Technical Abstract: Breeding populations of the dwarf saltwort (Salicornia bigelovii Torr. [Chenopodiaceae]) have been evaluated under high seawater salinity (45 dS m-1) for phenotypic, morphometric, biomass and seed traits in an effort to select suitable families and genotypes within families for breeding purposes and to develop genotypes for biomass, seed, and vegetable production using sea and brackish water and marginal coastal land resources. Univariate and multivariate statistical analyses were employed to study the genetic variation and trait relationships among and within populations. The largest variation between populations was found for harvest index and the smallest for number of spikes per plant; however, a more complex structure of variance was found when fixed and random factors were considered. Multivariate relationships between and within architectural and fitness-related traits suggest that biomass and seed yield gains can be achieved by manipulating plant architecture. Discriminant analyses between populations resulted in populations being correctly (mean 83%) classified, and the partial least squares regression modeling predicted seed yield (R2=0.65; p<0.02) more accurately than plant dry weight (R2=0.46; p<0.05). We identified populations and families within populations with favorable combinations of phenotypic and morphometric traits that are suitable for the development of Salicornia varieties for biomass, seed, or green vegetable production.