Seapurslane thrives in tidal flats and on fore dunes down to the high tide line. Rooting at the nodes, it forms a mat of stems and leaves where it traps sand grains and contributes to land building. When dunes are stabilized, other plants can take hold to build soil.

Seapurslane is a halophyte, a plant that tolerates, even flourishes, where the water has concentrations of salt greater than a half percent. The ions of sodium (Na+) and chlorine (Cl-) interfere with cellular processes and are fatal to most plants. Seapurslane avoids problems by storing the ions away in a vacuole, a flexible bag-like structure within each cell.

Separating the salt from cellular processes is not the only adaptation to the harsh climate of the seaside. Seapurslane is tailored to be a thrifty plant; it has to be in order to survive. In addition to salt spray and sea water, tidal flats and fore dunes are subject to drying winds, strong sunlight and heat.

Seapurslane hugs the ground where wind is less severe. The succulent leaves photosynthesize by the C4 process which requires an extra step in fixing the carbon dioxide, but prevents oxidation (and loss of energy) during extreme heat.

Even the flowers are thrifty. Water wasting petals are missing; the upper side of the calyx (the sepals collectively) is colored pink to purple. The flower packs most of its splendor into its 30 stamens for once it opens there must be plenty of pollen to attract foraging insects and insure pollination. The flower must close after a few hours and put the remainder of its energy into producing up to 60 tiny black seeds.

 

(Compiled from: “3. Sesuvium portulacastrum”, Flora of North America, Volume 4, pg 81, eFloras.org; “Sesuvium portulacastrum”, Edward F. Gilman, Fact Sheet FPS-548, Cooperative Extension Service, IFAS, University of Florida, October 1999; “Aizoaceae”, Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 1st June 2007.)