Phytogeographic Chronicle

This article is a review on the treatise of P. LEGRIS on "The Vegetation of INDIA, Ecology and Flora". In the first part on habitat factors, the bioclimate of the sub-continent is analysed and an original formula is proposed on hydric balance expressed as P - xDs wherein P=annual precipitation, x=xerothermic index and Ds=mean eficit of saturation during the dry season. The vegetation of the entire country is treated on the basis of dynamism and ecological conditions. A number of "series" are recognised within the four main formations: wet, dry, thorny and Himalayan, according to the principles of GAUSSEN. The analysis of the floral elements of the various forest types and the past history of the vegetation are amongst the many interesting phytogeographic aspects treated in this monumental work.