German lawn rush

The German lawn rush (Trichophorum cespitosum subsp. germanicum) is a subspecies of the lawn rush genus (Trichophorum cespitosum) within the acid grass family (Cyperaceae).[1] It is a characteristic plant of nutrient-poor moors, wet and moor heaths and moor forests. The mostly hedgehog-shaped form of its tufts is characteristic.

Description

Vegetative characteristics

The German lawn rush is a perennial, herbaceous plant that grows to a height of 5 to 60 centimetres. This hemicryptophyte forms small to medium-sized, dense, rigid clumps, which in turn can form dense turfs; no runners are formed. The base of the stem is roundish to triangular-roundish. The basal leaf sheaths are leathery brown and shiny. The stems grow rigidly upright or diagonally upwards, sometimes bent over at fruiting time. The stems are round in cross-section, smooth and green to dark green.

The leaf sheaths of the lower leaves are usually without leaf blades. The uppermost leaf sheath is cut off at an angle and is more than 2 millimeters deep at the base of the leaf blade. The 1 millimeter wide uppermost leaf blade is about twice as long as the cut-out is deep (see picture on the left). The ligules are very short.

Generative features

The flowering period ranges from May to July, rarely later.[2] The one or two bracts are similar to the glumes and are about as long as the inflorescence. The inflorescence consists of a single, terminal, erect spikelet. With a length of 5 to 10 millimeters, the spikelets are obovate or elongated to club-shaped and contain three to twenty flowers. The flowers contain three stamens and three stigmas.

The main axis of the spikelets, the spikelet rachis, is about 3 millimeters long after the fruit has fallen off. The glumes are elongated lanceolate, pointed, 3 to 4 millimeters long, yellow to reddish-brown, with a green keel and membranous edge. The five to six perianth bristles (perigone) are usually significantly longer than the fruit.

The caryopsis, which is grey to yellow-brown when ripe, is flattened triangular at a length of 1.5 to 2 millimeters and narrows towards the upper end.

The number of chromosomes is 2n = 104[3].

Possibilities of confusion

Rasenbinsen (Trichophorum) sind generell in der äußeren Gestalt den Sumpfbinsen (Eleocharis) ähnlich. Sie besitzen jedoch im Gegensatz zu diesen eine deutliche, wenn auch kurze Blattspreite an der obersten Blattscheide.

Sehr ähnlich ist die Gewöhnliche Rasenbinse (Trichophorum cespitosum subsp. cespitosum). Ihre oberste Blattscheide ist gegenüber dem Ansatz der Blattspreite nur etwa 1 Millimeter tief ausgerandet. Die oberste Blattspreite ist etwa fünfmal so lang wie der Ausschnitt tief ist. Das endständige Ährchen ist 5 bis 6 Millimeter lang; die Ährchenspindeln sind nach dem Abfallen der Früchte 2 Millimeter lang oder länger.

Distribution

Die Deutsche Rasenbinse kommt ausschließlich im Westen Europas[1], namentlich in Portugal, Spanien, Frankreich, Belgien, den Niederlanden, Deutschland, Dänemark (inkl. Färöer), Großbritannien (einschließlich Shetland-Inseln und Hebriden), Irland, Norwegen und Schweden vor. Sie wird nach Süden, Norden und Osten durch die Gewöhnliche Rasenbinse ersetzt.[4]

Ihr Gesamtareal wird mit 100.000 bis eine Million km² angegeben. Der Arealanteil in Deutschland beträgt 10 bis 33 Prozent. Hier ist sie im Nordschwarzwald, im Harz und im Norddeutschen Tiefland nachgewiesen. Die Bundesrepublik stellt den südöstlich äußeren Rand ihres kontinuierlich besiedelten Areals dar.

Site conditions

The German lawn rush is a light plant; it grows optimally in full light and only tolerates shade to a limited extent. Its ecological focus is on wet, partially flooded, highly acidic, very low-nitrogen moorland soils and peat bogs. It is not saline. It is also a moderate heat indicator. The German rush is mainly found in submontane-temperate areas of western Europe with an oceanic climate. Its ecological behavior can be classified according to the Ellenberg indicator values as follows: L-8, T-5, K-2, F-9, R-1, N-1, S-0.[5]

The ecological indicator values according to Landolt et al. 2010 in Switzerland are: moisture index F = 4w+ (very moist but highly variable), light index L = 4 (bright), reaction index R = 1 (highly acidic), temperature index T = 3 (montane), nutrient index N = 1 (very nutrient-poor), continentality index K = 1 (oceanic)[6].

The German lawn rush is a so-called competitive stress strategist. Plant taxa in this group are perennial, highly competitive species on sites with at least one minimum or maximum ecological factor (stress). These include, for example, marsh plants, plants in dry locations or tall mountain plants, which can cope with the extreme conditions of their locations and thus have a competitive advantage over other plants[7].

An effective internal nutrient cycle is characteristic of the German lawn rush - and many other raised bog plants. The nutrients required to build up the above-ground parts of the plant are transferred back to the base of the shoot during seed formation. In the following vegetation period, this supply can be mobilized without losses. Furthermore, intensive rooting of the upper soil layers and the very closely spaced plant specimens prevent nutrients from dead plant parts from being washed out[8].

Ecology

The German lawn rush forms a so-called mycorrhiza with fungi.[3] This symbiosis allows it to better absorb the scarce soil nutrients. The German lawn rush is wind-blooming (anemophilous) and its seeds are also spread by the wind (anemochory).

Socialization

From a phytosociological point of view, the German rush is the characteristic species of the association Sphagno compacti-Trichophoretum germanici (Oberd. 1938) Bartsch 1940 em. Dierßen 1975 (in German: Rasenbinsen-Anmoor)[9] within the bell heath-wet heath communities (association Ericion tetralicis). Characteristic species of these plant communities are peat mosses such as Sphagnum compactum, Sphagnum tenellum, bell heather (Erica tetralix), yellow bog lily (Narthecium ossifragum), narrow-leaved cotton grass (Eriophorum angustifolium), blue moor grass (Molinia caerulea) and bog birch (Betula pubescens). Other heather plants such as common cranberry (Vaccinium oxycoccos), bilberry and bilberry (Vaccinium uliginosum, Vaccinium myrtillus) and sheath cottongrass (Eriophorum vaginatum) are constant companions[10].

Etymology of the scientific name

The genus name Trichophorum goes back etymologically to the fruiting stem, which is covered with a fine tuft of woolly hairs after ripening, and is derived from the ancient Greek words thríx, genitive trichós and Greek -phóros. However, only the alpine grass (Trichophorum alpinum) has such a "woolly head" (peristome) and shows the close relationship to the genus of cotton grasses (Eriophorum). In the other species of the genus Trichophorum, the perianth is reduced to fine bristles. Artepithetum cespitosum comes from the Latin caespēs gen. caespitis and is translated as "turf-forming". The name for the subspecies germanicum is ultimately derived from the area of Germany[11].

Hazard and protection

The German rush is not endangered throughout Europe and enjoys no special legal protection. In Germany, however, it is classified as "endangered" (endangerment category 3). In Hamburg and Mecklenburg-Western Pomerania, the German lawn rush is classified as "threatened with extinction" (endangerment category 1). In Brandenburg and Berlin, it is now "extinct" (endangerment category 0).

In north-western Germany, the German rush has declined sharply, particularly due to the cultivation of moorland heaths. Larger populations now only grow in some nature reserves; small remnants can usually still be found along forest paths and edges in areas of afforested heathland[12].

Sources and further information

References

Weblinks

Commons: German lawn rush (Trichophorum cespitosum) - Collection of images, videos and audio files

German lawn rush. on FloraWeb.de
Profile and distribution map for Bavaria. In: Botanical information node of Bavaria.
Distribution in the northern hemisphere.

User:TiagoOT/sandbox