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DEVELOPMENT OF TRISTYLY IN PONTEDERIA CORDATA (PONTEDERIACEAE). I. MATURE FLORAL STRUCTURE AND PATTERNS OF RELATIVE GROWTH OF REPRODUCTIVE ORGANS
Author(s) -
Richards Jennifer H.,
Barrett Spencer C. H.
Publication year - 1987
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.1537-2197.1987.tb08785.x
Subject(s) - biology , stamen , ovary , tepal , primordium , botany , ovule , flor , gynoecium , pollen tube , pollination , pollen , biochemistry , gene , endocrinology
Pontederia cordata is a tristylous, self‐incompatible emergent aquatic. Measurements of reproductive organs in mature flowers and developing buds and analysis of relative growth rates of the styles, filaments, and floral tube were used to analyze the developmental processes that result in reciprocal positioning of reproductive parts among the style morphs. Flowers are trimerous with two series of three tepals, two series of three stamens, and a tricarpellate ovary with a single ovule. Each flower has stamens of two lengths, but the two lengths correspond to upper vs. lower position in the zygomorphic flowers, not to the two series initiated in the primordium. Morph‐dependent variation in stigma height depends on differences in style length, not ovary length. Differences among morphs in anther height result from differences in the position of filament insertion on the floral tube and differences in filament length. Styles of the three morphs develop to different lengths as a result of two distinct processes. Styles of L and M morphs develop at different rates with the L style growing more rapidly than the M style, whereas styles of the S morph have a brief period of rapid growth followed by early inhibition. Stamen growth in the S morph also differs qualitatively from that in the L and M morphs, which are distinguished from each other by quantitative differences in growth rates. Results indicate that the developmental processes that result in the complementary arrangements of organs in different morphs are morph‐specific. An attempt is made to integrate the findings of this study with the model for genetic control of tristyly.