Many authors have recognised that the species broadly assumes two growth habits, fastigate or horizontal, and have assigned subspecific taxonomic ranks on that basis. It is widely thought that only the horizontal form predates human activity, with the fastigate form having a horticultural origin dating to early historic or prehistoric times. Thus it is a cultivar, not a variety or subspecies. There is also some question as to whether the fastigate form is strictly heritable; it appears that "horizontal" specimens may arise from "fastigate" stock (Stankov 1999, Farjon 2005).
NZOR Concept Id
Farjon, A. 2005: A monograph of Cupressaceae and Sciadopitys. Kew, Royal Botanic Gardens.