Ecological Adaptations of Salt Marsh Grass, Distichlis Spicata (Gramineae), and Environmental Factors Affecting Its Growth and Distribution

Abstract

Salt grass is an important pioneer plant in early stages of succession. The sharp-pointed rhizomes with numerous epidermal silica cells, and the aerenchymatous network of the rhizome, leaf sheath, and roots facilitate development of the plant in heavy clays, shales, and inundated soils. In salt marshes of southern Utah, salt grass contributes to a hummock-building process that favors localized removal of salts by capillary action and evaporation. This process provides a narrow strip of soil that is favorable for the rooting of extended rhizomes. In laboratory experiments, maximum growth for Disticlilis spicata, a perennial salt marsh grass, was obtained at 15,000 ppm soluble salts in nutrient solution cultures. Comparable concentrations of salts occurred in soils of the habitat from which plants were taken. Nearly equal concentrations of sodium and potassium were found in the plant tissue where the growth of the plants was optimal; such a ratio was maintained in the plants during most of the growing season. In the field the greatest amount of growth of salt grass takes place when temperatures are cool and soil moisture is quite high during the early spring. During mid-summer as air temperatures rise, crude protein in the plant decreases. During periods of high salt and water stress, morphological and anatomical adaptations of the stomata, salt glands, and trichomes of salt grass are important for survival. Stomata on exposed ridges of vascular bundles, where desiccation is greatest, usually are covered by four epidermal cells. In contrast, stomata found in the grooves between vascular bundles tend to be uncovered. The salt gland is composed of a large basal cell and a cap cell and actively excretes (in a diurnal rhythm) excess sodium, potassium, and chloride ions. A mechanism for salt excretion from this gland is postulated. The silica-containing trichomes on the leaves may playa role in cooling the leaf under conditions of high solar radiation and also serve to protect the plant against attack by herbivores. 635

Ecophysiology of salt excretion in the xero‐halophyte Reaumuria hirtella

“…Further increase in concentration of NaCl caused an obvious decrease in the amount of secreted fluid (Batanouny, Hassan & Fahmy, 1992). Hansen et al (1976) measured salt secretion of Distichlis spicata by the rinsing method, and recorded a diurnal rhythm with more salts being secreted during the night. By contrast, Scholander et al (1962) and Hill & Hill (1976) concluded that the daily changes in the secretion rates seemed to follow the diurnal rhythm of transpiration.…”

Silicon location through backscattered electron imaging and X-ray microanalysis in leaves of Cyperus ligularis L. and Rhynchospora aberrans C. B. Clarke (Cyperaceae)

“…al. 1959) and herbivores (Hansen et al 1976;Hunt et al 2008). Also, depending on the type and location of deposition, it is an important taxonomic characteristic (Metcalfe 1969;Dahlgreen & Cliff ord 1982).…”

Respuestas morfológicas y anatómicas de Tessaria absinthioides (Hook. et Arn.) DC. a la salinidad

“…Hansen et al (1976) observaron esta característica en plantas de Distichlis que crecieron en suelos saturados.…”

“…Se observa un gran aumento de la pubescencia en hoja a -0,4 MPa, conjuntamente con el aumento del número de lagunas en la corteza de la raíz y el aumento relativo de la corteza del tallo. Estos efectos son característicos de medios desecantes (Fahn 1974, Hansen et al 1976. Quizás esta sal le produce mayor perjuicio al vegetal y como resultado un efecto haloxeromórfico.…”