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THE HETEROCHRONIC ORIGIN OF THE CLEISTOGAMOUS FLOWER IN ASTRAGALUS CYMBICARPOS (FABACEAE)
Author(s) -
Gallardo Rafael,
Dominguez Eugenio,
Muñoz Jesus M.
Publication year - 1993
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1993.tb15297.x
Subject(s) - heterochrony , biology , gynoecium , neoteny , stamen , allometry , botany , pollen , ontogeny , zoology , paleontology , genetics
Members of the species Astragalus cymbicarpos form chasmogamous and cleistogamous flowers, as well as a large variety of intermediate floral types. Bivariate allometry and Gould's clock models were used to investigate the possible heterochronic evolution of the cleistogamous flower from the chasmogamous flower. In three of the whorls analyzed (pistil, stamens, and corolla) comparison of chasmogamous, pseudocleistogamous, and cleistogamous flowers revealed a progressive “juvenilization” of the adult form. This paedomorphic morphology proved to be partly the result of a process of progenesis, also evident in acceleration of sexual maturity. The retardation of shape with respect to size in these three whorls suggests, however, the existence of a heterochronic process other than progenesis.