MORPHOMETRIC VARIATIONS OF FIVE TIDAL MARSH HALOPHYTES ALONG ENVIRONMENTAL GRADIENTS

Morphological characteristics of Deschampsia cespitosa, Grindelia integrifolia, Distichlis spicata, Jaumea carnosa, and Salicornia virginica varied significantly along transects between the upper and lower portions of an Oregon salt marsh. Plant height, height of the flowering shoot, leaf number and width, internode length, branching, and stem diameter varied with position in the marsh. Anatomical differences in stem structure were also obvious. Lignification of vascular bundles of D. spicata, the amount of secondary xylem in G. integrifolia, and vascular bundle size in J. carnosa were greatest in the upper marsh zone. The quantity of aerenchymatous tissue in S. virginica was greatest at the lower, wetter end of the transect. Reproductive effort was greatest at the upper distributional limit of G. integrifolia and D. spicata while greatest in J. carnosa at its lower limit. Soil moisture and soil chemical data were collected to relate morphometric variation to environmental parameters. Differences in plant structure may have application as an aid in determining wetland boundaries.