La torsion de contrainte et le modèle phyllotaxique de Jean

Abstract

The phyllotactic model of Jean is used to analyse the phenomena of biastrepsis in Dipsacus silvestris. The interpretation deduced from Jean's model is compared with those of De Vries and of Plantefol. From the mean values of the divergence angle of seedling rosettes (75.4°) and twisted stems (151.3°), we can determine the phyllotactic series of the system. These results show that the phyllotaxy of Dipsacus silvestris is controlled by the series J(2,5,7,12,19,… ), with J = 1 orJ = 2. By comparing our results with those of De Vries, we can also deduce that in other cases the phyllotaxy of twisted stems is controlled by the series (1,2,3,5,8,… ). This interpretation agrees with other observations and allows us to analyse known facts in a more coherent framework than other studies.