Sporobolus virginicus (L.) Kunth. Var. Minor Bailey is a creeping perennial grass of coastal areas around Australia. Along the N.S.W. coast it forms a polyploidy complex with, to-date, only tetraploid populations being observed north of Jervis Bay (Smith-White, 1979). The species spreads by vigorous vegetation growth of stolons and rhizomes and in tetraploid wariety minor, the development of viable pollen (Smith-White, 1979), suggests that sexual reproduction is also an important factor in establishment and survival of this cytotype.
Preferred habitats of tetraploid plants are either tidal salt marshes or river banks within the range of tidal movement. In such places the extent of its distribution is significantly influenced by topography. Rapid changes in elevation, such as river banks, produce very narrow disjunctive zones. In areas where the land surface is almost flat, as is common in salt marshes in eastern Australia, Sporobolus forms wide dominant zones and is often present as a sub-dominant in neighbouring vegetation zones. This correlation of distribution to elevation above tidal water directly reflects the gradient in soil salinity (Clarke and Hannon, 1967). As well, some phenotypic characters respond plastically and can be correlated with the salinity of the soil (Smith – White, 1977). In the higher salinity zone, such as the Sarcocornia quinqueflora zone, leaf blades are short as are intermode distances. Gradual decreases in soil salinity across the zone produce gradual change in phenotype. The tussocky habit of clones usually persists into the seaward edge of the Juncus kraussii zone, above which tillers too long to support themselves take on a decumbent habit.
How to Cite:
Smith-White, A.R., 2010. Physiological differentiation in a salt-marsh grass. Wetlands Australia, 1(1), p.20. DOI: http://doi.org/10.31646/wa.49