Salt marshes are challenging habitats for plants and the plants that thrive their have unusual adaptations, making them fascinating subjects of study. Here we review a few such species growing together as a single community on a single salt marsh. This is the second part of this article, the first part covered glassworts.
Greater Sea-spurrey (Campion Family, Caryophyllaceae)The Greater Sea-Spurrey (Spergularia media) has striking, though very small (8 to 12 mm across) pinkish-white flowers (the camera has made them look whiter than in life but a pink tinge is visible). In Greater Sea-spurrey, the stems are creeping to ascending and up to 30 cm long. This species is perennial. The leaves are fleshy and somewhat succulent.
fruit is a capsule which opens via three valves.
Suaeda maritima (Chenopodiaceae) is an annual salt-marsh plant with succulent leaves (like half cylinders) with pointed tips and slightly tapered bases. (The related perennial Shrubby sea-blite, Suaeda vera (Suaeda fruticosa) is larger and has more cylindrical leaves with rounded tips and less tapered bases). The stems are either green or flushed red and may be upright or prostrate.
Below: a series of three close-up photomicrographs in different focal planes. Note the 5 fleshy sepals on each flower.
Annual Sea-blite growing among glassworts and Sea Purslane.
This plant is a perennial (unlike other Oraches) and is a low shrub with a mealy appearance. The bracteoles enclose the female flowers and developing fruits and have broad 3-lobed tips and are fused together over much of their length (protecting the sexual parts from dehydration).
Sea Beet is similar in superficial appearance to a Goosefoot or an Orache, with spikes of fairly inconspicuous and dull-coloured flowers. However, The flowers are more conspicuous to the naked eye with the 5 fleshy sepals quite distinct. The coastal form is usually subspecies maritimum. The cultivated form, which produces the swollen taproot that is eaten as beetroot, is subspecies vulgaris, which can sometimes also be found growing wild along coasts.
Above: Sea Beet growing in a different location (on a sea wall). The seaside plant is usually subspecies maritima, though the form cultivated for its root, subspecies vulgaris occurs along coasts as well.Golden Samphire (Inula crithmoides): Asteraceae
Golden Samphire (family: Asteraceae) is found on the upper drier banks of salt marshes (and also on shingle beaches and sea cliffs). Note the fleshy leaves: an adaptation to salty habitats.
The picture below was taken on a coastal promenade rather than a salt marsh; the lilac flowers of Rock Sea-lavendar (Limonium binervosum agg., Plumbaginaceae: the Sea-lavendar family) can also be seen interspersed with the Golden Samphire:
Seaweeds of Salt Marshes
At the base of runnels in the lower salt marsh seaweeds are also to be found, in particular the Bladder Wrack (Fucus vesiculosus) and the Knotted Wrack (Ascophyllum nodusum). Much of the soil on the bottom and sides of the runnels is stained green. Microscopical examination revealed that this was due to an unidentified filamentous green alga, forming chains of cells or filaments one-cell thick, and numerous filaments of blue-green cyanobacteria of the Oscillatoria type (actually prokaryotes). A sample of this green-tinged soil, about 1 square cm and only a few millimeters thick also contained about 30 aquatic oligochaete annelids (Tubificids) each about 1 cm long. This is a phenomenal density, the entire sample of surface soil was a living matrix!
Above: Oscilatoria type cyanobacteria from the bottom of a salt marsh runnel.
Exercise: How many plants can you identify below?Click images to view full size.
Bibliography and Further Reading
Davy, A.J., G.F. Bishop, H. Mossman, S. Redondo-Gomez, J.M. Castillo, E.M. Castellanos, T. Luque and M.E. Figueroa, 2006. Biological Flora of the British Isles: Sarcocornia perennis (Miller) A.J. Scott. Journal of Ecology 94: 1035-1048.
Mozafar, A. and Goodin, J.R. 1970. Vesiculated Hairs: A Mechanism for Salt Tolerance in Atriplex halimus L. Plant Physiol. 45: 62-65.
Telenius, A. 1992. Seed heteromorphism in a population of Spergularia media in relation to the
ambient vegetation density. Plant Biology 41: 305-318.
Telenius, A. and P. Torstensson, 1989. The seed dimorphism of of Spergularia marina in relation to dispersal by wind and water. Oceologia 80: 206-210.
Article created: 13 Sep 2016
Article updated: 15 Sep 2018
Article updated: 14 Sep 2019 (determinations of glassworts revised)
Article updated: 2/11/2019
Article updated: 14/12/2019