Évolution de paramètres morphologiques au cours du cycle de croissance de Callisia fragrans (Commelinaceae)

Abstract

The growth habits in Callisia fragrans are studied in relation to the variation of simple morphological parameters such as the leaf area and the internode length and diameter. The architecture of this species being simple, as in many Monocotyledons, these parameters are the main morphological indicators for the different phases of the biological cycle. Five phases have been distinguished: the stolon, the establishment of the leafy stem, the indefinite growth of the leafy stem, the transition to flowering, and the final stage of flowering with the production of axillary flowers. The establishment of the leafy stem and the transition to flowering are two evolutionary phases while the others are stabilized. The quantitative study of the parameters shows that the stem diameter is always positively correlated to the leaf area while the internode length is negatively correlated to the leaf area mainly during the evolutionary phases. The internode lengthening coefficient, which expresses the internode shape, is negatively correlated to the leaf area. The correlations in C. fragrans are compared to those observed in previous studies, and some general laws concerning the evolution of the morphological parameters are formulated.