Ammophila (plant)
Ammophila (synonymous with Psamma P. Beauv.) is a genus of flowering plants consisting of two or three very similar species of grasses. The common names for these grasses include marram grass, bent grass, and beachgrass.[2] These grasses are found almost exclusively on the first line of coastal sand dunes. Their extensive systems of creeping underground stems or rhizomes allow them to thrive under conditions of shifting sands and high winds, and to help stabilize and prevent coastal erosion. Ammophila species are native to the coasts of the North Atlantic Ocean where they are usually the dominant species on sand dunes. Their native range includes few inland regions, with the Great Lakes of North America being the main exception.[3] The genus name Ammophila originates from the Greek words ἄμμος (ámmos), meaning "sand", and φίλος (philos), meaning "friend".
The Ammophila grasses are widely known as examples of xerophytes, plants that can withstand dry conditions. Despite their occurrence on seacoasts, Ammophila grasses are not particularly tolerant of saline soils; they can tolerate a salinity of about 15 g/L (1.5%), which makes them "moderate halophytes".[4]
Ammophila builds coastal sand dunes and thus stabilizes the sand. For this reason, the plants are seen as a useful means of reinforcing sand dunes around the world, and have been introduced far from their native range. Alfred Wiedemann writes that Ammophila arenaria, the European species, "has been introduced into virtually every British colonial settlement within its latitudinal tolerance range, including southeast and southwest Australia, New Zealand, South Africa, the Falkland Islands, and Norfolk Island and has been reported from Argentina and Chile."[5] Ammophila species were introduced in the late 19th century on the Pacific coast of North America as well, and massive, intentional plantings were continued at least through 1960. In essentially all of the locations where they have been introduced, Ammophila plants are now listed as invasive, and costly efforts are underway to eradicate them.[citation needed]
Only two species seem incontrovertible: A. arenaria and A. breviligulata. Two other species have been proposed, and are discussed below.
In Europe, Ammophila arenaria has a coastal distribution, and is the dominant species on sand dunes where it is responsible for stabilising and building the foredune by capturing blown sand and binding it together with the warp and weft of its tough, fibrous rhizome system. Marram grass is strongly associated with two coastal plant community types in the British National Vegetation Classification. In community SD6 (Mobile dune) Ammophila is the dominant species. In the semi-fixed dunes (community SD7), where the quantity of blown sand is declining Ammophila becomes less competitive, and other species, notably Festuca rubra(red fescue) become prominent.
The ability of marram grass to grow on and bind sand makes it a useful plant in the stabilization of coastal dunes and artificial defences on sandy coasts. The usefulness was recognized in the late 18th century.[10][11] On the North Sea coast of Jutland,Denmark, marram grass was traditionally much used for fuel, thatch, cattle fodder (after frost) etc. The use led to sand drift and loss of arable land. Hence, legislation promoting dune stabilization came into force in 1779 and 1792, successively leading to a system of state-supported dune planters overlooked by dune bailiffs. Marram grass was – and still is – propagated by root and shoot cuttings dug up locally and planted into the naked sand in periods of relatively calm and moist weather.
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