Molinia caerulea

Molinia caerulea, known by the common name purple moor-grass,^[1] is a species of grass that is native to Europe, west Asia, and north Africa. It grows in locations from the lowlands up to 2,300 m (7,546 ft) 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.^[2]

Purple moor-grass
Habitus
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Clade:	Commelinids
Order:	Poales
Family:	Poaceae
Genus:	Molinia
Species:	M. caerulea
Binomial name
Molinia caerulea (L.) Moench
Synonyms
Aira caerulea

The specific epithet caerulea means "deep blue"^[3] and refers to the purple spikelets.

Description

Molinia caerulea is a perennial herbaceous bunchgrass (tussock-forming), growing up to 120 cm (47 in) 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.^[4] 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 15 cm (6 in) long.^[5]

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 is a United Kingdom Biodiversity Action Plan habitat, on account of its rarity.^[6]

Cultivation

Molinia caerulea is cultivated for its panicles of purple spikelets on yellow stems. In cultivation it grows to 1.5 m (5 ft) tall by 40 cm (16 in) broad.^[7] Numerous cultivars have been selected, of which the following have gained the Royal Horticultural Society's Award of Garden Merit:^[8]

• M. caerulea subsp. arundinacea 'Windspiel'^[9]
• M. caerulea subsp. caerulea 'Edith Dudszus'^[10]
• M. caerulea subsp. caerulea 'Moorhexe'^[11]
• M. caerulea subsp. caerulea 'Poul Petersen'^[12]
• M. caerulea subsp. caerulea 'Variegata'^[13]

Gallery

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  Inflorescence
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  Habitus (German Horst)
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  Leaf and vegetative parts
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  Molinia caerulea at natural habitat near Silkeborg, Denmark.
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  Sclerotium of Claviceps purpurea which grows on the seeds of purple moor grass.