In introducing it where it is scarce, to transplant it successfully large sods containing the strong creeping roots must be dug up, and planted in light soil; if peaty, so much the better.
Some of the stones and sods on which it grows look as if sown with a mixture of gold and the material that forms the wings of green humming-birds.
It was supposed to require a particular kind of rock, but its wonderful coruscations have lately been seen to spread over sods of turf and masses of peat, as well as over chips of rock brought from its native place.
An ancient writer states that the rampart was built of regularly laid sods (the same method which had probably been employed by Hadrian), and excavations in 1891-1893 have verified the statement.
Thirdly, nowhere very clear on the surface and as yet detected only at a few points, there are the remains of the " turf wall," constructed of sods laid in regular courses, with a ditch in front.