. & Donoghue, M. J. (1982). Species concepts: A case for pluralism. Syst. Zool. 31: 491–503.CrossRefGoogle Scholar
Mossman, F. D. (1977). The western azalea on Stagecoach Hill. Pacific Hort. 38: 28–33.Google Scholar
Nakai, T. (1922). Trees and shrubs indigenous to Japan proper. Vol. 1. Seibido Shoten, Nihombashi. Tokyo.Google Scholar
Nakamura, M. (1931). Caryological studies on the genus Rhododendron. J. Soc. Trop. Agric, Tohuku Imperial Univ. 3: 103–109.Google Scholar
Philipson, M. N. (1980). Cotyledons and Rhododendron classification. In: Luteyn, J. & O'Brien, M. (eds) Contributions toward a classification of Rhododendron. Proc. Int. Rhododendron Conf., pp. 75–88. NY Bot. Garden, Bronx, NY.Google Scholar
Philipson, W. R. & Philipson, M. N. (1968). Diverse nodal types in Rhododendron. J. Arnold Arbor. 49: 193–224.CrossRefGoogle Scholar
Porter, T. C. (1889a). Notes on two Rhododendrons. Bull. Torrey Bot. Club 16: 220–221.CrossRefGoogle Scholar
Porter, T. C. (1889b). Flora of the Pocono Plateau. Rhodora 1: 182–185.Google Scholar
Prince, M. (1978). Our wild eastern treasures: native azaleas. Amer. Hort. Mag. 57: 13–17.Google Scholar
Radford, R. E., Ahles, H. E. & Bell, C. R. (1968). Manual of the vascular flora of the Carolinas. University of North Carolina Press, Chapel Hill.Google Scholar
Raven, P. H. (1975). The bases of angiosperm phylogeny: cytology. Ann. Missouri Bot. Gard. 62: 724–764.Google Scholar
Rehder, A. (1921). A monograph of the azaleas of North America. In: Wilson, E. H. & Rehder, A.A monograph of azaleas. Publication of the Arnold Arboretum No. 9. Harvard University, Cambridge, Mass.Google Scholar
Rehder, A. (1947). Two new forms of Rhododendron roseum. Contr. Gray Herb. 165: 9–11.Google Scholar
Sargent, C. S. (1917). American azaleas and their hybrids. Rhododendron Soc. Notes 1: 119–121.Google Scholar
Sax, K. (1930). Chromosome stability in the genus Rhododendron. Amer. J. Bot. 17: 247–251.Google Scholar
Schneider, E. (1969). Azalea viscosa hybriden. Dendroflora 6: 50–52.Google Scholar
Shinners, L. H. (1961). Rhododendron coryi, a new repent species from southeastern Texas. Castanea 26: 156–157.Google Scholar
Shinners, L. H. (1962).Rhododendron nudiflorum and R. roseum (Ericaceae)—Illegitimate names. Castanea 27: 94–95.Google Scholar
Seithe-Von Hoff, A. (1960). Die Haarformen der Gattung Rhododendron L. und die Möglichkeit ihrer taxonomischen Verwertung. Bot. Jahr. Syst. 79: 297–393.Google Scholar
Seithe-Von Hoff, A. (1980). Rhododendron hairs and taxonomy. In: Luteyn, J. & O'Brien, M. (eds) Contributions toward a classification of Rhododendron. Proc. Int. Rhododendron Conf., pp. 89–116. NY Bot. Garden, Bronx, NY.Google Scholar
Sims, J. (1815). Rhododendron calendulaceum var. crocea. Bot. Mag. 41: pi. 1721.Google Scholar
Skinner, H. T. (1952). Character patterns in the flowering azaleas of the southern U.S. Yearb. Amer. Philos. Soc. (1952): 177–179.Google Scholar
Skinner, H. T. (1955). In search of native azaleas. Morris Arbor. Bull. 6: 1–10, 15–22.Google Scholar
Skinner, H. T. (1959). An evaluation of our eastern wild azaleas. Arbor. Bull. 22: 80–81,106.Google Scholar
Skinner, H. T. (1961). Classification of the native American azaleas. Proc. Int. Rhododendron Conf., pp. 81–86. [American Rhododendron Society, Portland, Oregon, May 11–14.]Google Scholar
Skinner, H. T. (1965). Chapter 21. Deciduous Species and Named Varieties. In: Lee, F. P.The azalea book, pp. 191–228. Ed. 2. D. Van Nostrand, Princeton, New Jersey.Google Scholar
Skinner, H. T. (1971). America's native azaleas. Pl. & Gard. 27: 30–35.Google Scholar
Sleumer, H. (1966). An account of Rhododendron in Malesia. Fl. Males, ser. 1,6: 473–674.Google Scholar
Sleumer, H. (1980). Past and present taxonomic systems of Rhododendron based on macromorphological characters. In: Luteyn, J. & O'Brien, M. (eds) Contributions toward a classification of Rhododendron. Proc. Int. Rhododendron Conf., pp. 19–26. NY Bot. Garden, Bronx, NY.Google Scholar
Small, J. K. (1903). Flora of the southeastern U.S. New York.Google Scholar
Sneath, P. H. A. & Sokal, R. R. (1973). Numerical taxonomy—the principles and practice of numerical classification. W. H. Freeman, San Francisco.Google Scholar
Solymosy, S. L. (1974). Notes on Rhododendron coryi Shinners. Bull. Amer. Rhododendron Soc. 28: 188–189.Google Scholar
Solymosy, S. L. (1976). A treatise on azaleas. Louisiana Society for Horticultural Research, Vol. 4.Google Scholar
Spethmann, W. (1980). Flavonoids and carotenoids of Rhododendron flowers and their significance for the classification of the genus Rhododendron. In: Luteyn, J. & O'Brien, M. (eds) Contributions toward a classification of Rhododendron. Proc. Int. Rhododendron Conf., pp. 247–275. NY Bot. Garden, Bronx, NY.Google Scholar
Stevens, P. F. (1970). A classification of the Ericaceae: subfamilies and tribes. J. Linn. Soc, Bot. 64: 1–53.Google Scholar
Stevens, P. F. (1980a). Evolutionary polarity of character states. Annual Rev. Ecol. Syst. 11: 333–358.Google Scholar
Stevens, P. F. (1980b). A revision of the Old World species of Calophyllum (Guttiferae). J. Arnold Arbor. 61: 117–690.Google Scholar
Steward, A. N. (1958). Manual of vascular plants of the lower Yangtze Valley, China. Oregon State College, Corvallis, OR.CrossRefGoogle Scholar
Swofford, D. (1993). PAUP: Phylogenetic analysis using parsimony, version 3.1.1. Computer program distributed by the Illinois Natural History Survey, Champaign, Illinois.Google Scholar
Szafer, W. (1975). General plant geography. Naukowe, Warsaw. (Translated from Polish by Massey, Helen M. for the Smithsonian Institution.)Google Scholar
Valckenier-Suringar, J. (1904). Azalea mollis und Azalea sinensis. Mitt. Deutsch. Dendrol. Ges. 13: 53–54.Google Scholar
Valckenier-Suringar, J. (1908). Azalea mollis und Azalea sinensis. Gartenflora 57: 505–517, pls 1575–1576.Google Scholar
Watrous, L. E. & Wheeler, Q. D. (1981). The out-group comparison method of character analysis. Syst. Zool. 30: 1–11.CrossRefGoogle Scholar
Watson, L. (1964). The taxonomic significance of certain anatomical observations on Ericaceae, the Ericoideae, Calluna and Cassiope. New Phytol. 63: 274–280.Google Scholar
Watson, L. (1965). The taxonomic significance of certain anatomical variations among Ericaceae. J. Linn. Soc. Bot. 59: 111–121.CrossRefGoogle Scholar
Weatherby, C. A. & Griscom, L. (1934). Notes on the spring flora of the coastal plain of South Carolina north of Georgetown. Rhodora 36: 28–54.Google Scholar
Weigand, K. M. (1924). Some changes in nomenclature. Rhodora 26: 1–5.Google Scholar
Wldrlechner, M. P., Pellett, H. M. & Ascher, P. D. (1984). Observations on phylogenetic relationships between Rhododendron calendulaceum and R. bakeri. J. Rhododendron Species Found. 1:49–63.Google Scholar
Wilbur, R. L. (1976). Illegitimate names Rhododendron nudiflorum (L.) Torr. and R. roseum (Loisel.) Rehder. Taxon 25: 178–179.CrossRefGoogle Scholar
Wiley, E. O. (1981). Phylogenetics: the theory and practice of phylogenetic systematics. Wiley, New York.Google Scholar
Willdenow, C. L. (1811). Berlinische Baumzucht oder Beschreibung der in Königlichen botanischen Garten bei Berlin im Freien ausdauernden. G. C. Nauck, Berlin.Google Scholar
Willingham, F. F., Jr (1973). A biosystematic study of bloom forms of Rhododendron calendulaceum. PhD Dissertation. Wake Forest University.Google Scholar
Willingham, F. F., Jr (1974). Variation in Rhododendron calendulaceum (Michx.) Torr. (Ericaceae) of the Nantahala Mountains, North Carolina. ASB Bull. 21: 90–91.Google Scholar
Willingham, F. F., Jr (1975). Taxonomy of the flowering forms of Rhododendron calendulaceum. Bull. Amer. Rhododendron Soc. 29: 183–186.Google Scholar
Willingham, F. F., Jr (1976). Variation and phenological forms in Rhododendron calendulaceutn. Castanea 41: 215–223.Google Scholar
Wilson, E. H. (1921). A monograph of azaleas of the Old World. In: Wilson, E. H. & Rehder, A.A monograph of azaleas, pp. 1–106. Publication of the Arnold Arboretum No. 9. Harvard University, Cambridge, Mass.Google Scholar
Wilson, E. H. & Rehder, A. (1921). A monograph of azaleas. Publication of the Arnold Arboretum No. 9. Harvard University, Cambridge, Mass.Google Scholar
Wishart, D. (1975). CLUSTAN Version 2.1. User's manual. University College London.Google Scholar
Wood, C. E. (1961). The genera of Ericaceae in the southeastern United States. J. Arnold Arbor. 42: 10–80.Google Scholar
Wood, C. E. (1970). Some floristic relationships between the southern Appalachians and western North America. In: Holt, P. C. (ed.) The distributional history of the biota of the southern Appalachians. Part II: Flora. Research Division Monograph 2, Virginia Polytechnic Institute and State University, Blacksburg, Virginia.Google Scholar