The evergreen Ceanothus arboreus 'Trewithen Blue' originated in a notable Cornish garden and is a large and spectacular spring-flowering shrub with leaves larger than the average and great panicles of slightly fragrant, deep blue flowers. In a recess by the chimney breast, the silver wattle, Acacia dealbata, the popular florists' mimosa, is worth a trial. It would benefit from the warmth of the chimney, and needs height to show off its silvery-green, fern-like foliage and golden mimosa-like flowers. In favoured areas it can reach tree-like proportions. Slightly hardier and requiring a similar site is the all too infrequently planted New Zealand kowhai, Sophora tetraptera. The best form 'Grandiflora' displays in May and June remarkable golden-yellow flowers, pea-shaped, but somewhat tubular. Each of these flowers is at least \\ to 2in(4 to 5cm) long and they are borne in drooping racemes of four to eight flowers. This is a large shrub or even small tree with spreading branches and pinnate leaves and shoots. The flower and leaf stalks are covered when young with an unusual tawny down. The kowhai is an intriguing and beautiful plant, well worth a trial. A high south- or west-facing wall is essential for Fremontodendron (Fremon-tia) 'California Glory' (F. californica x F. mexicana). This splendid and florifer-ous hybrid seems to be hardier than either of its parents. The bright yellow flowers are at least 2in(5cm) across and are freely produced all summer. Perhaps the most distinguished and magnificent of all evergreens for growing as a wall shrub is Magnolia grandiflora. Here again a tall wall is essential and a good depth of rich, loamy soil to obtain the best from this fine shrub. 'Exmouth' is the best cultivar with 6 to ioin(i5 to 25cm) leaves, long, polished green above and rust-felted beneath. These give the plant its nobility and makes a perfect background for the immense and richly fragrant, globular flowers, creamy-white in colour and 8 to roin(20 to 25cm) across. These flowers usually appear in summer and autumn, for the first time perhaps six to ten years after planting. NORTH- OR EAST-FACING WALLS OR FENCES For a 5oft(i5m) run or I thereabouts of north- or east-facing wall or fence, early spring flowers could ยง be provided by one of the many cultivars of Chaenomeles (syn. Cydonia), the I ornamental quinces, commonly known as "Japonica". Well pruned and ? trained specimens can be most spectacular, the waxy flowers lasting over a I long period. Lateral shoots should be pruned back to two or three buds I immediately the flowers fade so that the plant will have a compact habit and I provide adequate wall coverage. A selection of the best, readily available 1 cultivars or hybrids of C. speciosa (syn. C. lagenaria) includes: 'Crimson and 1 Gold', deep red with golden anthers; 'Moerloosii', pink and white, and I reminiscent of apple blossom; 'Knaphill Scarlet', with orange-scarlet flowers 1 borne over a long season; 'Nivalis', the best, large white; 'Simonii', I semi-double blood red flowers, low growing and excellent for planting | under a window; and 'Rowallane', a large crimson flowered cultivar.