Poa glauca

Tracheophyta MagnoliopsidaPoaceaePoaPoa glauca

Ecology

A tufted perennial herb of damp mountain rock faces, open ledges, screes and rocky slopes on calcareous substrates, often with Poa alpina. It is also known as a casual by a disused railway in Cardiganshire. From 305 m on Trotternish, Skye (N. Ebudes) to 1110 m on Lochnagar (S. Aberdeen).

Status

Native

World Distribution

Circumpolar Boreo-arctic Montane element.

Broad Habitats

Light (Ellenberg): 7

Moisture (Ellenberg): 5

Reaction (Ellenberg): 6

Nitrogen (Ellenberg): 3

Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): 1.1

July Mean Temperature (Celsius): 11.6

Annual Precipitation (mm): 2252

Height (cm): 40

Perennation - primary

Perennial

Life Form - primary

Hemicryptophyte

Woodiness

Herbaceous

Clonality - primary

Tussock-forming graminoid, may slowly spread

Count of 10km squares in Great Britain: 62

Count of 10km squares in Ireland: 0

Count of 10km squares in the Channel Isles: 0

Atlas Change Index: -0.48

JNCC Designations

NBNSYS0000002551

Scarce Atlas Account

Scarce Atlas Account: 

Poa glauca Vahl

Glaucous meadow-grass

Status: scarce

 

This is a montane grass confined to steep, open faces of calcareous rock and scree, especially on the Dalradian schists of the central Scottish Highlands, where it grows as scattered small tufts. It is never present in quantity, even in the Highlands, and the more southerly populations are mostly small and highly relict. It does not occur in closed vegetation in Britain, and often grows close to P. alpina, sharing the same associates. The altitudinal range is from 550 metres on the Old Man of Coniston up to 1100 metres on Lochnagar but it is occasionally found washed down at lower latitudes. 

This is a perennial grass. Flowering is quite usual in most localities, but there is no evidence of recent spread and it probably just maintains its scattered populations.

P. glauca appears to be grazing-sensitive, though it would be difficult to distinguish if growing sparsely in turf. Collecting may have reduced some smaller populations, but most of the pre-1970 occurrences probably still survive, and have simply not been re­-sought. There is possible confusion with high altitude forms of P. nemoralis (some formerly distinguished as P. balfourii) which grow in the same habitats.

This is an arctic-alpine, Euro-Siberian and North American plant.

 

D. A. Ratcliffe

Atlas text references

Atlas (380d)
Hultén E, Fries M
1986.  Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
Meusel H, Jäger E, Weinert E
1965.  Vergleichende Chorologie der zentraleuropäischen Flora. Volume 1. 2 vols.
Stewart A, Pearman DA, Preston CD
1994.  Scarce plants in Britain.