In the process of studying the species and its varieties, we discovered a unique taxon of the genus that resembles but differs in having a mostly densely white-strigose stem vestiture (sometimes with spreading trichomes) and tuberculate to muricate nutlets with often whitish tubercles that are, in comparison with typical , larger, with a wider base and more pointed apex, and more densely spaced. We believe this form to be different enough to describe as a new species, . This new species occurs in southwestern North America: in California and Arizona of the United States and in northern Baja California, Mexico.
View Article and Find Full Text PDFWe propose a simple mathematical model to describe the mechanical relaxation of cells within a curved epithelial tissue layer represented by an arbitrary curve in two-dimensional space. This model generalises previous one-dimensional models of flat epithelia to investigate the influence of curvature for mechanical relaxation. We represent the mechanics of a cell body either by straight springs, or by curved springs that follow the curve's shape.
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