'Blue Giant') has larger, freely produced flowers up to 2in(5cm) long with conspicuous white centres. C. armandii is the best evergreen species, and this is generally available in two cultivars, 'Snowdrift', with clusters of pure white flowers, and 'Apple Blossom', white, shaded pink. These flower in April and early May. The long, leathery leaves provide an effective and unusual year-round wall coverage. C. chrysocoma is, in effect, a refined, less rampant C. montana wiffl soft pink flowers produced in May and June. Ideal for a pergola upright is C.xdurandii (C. integrifoliaxC. X jackmanii), an unusual semi-herbaceous hybrid with spectacular violet-blue flowers measuring 4in(iocm) across. These are produced all summer. Equally desirable and slightly more robust is C. macropetala. This is like a double-flowered, violet-blue C. alpina; its shell-pink cultivar, 'Markham's Pink', (syn. 'Markhamii') is especially lovely. Popular, vigorous and beautiful C. montana and several of its cultivars are very well known and perhaps some are rather over-planted. They will succeed in most aspects and are particularly useful for covering trees and outhouses. Among the most notable cultivars are 'Alexander' with large well-scented, creamy-white flowers; 'Grandiflora', perhaps the best white-flowered form for general planting; var. rubens, the popular rose-pink form with red-purple shoots and leaves; and the newer Teh-arose', which is less rampant and very striking with its lilac-pink flowers up to 3! intern) across. Clematis tangutica is undoubtedly the best yellow-flowered species and an indispensable plant for every garden. It is excellent for clambering over low walls, hedges or tripods, the distinct bell-shaped yellow flowers appearing in late summer and autumn and mingling effectively in the later stages with the silky seed heads. C. viticella, the true virgin's bower, is a useful and effective, moderately vigorous species for pergola or tripod, best represented by its cultivars or hybrids, notably 'Alba Luxurians', white, tinted mauve, 'Kermesina', crimson, and 'Royal Velours', deep purple. The large-flowered garden clematis are frequently planted with climbing roses, ceanothus, garrya or other wall shrubs which are out of flower in the summer months. Be careful, however, not to plant in close competition with the roots of the host plant. Some shade is desirable for pale pink cultivars, such as 'Nelly Moser', which tend to fade quickly in hot sunlight. There is a troublesome fungal disease, clematis wilt, which can be very distressing when it occurs as it causes the sudden overnight collapse of apparently healthy plants, often full of bud and flower. If this occurs, affected shoots (if need be the whole top of the plant) should be removed; cut back to below soil level if necessary until live healthy tissue is encountered. Even small wounds should be sealed with Arbrex or a similar fungicidal tree paint, and any remaining top shoots-and new shoots as they occur-should be sprayed, at about fortnightly intervals, with Bordeaux mixture or a liquid copper fungicide.