Cupressocyparis

Cupressocyparis is the name used in horticulture for an intergeneric hybrid group within the cypress family (Cupressaceae), created by crossing Cupressus (true cypress) with Chamaecyparis (false cypress). The best-known member is Cupressocyparis leylandii, commonly called the Leyland cypress, a fast-growing evergreen widely planted for screens, hedges, and windbreaks. The hybrid is generally reported as a cross between Monterey cypress (Cupressus macrocarpa) and Nootka (or Alaska) cypress (Chamaecyparis nootkatensis, also referred to as Cupressus nootkatensis).

Taxonomy and nomenclature for Cupressocyparis vary. Some authorities treat Cupressocyparis as a distinct genus, while others classify it as an intergeneric hybrid, written as X Cupressocyparis leylandii or Cupressocyparis leylandii, reflecting its hybrid origin.

Description and growth: Leyland cypress is known for a tall, pyramidal to broad crown and rapid height growth. It bears evergreen, scale-like leaves and forms dense foliage suitable for screens. In ideal conditions, it can reach substantial heights, with substantial width as well. It prefers well-drained soil and full sun, and it tolerates a range of temperate climates.

Cultivation and use: The species is widely planted in temperate regions for privacy screens, wind protection, and ornamental effect. Propagation is typically by semi-hardwood cuttings; seed from hybrids can produce variable offspring, so clonal propagation is common for landscape use.

Pests and diseases: Leyland cypress is susceptible to cypress canker diseases (Seiridium spp.) and root rots (including Phytophthora), among other issues. Disease pressure and environmental stresses have led to advisories in some regions, prompting considerations of alternative screen conifers in certain landscapes.