You are not currently logged in.
Access JSTOR through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
The Plastochron index in Developmental Studies of Xanthium italicum Moretti
Francis J. Michelini
American Journal of Botany
Vol. 45, No. 7 (Jul., 1958), pp. 525-533
Published by: Botanical Society of America, Inc.
Stable URL: http://www.jstor.org/stable/2439575
Page Count: 9
You can always find the topics here!Topics: Leaves, Plants, Chlorophylls, Oxygen, Morphological indexes, Plant morphology, Leaf development, Subject terms, Plant growth, Morphogenesis
Were these topics helpful?See something inaccurate? Let us know!
Select the topics that are inaccurate.
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
Develepomental studies in higher plants have been seriously hampered by the difficulty of obtaining parallel samples of experimental materials. When chronological age is used as a selecting criterion in such studies, reproducibility is very limited. Recent advances in biochemical and physiological knowledge have brought an increase in the understanding of many of the specific reactions involved in growth and differentiation and makes more important the linking of these processes to development. In this study on Xanthium italicum Moretti an attempt was made to establish a relationship between various morphological stages of the developing plant and certain of its physiological activities. Leaves of Xanthium in various stages of development were collected and analyzed for fresh weight, dry weight, chlorophyll content and oxygen consumption. There was no consistent relationship noted between the developing leaf and these physiological characteristics on the basis of the selecting criteria of chronological age. Utilizing a previously established formula, the plastochron index, for expressing development in terms of leaf morphology it was found that the fresh weight, dry weight, chlorophyll synthesis and oxygen uptake of individually developing leaves followed a straight line relationship to their particular stage of growth. Interpretations of leaf morphogenesis in terms of relative rates of these variables are discussed. It is suggested that the use of the plastochron index or a comparable developmental scale may be a reliable tool in the interpretation of physiological processes and morphological changes during growth and development.
American Journal of Botany © 1958 Botanical Society of America, Inc.