Abstract
The floral vascular anatomy of 12 species representing each ofAsarum s. str.,Asiasarum, Geotaenium, Heterotropa andHexastylis are compared to clarify intergeneric relationships. The five genera have basically similar structures in floral morphology and vasculature, and consistently have a six-carpelled compound ovary and the associated similar placental vasculature. They show, however, a significant difference in the position and the constituent of the “ventral” carpellary bundles in the placental axis betweenAsiasarum-Heterotropa-Hexastylis andAsarum-Geotaenium. InAsiasarum, Heterotropa andHexastylis the ventral bundles of each carpel are basically free and antilocular as expected in the least specialized compound ovary of angiosperms; in contrast, inAsarum andGeotaenium the ventral carpellary bundles are antiseptal and heterogenous (i.e., formed by the lateral fusion of ventral bundles of adjacent carpels). Shared probable apomorphic floral vasculature, as well as shared single style-column, suggests the closest mutual relationships betweenAsarum andGeotaenium. In terms of floral morphology and anatomy,Asiasarum, Heterotropa andHexastylis retain plesiomorphies. Possible chromosomal evolution in the related genera is also discussed.
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References
Blomquist, H.L. 1957. A revision ofHexastylis of North America. Brittonia8: 255–281.
Cheng, C.Y. andC.S. Yang 1983. A synopsis of the Chinese species ofAsarum (Aristolochiaceae). J. Arnold Arbor.64: 565–597.
Eames, A.J. 1931. The vascular anatomy of the flower with refutation of the theory of carpel polymorphism. Amer. J. Bot.18: 147–188.
— 1961. Morphology of the Angiosperms. McGraw-Hill Book Co., New York.
— andL.H. MacDaniels. 1947. An Introduction to Plant Anatomy, 2 ed. McGraw-Hill Book Co., New York.
Endo, J., T. Nakamura andM. Nagasawa 1976. Geographical variation ofAsarum caulescens Maxim. J. Jap. Bot:51: 209–219 (in Japanese).
Lawrence, G.H.M. 1951. Taxonomy of Vascular Plant. Macmillan & Co., New York.
Maekawa, F. 1953. Geohistorical distribution of East Asiatic Asaraceae. Proc. VII Pacific Sci. Congr. (Wellinton)5: 217–219.
— 1978. Notes onAsarum andHeterotropa from Taiwan. J. Jap. Bot.53: 289–299 (in Japanese).
Nair, N.C. andK.R. Narayanan 1962. Studies on the Aristolochiaceae I. Nordal and floral anatomy. Proc. Nat. Inst. Sci. India28: 211–227.
Puri, V. 1951. The role of floral anatomy in the solution of morphological problems. Bot. Rev.17: 471–553.
Saunders, E.R. 1939. Floral Morphology. A New Outlook, with Special Reference to the Interpretation of the Gynoecium. Cambridge Univ. Press, Cambridge.
Soltis, D.E. 1984. Karyotypes of species ofAsarum andHexastylis (Aristolochiaceae). Syst. Bot.9: 490–493.
Sugawara, T. 1981. Taxonomic studies ofAsarum sensu lato I. Karyotype and C-banding pattern inAsarum s. str.,Asiasarum andHeterotropa. Bot. Mag. Tokyo94: 225–238.
— 1982. Taxonomic studies ofAsarum sensu lato II. Karyotype and C-banding pattern in two species ofHexastylis andAsarum epigynum. Bot. Mag. Tokyo95: 295–302.
— 1985. Further investigations on karyotype and C-banding pattern in seven species ofHeterotropa. J. Jap. Bot.60: 15–23.
— andM. Ogisu. 1986. Karyotype analysis of five species ofAsarum (Aristolochiaceae) in Sichuan, China. J. Jap. Bot.61: 104–111.
Utech, F.H. 1978. Vascular floral anatomy ofHelonias bullata (Liliaceae-Helonieae), with a comparison to the AsianHeloniopsis orientalis. Ann. Carnegie Mus.47: 169–191.
Wyatt, R.L. 1955. An embryological study of four species ofAsarum. J. Elisha Mitchell Sci. Soc.71: 64–82.
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Sugawara, T. Taxonomic studies ofAsarum sensu lato. Bot Mag Tokyo 100, 335–348 (1987). https://doi.org/10.1007/BF02488853
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DOI: https://doi.org/10.1007/BF02488853