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Sesuvium portulacastrum (L.) L. 1759
pronounced: sess-OO-vee-um port-yoo-luh-KASS-trum
(Aizoaceae – the fig-marigold family)
common names: Sea Purslane, Shoreline Purslane
Sesuvium means ‘from the area inhabited by the Sesuvii’. These were members of a Gallic tribe mentioned by Julius Caesar; but the application to this plant is obscure. Portulacastrum is from the Latin word portulaca, the purslane – botanical Latin for ‘like portulaca’. Purslane, formerly spelt purslain, comes via the Old French porcelaine, which in turn came from porcilaca, the word Pliny the Elder used for portulaca.
This is a perennial herb that grows in coastal areas throughout much of the world. The plants pictured grow on the salt flats of Cockle Bay. A small colony has also recently (December 2014) appeared on the Picnic Bay beach. The plant was first published as Portulaca portulacastrum by Linnaeus in 1753. Six years later he transferred it into Sesuvium, and there it has remained ever since, although in 1891 Otto Kuntze unsuccessfully tried to transfer it into a new genus as Halimus portulacastrum. It grows in sandy clay, coastal limestone and sandstone, on tidal flats and salt marshes. Native to Africa, Asia, Australia and the Americas, it has naturalized in many places where it is not indigenous.
It is a succulent herb with roots at the nodes, with a prostrate and sprawling growth habit. Its leaves are opposite, glossy, flat, strap-like and around 2.5–5 cm long. They are mostly lanceolate, flat below and slightly concave above, with blunt or rounded tips. The base of each leaf clasps the stem, and the leaf bases of paired leaves touch each other.
The thick, smooth stems can be up to 100 cm long, and can range in colour from green through to red and orange. The roots at the nodes help to anchor the plant in the mud or the sand.
The flowers are pink or purple, about 1 cm long, with 5 petals, and are usually solitary on stalks about 1 cm long in the leaf axils. It flowers through most of the year.
Sea purslane is a pioneer sand-colonizing plant and will grow readily on the upper beach and the seaward slope of the frontal dune or beach ridge. It is very salt-tolerant and will grow on the beach along the debris line. It traps and holds wind-blown sand and tends to form small hummocks. It cannot withstand excessive sand-blast, and seldom survives complete burial under wind-blown sand.
It does grow well in protected situations on the crest and landward slope of the frontal dune, and can be included in dune revegetation programmes. The plant can be propagated from rooted stem cuttings taken from established plants. The cuttings can be planted at 1–2 m centres on the seaward slope and crest of the frontal dune or beach ridge. When other vegetation is present, the distance between plants can be greater.
The caterpillars of the Beet Webworm Spoladea recurvalis feed on the plant.
Photographs taken at Cockle Bay 2010, 2014 and Picnic Bay 2014
Page last updated 21st February 2018