Abstract Chemotaxonomy of the genus Salicornia in the north-adriatic coasts. — Serological and chemical methods have been applied to investigate the systematics of Salicornia, a genus of halophilous Chenopodiaceae where cleistogamy is frequent. The research, limited to north-adriatic material, involved 13 populations (Tab. 1) belonging to all presently known italian taxa: the tetraploid (2n=36) S. veneta; a newly found triploid form (2n=27); a set of diploid forms (2n=18) which range morphologically from S. europaea-like to S. ramosissima-like populations. The aim of the research is to attempt a systematic ordination of these forms, with special emphasis on the strongly polymorphic diploid complex. From all populations a large number of individuals were sampled randomly and the soluble proteins extracted from the mature seeds. The extracts have been used for electrophoresis and for immunization of rabbits: antisera for five populations have been obtained and tested against all extracts (Figs. 1–5). The possibility of distinguishing at the level of population by means of the analysis of seed proteins has been demonstrated. No specific proteins of any populations could be found, as all populations appear to have the same complex of antigens; however, differences in the quantity of individual proteins (Tab. 2) and in the electrophoretic mobility of immunologically equivalent proteins have been observed in the different populations. The electrophoretic strips (Fig. 6) have been examined with numerical methods (Tab. 3 and 4, Figs. 7 and 8) to try a systematic assessment of the material. It risulted that the electrophoretic characters are distributed without correlations one with another; the same is true for the serological characters; ordering based on serological or electrophoretic characters results in a cline; also, the ordinations based on these chemical characters do not correspond one with the other, nor with ordinations based on morphology, on geographic distribution, on ecology. Because of the particular distribution of the characters a systematic assessment of the group appears to be impossible; this distribution is supposed to be due to the frequent cleistogamy and perhaps to apomixis; therefore any attempt to subdivide systematically the group leads to divide as far as to pure line, or to clone. On this basis it is proposed to consider the complex of diploid forms as a single taxonomic unit.