This section is from the book "The Gardener V3", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
This family is possessed of the strongest tenacity of life - the generic name implies that; and it is highly interesting on account of the rigidly geometric arrangement in rosettes that the leaves of most of the species take. Their extraordinary power of life renders them very useful for many ornamental purposes that are very desirable, but not by any means generally adopted. Many a stump and block and naked rock might be appropriately garnished with them; and those objects, often inert enough and uninteresting in themselves, but from various circumstances, perhaps, irremovable, would by such adornment become attractive and beautiful; and quaint old trees and ruins may be enriched in their own style by the same means. The natural habitats of the Houseleeks - house-tops, walls, rocks, and generally dry exposed stony or gravelly places - at once suggest their fitness for the uses indicated. They establish themselves easily in such places in nature; and in practice to fix them in any position is a very simple matter, all that is needed to that end being a little clay and horse or cow dung, well mixed, as for use in grafting, on which to stick the offshoots, when, even if the surface is vertical, they maybe left to themselves without any misgivings as to success.
The adaptability of some of the species to another and very different use in flower-gardening has been noticed and taken advantage of by some of our best gardeners recently, and is becoming popular. I allude to the new method of bedding out, in which various Semper-vivums are used to define intricate geometrical figures in beds or borders, the spaces being filled, according to the taste of the parties concerned, with flowering plants, or with plants of different foliage, with a view to the production of contrasts in form or combinations of colour and form; and for defining with precision intricate lines and figures, there is perhaps nothing in the vegetable kingdom more fit than these peculiar plants; but for this purpose they must be used in single rosettes, which entails the necessity of their being overhauled annually in spring, so as to remove all off-sets or young rosettes which would mar the lines. They are as easily cultivated on flat surfaces on the ground-level as on any elevation, and though so well adapted to exist on short commons, do equally well in the richest soil, but it is always well to drain well under them.
An extremely interesting and curious plant. The rosettes are small, composed of oblong sharp-pointed leaves, thickly set on both surfaces with soft, short, glandular hairs. The tips of the leaves are connected by radiating lines of delicate white threads, so interwoven with each other as to suggest the idea that a spider had been at work upon them. The flower-stems rise a few inches high. The flowers are pink, composed of twelve or more spreading petals, and appear in July and August. Native of the Alps and Pyrenees.
The leaves in this species, in small rosettes, are lance-shaped, smooth above and below, but fringed on the margin. Flowers composed of six yellow petals. Height about 6 inches. Native of the Tyrol.
A very handsome species, with broad hemispherical rosettes, composed of oblong, glaucous, brown-tipped leaves, terminating in an abrupt sharp point. Flowers purplish, composed of twelve or more spreading petals, appearing from June till August.
Leaves in rather large rosettes, oblong, with an abrupt sharp point, downy above and below, and fringed with long hairs. Flowers pink, with usually twelve petals, appearing in July and August. Native of the mountains of Tyrol, Carinthia, and Salzbourg.
The rosettes in this are rather small and open in the old ones; very small, close, and globular in the young offsets. Leaves lance-shaped, smooth above and below, but fringed. Flowers yellow, few, but very large; petals more than twelve.
Leaves oblong, acutely pointed, hairy on both sides, and fringed. Flower-stems from 9 inches to 1 foot high. Flowers white, petals six, the tips hairy; appearing in July and August. Native of Italy and Austria.
The rosettes are close and compact. The leaves are oblong, widening somewhat upwards, but terminating in an abrupt sharp point, and fringed. Flower-stems 6 to 9 inches high. Flowers dull rose or purple; petals twelve; appearing in July and August. Native of the Alps.
In this the rosettes are close and compact, composed of oblong, wedge-shaped, sharp-pointed leaves with fringed margins. Flower-stems about 6 inches high. Flowers pale yellow ; petals six, fringed. Native of Germany.
The rosettes are large and hemispherical, composed of oblong lance-shaped leaves, terminating in a sharp rather abrupt point, the margins fringed. Petals twelve or more, pink; appearing in early summer, and continuing late. Native of many countries of Europe, high on mountain-ranges, and not uncommon on walls and house-tops in Britain.