Biohistory Jyournal, Spring, 2004
Research: Index > The vague form created by the environment: Podostemaceae
Research
The time of environment
The vague form created by the environment:
Podostemaceae
Masahiro Kato,
Department of Biological Sciences, Graduate School of Science, The University of Tokyo
    Growing on rocks in rivers, the podostemaceae (left photo) are aquatic plants during the rainy season, and live as terrestrial plants during the dry season. Do you know which of the following three plants are the most closely related?

Liverwort
Hypericum erectum
Rose

    The podostemaceae inhabit a harsh environment, and as their Japanese name suggests, they resemble moss. They come in a variety of forms, including filate, cingulate, and foliate. In fact the forms of this family are rather diverse, and they are the asterales group in true dicotyledons. Recent analysis of their molecular phylogenetics shows they are closely related to the Hypericum family. In short, after branching off from the ancestor they share with the Hypericum, which has a general dicotyledon shape, the podostemaceae rapidly evolved into a form enabling it to cope with their environment.
    Living creatures respond to different environments by evolving. The key to understanding their true form is to start investigating from those that have changed.
The podostemaceae are quite different from the other dicotlyedons
    Podostemaceae have responded to an environment in which they adhere to hard rock to withstand the fast river current. As a result, they have created a form completely different from that of the usual dicotyledon. They have lost the characteristics of the dicotyledon, including a meristem on the shoot apex and radicules, resulting in vague, irregular forms. What genetic changes occurred behind these transformations? It is understood that in this system, evolution can be carefully sought in a unique natural environment, so we would like to use this as our point of entry for plant evolution.

Masahiro Kato
    Received a Ph.D. from the Graduate School of Science at Kyoto University. After serving as an assistant in that university's Faculty of Science, and as an instructor and then an assistant professor at the Faculty of Science at the University of Tokyo, he is currently a professor in the Graduate School of Science at that university.
Primitive life forms and the form of the earth
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