Pattern of morphological variation of Salicornia in North Europe
7 July 2015
Piirainen, MikkoAmong the few available morphological traits in the genus Salicornia L. (Amaranthaceae/Chenopodiaceae), most are extremely variable within species probably due to high levels of plasticity. Making taxonomical determinations of Salicornia is more difficult when these plants lose many of their diagnostic characters upon drying. The study of fresh (or liquid preserved) specimens based on their morphology is thus important in taxonomical studies. This study’s objective was the numerical morphological analyses of Salicornia populations in the Nordic Countries and an adjacent Russian region to ascertain whether taxonomic division of this genus by morphology is feasible. In all, 666 plants were collected for morphometric measurements from 31 localities and 52 populations or subpopulations of the North Sea coasts, Denmark Straits, Baltic Sea, the Norwegian Sea, Barents Sea, and the White Sea areas. For practical reasons, part of the samples was studied fresh, and part preserved in FAA (formal - acetic - alcohol) pending measurements. Data were analyzed by principal components analysis and hierarchical cluster analysis. The main taxonomical division was found between the diploid S. europaea s.lat. and the tetraploid S. procumbens Sm., and was mainly based on fertile segment and flower morphology characteristics. Data also show ecological differences: diploids inhabit the upper part of salt marshes, whereas tetraploids grow in the hydrolittoral zone and are restricted to areas of regular tidal influence. It was not possible to make a morphological distinction between two cryptic species, S. europaea s.str. and S. perennans Willd., within the diploid group in the present study. North Norwegian S. europaea clearly deviated from more southern populations, but taxonomical conclusions based only on morphology were avoided in this study. The division of S. procumbens into two geographical races, the southern subsp. procumbens and the northern subsp. pojarkovae was supported.