Hepatica: is a good choice for the rockery or peat bed as it begins to flower in late winter before the usual spring flowers appear. But Hepatica has a special need; the soil must be kept moist at all times. It thrives best in partial shade, add peat at planting time. Stalked lobed leaves follow the Anemone-like flowers and in time the plants form large and dense clumps. Varieties: The most popular species is H. nobilis (H. triloba). The basic details are height three inches, spread twelve inches, flowering period is February to April. The mauve starry flowers, measuring one inch across, are on short stalks above the tri-lobed leaves. Single and double varieties are available in white (alba), blue, pink or purple. H. transsylvanica (H. angulosa) is similar in appearance but is larger and the leaves are more rounded with scalloped edges. Best of all is the hybrid of these two species (H. media 'Ballardii') with large, pure blue flowers. Site and Soil: Well-drained but damp soil is required and thrives in light shade. Propagation: Divide large clumps in autumn.

Hutchinsia: Chamois Cress is a European alpine, growing wild high up in the Alps and Pyrenees. In early summer clusters of white flowers cover the leaves, but these blooms are much smaller than those borne by its more popular relatives Arabis and Iberis. This easy to grow and hardy alpine can be lost if planted between large rocks, the best place for it is in a trough, raised bed or crevice in a dry wall. Hutchinsia is short lived but it readily self seeds. Varieties: There is a single species, H. alpina. The basic details are height two inches, spread nine inches; flowering period is May to July. The rosette of evergreen leaves gives the plant a tufted appearance. The foliage is dark green, shiny and divided into small leaflets. The short flower stalks appear in profusion and at the top of each one is a crowded one-inch cluster of small, pure white flowers. Each bloom has the usual Crucifer pattern of four petals. The variety brevicaulis (one inch high) is even smaller than the species. Site and Soil: Requires well-drained gritty soil and thrives in sun or light shade. Propagation: Sow seeds as soon as they are ripe.

Hypericum: St. John's Wort grows about eighteen inches high and can be used to clothe a large bare bank, but avoid it like the plague in an average sized rockery, it is highly invasive and will swamp choicer plants. There are a number of dwarf Hypericums, all have large five-petalled flowers with a prominent central boss of stamens. Yellow is the standard colour and the ones listed below make excellent rockery plants. Varieties: The most popular one is H. olympicum, which is almost identical to and frequently sold as H. polyphyllum. The basic details are height six inches, spread twelve inches and the flowering period is from June to August. The variety 'Citrinum' is smaller and bears lemon-yellow flowers. H. coris is an evergreen Heather-like plant (six inches high) which bears yellow star shaped flowers in midsummer. H. reptans and H. trichocaulon bear yellow flowers preceded by red buds. Site and Soil: Any well-drained soil and thrives best in full sun. Propagation: Plant stem cuttings in early summer.

Iberis: Perennial Candytuft is one of the basic ingredients of the rock gardens. The popular forms are evergreen, hardy and easy to grow. In late spring the plant is covered with flat clusters of white flowers. Each has the four-petalled arrangement of the Cabbage family, but there are two long petals and two short ones. Iberis does need room to spread. It is best grown where it can tumble over rocks, spread over paving or grow down a wall. Deadhead regularly in order to extend the flowering period. Varieties: I. Sempervirens (I. Semperflorens) is the popular one attaining a height of nine inches, spread of two feet and flowers from May to June. There is a second flush in autumn if the summer has been warm. The flat clusters of flowers are about two inches across. It is better to grow a named variety rather than the species. 'Snowflake' (ten inches) is considered the best, where space is a problem choose the more compact 'Little Gem' (four inches) or pygmaea (three inches). If you want an unusual Iberis there are I. saxatile (four inches, tiny leaves, white flowers) and I. gibraltarica (nine inches, white or lilac flowers). Site and Soil: Any well-drained soil and thrives in full sun. Propagation: Plant stem cuttings in summer.

Iris: has three erect inner petals ('standards') and three pendant outer petals ('falls'). There may be fleshy hairs on the falls ('beards'). The best-known Irises are the large ones, which grow in the herbaceous border or at the edge of the pond, but there are also some splendid dwarf ones which belong in every rock garden. Varieties: The Bulb group contains such rockery favourites as I. Danfordiae (five inches, yellow flowers in February and March) and I. reticulata (five inches, yellow marked purple flowers in February and March). Best, perhaps is the beautiful blue and gold I. Histrioides 'Major'. The Rhizomatous/Fibrous-rooted group has a wide variety of heights and colours. Included here are the hybrids of the bearded I. pumila (four to six inches), I. cristata (six inches, purple and gold flowers), I. lacustris (three inches, lilac, yellow and white flowers) and I. innominata (six inches, gold and brown flowers). Site and Soil: Well-drained soil is required, it can be alkaline for the Bulb group but not for the others. Sun requirement depends on the species. Propagation: Depends on the species. Divide bulbs when foliage has died down, divide rhizomes after flowering.

Juniperus: Juniper is the star of the rockery conifers, the low growing types with their tiered branches provide excellent groundcover. Juvenile leaves are Heather-like but adult ones are tiny green scales. The cones are green and berry-like made up of fleshy fused scales. One of the most popular garden Junipers is the Pfitzer (J. media 'Pfitzeriana'), but it is too vigorous for most situations. Varieties: The Spanish Juniper (J. sabina 'Tamariscifolia') is an old favourite, horizontal branches of feathery foliage with an eight to ten foot spread if left unpruned, but only twelve inches high. J. horizontalis is even smaller (height six inches, spread five feet) and the leaves have a distinct bluish tinge. J. communis 'Depressa Aurea' is a two-foot high spreading bush, golden in summer and bronze in winter. There are a number of others which will not exceed three feet when mature. Choose from J. media 'Old Gold' (golden, spreading), J. squamata 'Meyeri' (blue-green, upright with drooping branches) and J. communis 'Compressa' (greyish-green, column-like). Site and Soil: Well-drained acid soil and thrives best in full sun. Propagation: Plant stem cuttings in autumn.

Leontopodium: Edelweiss can be found in every book on rock garden plants and is listed in most alpine catalogues. This is not due to its beauty; many more attractive plants hardly get a mention. The simple reason is the Edelweiss is the symbol of the Alps and their flowers. It is an interesting rather than an attractive plant; greyish-white, flat flower heads are borne on short stalks above the greyish-green leaves. It flourishes quite happily if the site is sunny and well drained. Varieties: You are likely to be offered only a single species, L. alpinum. The basic details are height six inches, spread nine inches; flowering period is June to July. The narrow leaves are hoary on top and densely woolly below. They form a rosette from which the flower stems arise. The curious flower heads are about two inches across with a central group of small, rayless Daisy-like flowers surrounded by a number of long, flannel like bracts. The variety 'Mignon' is recommended more compact and longer living than the species. Site and Soil: Requires well-drained gritty soil in full sun. Propagation: Sow seeds in early spring.

Lewisia: honours Lewis and Clark. They were the first explorers to cross and map America from the Mississippi to the Pacific; this alpine of the Rockies pays tribute to Lewis and the annual Clarkia honours his partner. Lewisia is one of the most colourful of rockery plants, flowers in pink, peach, orange or white with petals which are often striped. Unfortunately it is not easy to keep alive in the rockery as water in the heart of the plant causes it to rot in winter. The answer is to plant Lewisia sideways in a crack or crevice. Varieties: L. cotyledon is the most popular species. The basic details are height twelve inches, spread nine inches; flowering period is May to June. Choose one of the showy hybrids, such as the 'Sunset' strain. The other species are more difficult to grow and are not really reliable outdoors. L. brachycalyx blooms in May and L. rediviva bears two inch wide flowers in June. The aristocrat is L. tweedyi with two inch wide apricot blooms in April and May. Site and Soil: Requires well-drained gritty soil in full sun. Propagation: Sow seeds in early spring.

Linaria: Alpine Toadflax is an eye-catching perennial with Snapdraggon-like flowers. These blooms are generally bicoloured or multicoloured and are borne in clusters along the trailing stems. The leaves, which are borne is whorls die down in winter. The popular species has two key features. The flowering span is long, extending from late spring to early autumn, but the life span of the plant is short, often no more than a couple of years. Varieties: The usual one is L. alpina, which grows wild in the European Alps. It is an attractive creeper growing about five to six inches high, the trailing stems bearing bluish-grey fleshy leaves and forming a neat mat. The flowering season is May to September, each bloom gaily painted in violet and orange. There is a pink (rosea) variety. L. aplina self-seeds readily so there is usually a supply of new plants, another species which produces new plants from self-sown seeds is the yellow flowered L. supina. The brightest Linaria is L. tristis 'Toubkal' with blooms in yellow, red and purple. Site and Soil: Any well-drained garden soil, thrives in full sun. Propagation: Sow seeds or divide clumps in spring.

Linnaea: Twin Flower is a native of the colder areas of Northern Europe and was named is honour of Linnaeus, one of Europe's most renowned naturalists. It is an old favourite which produces a tangled mat of slender stems and rounded evergreen leaves. It spreads quickly and can become invasive, but it is easily kept in check. During the summer months the dainty, bell like flowers appear above the foliage. A good choice if you have a large damp and shady area to cover. Varieties: There is just one species, L. borealis. The basic details are height two inches, spread two feet and flowering period is from May to July. From the prostrate carpet of stems and leaves these flower-stalks appear each one topped by a pair of pale pink flowers, hence the common name. An easy plant if the conditions are right, but a disappointment on a sandy, sunny or chalky site. If you can find it, choose the variety americana, the plant is bigger and less temperamental and the flowers are deeper pink. Site and Soil: Requires moist, humus rich soil in partial shade. Propagation: Sow seeds or plant stem cuttings in spring.

Linum: Perennial Flax are tufted plants with wiry stems which are easy to grow but are usually short lived. They produce their flowers in summer, five petalled and nearly always are yellow or blue. The blooms fade quickly, but there are always more buds to open. The best displays occur in sandy soil and hot weather. The two enemies of Linum are waterlogged soil in winter and slugs in spring. Varieties: L. perenne alpinum is one of the sky blue varieties attaining a height of six inches, flowering period is June to August. Another blue variety for the rock garden, this time with white centred blooms is L. narbonense 'Heavenly Blue' approximately twelve inches. L. arboreum is quite different; it is a woody species with grey-green leaves and terminal clusters of large, golden-yellow flowers. Like another yellow Flax (L. flavum) it is only moderately hardy and is sometimes listed as a plant for the alpine house. The best of the yellow Flaxes is L. 'Gemmell's Hybrid' a six inch grey-green mound bearing large flowers. Site and Soil: Well-drained garden soil in full sun. Propagation: Sow seeds or plant stem cuttings in early summer.