POLYPLOIDY, ECOLOGY AND THE BRITISH FLORA.

The article presents a study which examines theoretically the properties of polyploidy in relation to the ecological distribution and behaviour of the whole flora in Great Britain. Polyploidy in the study was estimated as the coefficient of polyploid types (CPT) among types in the subdivision of the flora. The result indicates that polyploidy increases with latitude. It was observed that higher polyploidy of monocots favours the hypothesis that they returned to dry land following aquatic existence which promoted polyploidy. It was also found that both monocot and dicot perennial species have higher CPT's than annuals, and that polyploidy may change diploid annuals to perennials.