molinia caerulea
{{Short description|Species of grass}}
{{Speciesbox
|name = Purple moor-grass
|image = Molinia.jpg
|image_caption = Habitus
|genus = Molinia
|species = caerulea
|synonyms = Aira caerulea
}}
Molinia caerulea, known by the common name purple moor-grass,{{BSBI 2007 |access-date=2014-10-17}} is a species of grass that is native to Europe, west Asia, and north Africa. It grows in locations from the lowlands up to {{convert|2300|m|ft|0|abbr=on}} in the Alps. Like most grasses, it grows best in acid soils, ideally pH values of between 3.5 and 5, however, it can continue to live under more extreme conditions, sometimes to as low as 2. It is common on moist heathland, bogs and moorland throughout Great Britain and Ireland. Introduced populations exist in northeastern and northwestern North America.{{citation|url=http://plants.usda.gov/java/profile?symbol=MOCA2|title=Molinia caerulea (L.) Moench }}
The specific epithet caerulea means "deep blue"{{cite book|last=Harrison|first=Lorraine|title=RHS Latin for gardeners|year=2012|publisher=Mitchell Beazley|location=United Kingdom|isbn=9781845337315|page=224}} and refers to the purple spikelets.
Description
Molinia caerulea is a perennial herbaceous bunchgrass (tussock-forming), growing up to {{convert|120|cm|0|abbr=on}} tall (taller when sheltered by gorse and heather), with many closely packed stems. The leaves are coarse, green, taper to a point, long, flat and sometimes slightly hairy on top.{{cite book |author=C. E. Hubbard |author-link=Charles Edward Hubbard |year=1978 |title=Grasses: a Guide to their Structure, Identification, Uses and Distribution in the British Isles |edition=2nd |publisher=Penguin Books |url=https://archive.org/details/grassesguidetoth0000cehu/page/466/mode/2up |page=351}} Due to the dense tussock it is very resistant to heath fires. Its ligule is a ring of hairs, as in heath grass (Danthonia decumbens). The long narrow purple spikelets are a major identification feature – the panicle is {{convert|15|cm|0|abbr=on}} long.{{cite book |last1=Cope |first1=Tom |last2=Gray |first2=Alan |title=Grasses of the British Isles |date=2009 |publisher=Botanical Society of the British Isles |location=London}}
It flowers between July and September, later than any other species.
Ecology
The caterpillars of some Lepidoptera use it as a foodplant, e.g., the chequered skipper (Carterocephalus palaemon).
Claviceps purpurea is an ascomycetous fungus which grows on the seeds of purple moor grass.
Purple moor grass and rush pastures were a United Kingdom Biodiversity Action Plan habitat, on account of their rarity.{{cite report|editor=Ant Maddock|title=Purple moor grass and rush pastures|publisher=UK Biodiversity Action Plan - Plan Priority Habitat Descriptions| date=2008| url=https://data.jncc.gov.uk/data/6fe22f18-fff7-4974-b333-03b0ad819b88/UKBAP-BAPHabitats-43-PurpleMoorGrass.pdf}} Originally published in volume=II: Action Plans, Tranche 1, Vol 2, p253, 1995, reviewed in 2007.
However, in 2025 it was reported that purple moor grass was spreading over Britain and displacing other vegetation in a way characteristic of invasive species, although it is native. Over the previous fifty years it had spread over large upland areas in much of Wales, Dartmoor, Exmoor, the Pennines, the Peak District, North York Moors, Yorkshire Dales and many parts of Scotland. Areas of moor grass support very little bird or insect life – a characteristic described as a "terrestrial dead zone" or desert – and is difficult for humans to walk through. It is not controlled by herbivores, who will favour other plant species over the grass and will not eat it whatsoever past early summer, when its nutritional value falls heavily. It is also unaffected by disease and the natural successional processes through which grassland typically transitions to other plant communities, such as temperate rainforest.{{cite news| last=Monbiot | first=George | author-link=George Monbiot |publisher=The Guardian | date=9 June 2025 | url=https://www.theguardian.com/commentisfree/2025/jun/09/britain-deserts-dead-zones-purple-moor-grass |title=There's an invader turning huge swathes of Britain into deserts – and these dead zones are spreading}}
The cause of the spread is largely human activity: incentives to farmers to raise livestock, and the burning of moorland to produce fresh vegetation for animals, have pushed many environments where Molinia now dominates beyond their capacity to sustain a natural ecological balance. The heavy deposition of nitrogen, which accumulates in rainfall from livestock farming, traffic and industrial sources, and the drainage of naturally-wet peat bogs also contributes. Molinia{{'s}} deep roots protect it from the burning that destroys other, competing, plant species. Most approaches to destroy the invasive Molinia—burning, weedkiller, livestock grazing—only work temporarily, with the moor grass recolonising cleared areas. Approaches such as blocking land drainage to restore its moisture levels, planting sphagnum moss to restore peat bogs, planting trees and excluding livestock are being trialled to combat the issue and restore areas overtaken by Molinia.
Cultivation
Molinia caerulea is cultivated for its panicles of purple spikelets on yellow stems. In cultivation it grows to {{convert|1.5|m|ft|0|abbr=on}} tall by {{convert|40|cm|0|abbr=on}} broad.{{cite book|title=RHS A-Z encyclopedia of garden plants|year=2008|publisher=Dorling Kindersley|location=United Kingdom|isbn=978-1405332965|page=1136}} Numerous cultivars have been selected, of which the following have gained the Royal Horticultural Society's Award of Garden Merit:{{cite web|url=https://www.rhs.org.uk/plants/pdfs/agm-lists/agm-ornamentals.pdf|title=AGM Plants - Ornamental|date=July 2017|page=65|publisher=Royal Horticultural Society|access-date=4 April 2018}}
- M. caerulea subsp. arundinacea 'Windspiel'{{cite web
|url=https://www.rhs.org.uk/Plants/78820/i-Molinia-caerulea-i-subsp-i-arundinacea-i-Windspiel/Details
|title=RHS Plantfinder - M. caerulea subsp. arundinacea 'Windspiel'|access-date=4 April 2018}}
- M. caerulea subsp. caerulea 'Edith Dudszus'{{cite web | url = https://www.rhs.org.uk/Plants/81061/Molinia-caerulea-subsp-caerulea-Edith-Dudszus/Details | title = M. caerulea subsp. caerulea 'Edith Dudszus' | publisher = RHS | access-date = 6 January 2021}}
- M. caerulea subsp. caerulea 'Moorhexe'{{cite web
|url=https://www.rhs.org.uk/Plants/47257/i-Molinia-caerulea-i-subsp-i-caerulea-i-Moorhexe/Details
|title=RHS Plantfinder - *M. caerulea subsp. caerulea 'Moorhexe|access-date=4 April 2018}}
- M. caerulea subsp. caerulea 'Poul Petersen'{{cite web | url = https://www.rhs.org.uk/Plants/241096/Molinia-caerulea-subsp-caerulea-Poul-Petersen/Details | title = Molinia caerulea subsp. caerulea 'Poul Petersen' | publisher = RHS | access-date = 6 January 2021}}
- M. caerulea subsp. caerulea 'Variegata'{{cite web|title=RHS Plant Selector - Molinia caerulea subsp. caerulea 'Variegata'|url=http://apps.rhs.org.uk/plantselector/plant?plantid=1288|access-date=24 May 2013}}
Gallery
Image:Illustration_Molinia_caerulea0.jpg
Image:Molinia-caerulea.jpg
Image:Molinia.jpg
Image:Molinia.caerulea.jpg
Image:Molinia.caerulea.2.jpg
Image:Molinia.caerulea.3.jpg
Image:molinia_caerulea.jpeg|Inflorescence
Image:molinia_caerulea_habitus.jpeg|Habitus (German Horst)
Image:molinia_caerulea_blatt.jpeg|Leaf and vegetative parts
Image:Molinia-caerulea-habitat.JPG|Molinia caerulea at natural habitat near Silkeborg, Denmark.
File:Claviceps microcephala.jpg|Sclerotium of Claviceps purpurea which grows on the seeds of purple moor grass.
References
{{Reflist}}
- {{cite book |title=Grasses, Sedges, Rushes and Ferns of Britain and Northern Europe |publisher=Collins |series=Collins Pocket Guides |first1=Richard |last1=Fitter |first2=Alastair |last2=Fitter |first3=Ann |last3=Farrer |date=1984 |isbn=0002191369}}
- {{cite book |last=Rose |first=Frances |date=1974 |title=The Observer's Book of Grasses, Sedges and Rushes |pages=18–19 |publisher=Frederick Warne & Co}}
External links
- {{cite web |title=The Highwayman |first=Alfred |last=Noyes |date=16 September 2021 |url=https://www.poetryfoundation.org/poems/43187/the-highwayman}}
{{commons category|Molinia caerulea}}
{{Taxonbar|from=Q157772}}
Category:Bunchgrasses of Europe
Category:Bunchgrasses of Africa
Category:Flora of North Africa
Category:Flora of Western Asia
Category:Garden plants of Europe
Category:Garden plants of Asia
Category:Garden plants of Africa
Category:Plants described in 1753