Éléments pour une approche morphométrique de la croissance végétale et de la floraison : le cas d'espèces tropicales du modèle de Leeuwenberg

Abstract

A quantitative description of primary growth from the apical meristem activity is proposed for four tropical plants: Alstonia vieillardii var. vieillardii (Apocynaceae), Miconia ciliata (Melastomaceae), Ricinus communis (Euphorbiaceae), and Solanum rugosum (Solanaceae). The development of these four plants corresponds to Leeuwenberg's model. Three parameters were measured at different stages of plant growth: leaf surface, length of the underlying internode, and the surface of the internode section. Two other parameters were derived from these three: parameter T, which summarizes the first three parameters and corresponds to the overall dimension of the leaf–internode system, and parameter D, showing the differential evolution of the leaf surface and the corresponding axial volume. The higher the D value, the higher the predominance shown by the twig over the leaf component. This phenomenon is named axialization. The reciprocal situation is called foliarization. For parameter T, the observed variations are present in all four species and showed an increase followed by a decrease in dimensions during the growth process. From the evolution of parameter D, two processses can be recognized. In A. vieillardii var. vieillardii and Solanum rugosum, the amplitude of variation is wide and can be compared with that of parameter T. In M. ciliata and R. communis, the amplitude of variation is significantly reduced. A link can be established between this morphometric evolution and flowering. The results obtained for these four species are compared with those obtained by other researchers and bring new elements to the study of the relationship between the vegetative evolution of the plant and its flowering. Key words: architecture, morphometry, Leeuwenberg's model, ontogeny. [Journal translation]