A NUMERICAL TAXONOMIC STUDY OF THE POLYGONUM-AVICULARE COMPLEX (POLYGONACEAE) IN BELGIUM

16 morphological characters were assessed in 300 plants sampled from 27 populations of Polygonum aviculare sensu lato representative of the whole ecological range of the species in Belgium. The three multivariate treatments performed, namely principal component analysis, cluster analysis and discriminant analysis provide evidence that P. aviculare can be divided in 4 units, roughly corresponding to the four taxa recognized by Chrtek. However, the results point out that subsp. monspeliense and subsp. calcatum should be included at the varietal rank within respectively subsp. aviculare (=P. heterophyllum) and subsp. aequale (=P. arenastrum) as defined by Lindman. Fruit dimensions, fruit shape and tepal length are the most discriminant characters for separating the four taxa, while several other characters are discriminant at the population level only. The evolutionary significance of the variation pattern of the whole complex is discussed in terms of life history differentiation and ecological specialization. © 1990 Springer-Verlag.