This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
This is not known in early deposits, though Zostera-like foliage occurs in estuarine deposits, but it is found in plant beds in S. Sweden in Gothland. To-day its distribution is around the North Temperate and Arctic coasts. In Great Britain it is absent from the coast of N. Devon, Cardigan, Merioneth, Denbigh, Flint, Westmorland, Dumfries, Berwick, Aberdeen, Banff, Mid Ebudes, but is generally distributed elsewhere, around the coast of other maritime counties, as far north as the Shetlands, and in Ireland and the Channel Islands.
This is one of the few marine, aquatic plants which grow in salt water at low-water mark, and they are typical of the flora of estuaries, and coasts which exhibit numerous small bays and inlets, especially on sandy and muddy coasts.
The habit is that of a submerged, streaming- sea-weed. The leaves are grass-like, borne on flattened or nearly round stems, and are long, lance-shaped, wavy, blunt, with 1-7 nerves, bright green, and entire. The first Greek name indicates their ribbon-like character.
The flowers are green, enclosed in a spathe or sheath which is like a hollowed-out leaf, on a long, stout flower-stalk, like the leaves, enclosing a spadix with anthers and an ovary, in two series, opposite, the ovary alternating with the stamens, and stalkless. The capsule contains 1 ribbed seed, and is furrowed, and the seed milky-white. The spadix is not banded and contains many flowers. The top of the spathe exceeds the spadix. There is no extine in the pollen.
Grass Wrack is 1-3 ft. long. It flowers in August and September. Grass Wrack is perennial and propagated by seeds.
Photo. A. R. Horwood - Grass Wrack (Zostera marina, L.)
The stamens with 2 half-anthers and the carpels with 2 stigmas are borne in two rows on a spadix enclosed in a spathe. The flowers are submerged. The pollen tubes are long thread-like bodies, which float in sea water at any depth, having the same specific gravity. The hairlike stigmas being large and projecting easily catch some of the threads, and are pollinated in this way by water as trees are by the wind.
The fruit is an achene, which is furrowed, and the plant being immersed the seeds are dispersed by water.
This species is aquatic and confined to sea water.
A beetle, Haemonia Curtisi, is found on it.
Zostera, Linnaeus, is from the Greek zoster, girdle, in allusion to the long strap-shaped, streaming leaves. The meaning of the specific name is obvious.
Grass Wrack is also called Barnacle-grass, Drew, Sweet Grass, Grass-weed, Mallow, Sleech, Widgeon Grass, and Sea Wrack. Another name is Bellware, this plant being the "Seaweed" from which kelp is made.
The leaves are used as manure in Sweden and Holland, and used for stuffing packing-cases, beds, and cushions, being flexible. It is used for the covering of liqueur flasks. It is also employed for thatching, roofs thus made lasting over 100 years. Grass Wrack is also used for packing glass and china.
Essential Specific Characters: 317. Zostera marina, L. - Leaves broadly linear, veined, submerged, flower in spadix, fruit a nut.