A range of intergeneric hybrids has arisen by crossing Chamaecyparis nootkatensis with 3 different species of Cupressus, the results of the cross being plants that frequently combine favourable horticultural characteristics of the parent genera: resistance to cold and heat, fast growth, and vigour. The extraordinarily rapid growth makes this sutable as a quick-growing wind break but may exceed expectations to cause problems.
The most widely grown cross is that with Cupressus macrocarpa to produce the Leyland Cypress, ×C. leylandii. Rarely offered in the trade are ×C. notabilis Mitchell, Alice Holt Cypress (Cupressus glabra ×Chamaecyparis nootkatensis) and ×Cupressocyparis ovensii Mitchell (Cupressus lusitanica × Chamaecyparis nootkatensis).
Cultivars are propagated by cuttings.
Identification of these hybrids is difficult as the cultivars vary in their degree of similarity to either parent. However, the Leyland Cypress can generally be distinguished by common cultivars with coarse flattened foliage sprays and regular narrow-conical habit. Most cultivars when once carefully observed can generally be recognised again although precise botanical characters are difficult to define.
Ovens, Blight & Mitchell (1964), Mitchell (1970, 1979).
Source: (1995). Cupressaceae. In: . Horticultural Flora of South-eastern Australia. Volume 1, Ferns, conifers & their allies. The identification of garden and cultivated plants. University of New South Wales Press.