A perennial herb of dry base-rich rock faces, cliffs and ledges, close-grazed calcareous grassland and, occasionally, river shingle. It is a pseudogamous apomict, reproducing mostly by seed, with very limited vegetative spread. Generally montane, reaching 1065 m on Ben Lawers (Mid Perth), but descending to 250 m in Assynt (W. Sutherland).
Although some sites were lost before 1930, the distribution of this species seems to have been stable in recent years. Unlike P. neumanniana, British populations of P. crantzii are relatively homogeneous.
Eurosiberian Boreo-arctic Montane element; also in N. America.
Light (Ellenberg): 8
Moisture (Ellenberg): 5
Reaction (Ellenberg): 8
Nitrogen (Ellenberg): 2
Salt Tolerance (Ellenberg): 0
January Mean Temperature (Celsius): 0.7
July Mean Temperature (Celsius): 12
Annual Precipitation (mm): 1855
Height (cm): 20
Perennation - primary
Life Form - primary
Clonality - primary
Count of 10km squares in Great Britain: 98
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: -0.21
Scarce Atlas Account
Potentilla crantzii (Crantz) G. Beck ex Fritsch
P. crantzii is a calcicolous mountain plant of steep, dry rock faces and ledges, growing on a wide range of basic rocks, on both shady and sun-exposed aspects. Its associated plants on cliffs include Alchemilla alpina, Dryas octopetala, Galium boreale, Linum catharticum, Persicaria vivipara, Saxifraga aizoides, S. oppositifolia and Silene acaulis. It also grows in close-grazed calcareous grassland, often on slopes below the crags, but also on level ground. Here it may be subjected to rabbit grazing, especially at the lower altitude sites (Raven & Walters 1956). P. crantzii reaches 1000 metres in Snowdonia and 1035 metres on Ben Alder, but descends to 300 metres in northern England and 250 metres in Assynt.
P. crantzii is a perennial. Colonies consist of discrete individuals which apparently arise from seed. Vegetative spread is very limited. The plant is a pseudogamous apomict: the flowers are pollinated mainly by hover-flies, but the pollen only stimulates the formation of seed.
There is little evidence that the distribution of this species has changed in recent years, and colonies appear to show little variation in size from year to year. Heavy grazing is a threat to populations in accessible situations.
P. crantzii has a typical arctic-alpine distribution. It is almost circumpolar but it is missing from the lands on either side or the Bering Straits.
Unlike those of P. neumanniana, British populations of P. crantzii are relatively homogeneous, although both hexaploids and heptaploids occur (Smith 1963b; Smith 1971).