It is one of the hardiest and best of the known kinds.
It is a variable plant, spread over nearly half the world, the hardiest forms coming from Chili, New Zealand, and Tasmania.
The hardiest of the other species are P. parviflorum, littorale, and rotatum, but these only succeed on warm soils in mild localities, and are best in a frame or a cool greenhouse.
As soon as the stock has been kept a sufficient time to pass through all the ordinary extremes of climate, a number of the hardiest may be removed to the more remote station, and the same process gone through, giving protection if necessary while the stock is being increased, but as soon as a large number of healthy individuals are produced, subjecting them to all the vicissitudes of the climate.
The Herdwick is the hardiest of all the breeds thriving upon the poor mountain land in Cumberland and Westmorland.