Foliage of X. vietnamenis [Royal Botanic Gardens, Kew].

Xanthocyparis

Farjon et Hiep 2002

Common Names

Taxonomic notes

Syn.: Callitropsis Örsted 1864.

In 2001, a new conifer was discovered in Vietnam (Farjon et al. 2002). This was the first new conifer discovered since Wollemia in 1994. It was assigned, along with a species then widely known as Chamaecyparis nootkatensis, to a new genus, Xanthocyparis, with X. vietnamensis as the type species.

In 2004, Little et al. presented further studies of both these taxa, along with many species in related cupressaceous genera, and concluded that the two species do form a valid subgroup. However, Little et al. stated that C. nootkatensis had in 1865 been assigned to a monotypic genus, Callitropsis Örsted, and so that name had to be conserved, with C. nootkatensis as the type species.

Mill and Farjon (2006) then proposed that the name Xanthocyparis be conserved against Callitropsis, and the proposal was approved by the IBCN Committee on Spermatophyta in 2007. The 2006 paper is online, if you want to read a marvelously intricate piece of taxonomic reasoning. In the end, it comes down to this: no one (not even Örsted) ever actually used the name Callitropsis except when a later author (Compton 1922) mistakenly applied it to yet a different species (now called Neocallitropsis pancheri). Since its discovery, though, the name Xanthocyparis has been widely used in both the scientific literature and in the horticultural trade, and so it serves the botanical community to consign Callitropsis to the dustbin while conserving Xanthocyparis.

Little et al. (2004) performed a cladistic analysis of the Cupressoideae, a subfamily of the Cupressaceae. This subfamily was construed as including the genera Calocedrus, Chamaecyparis, Cupressus, Juniperus, Microbiota, Platycladus, Tetraclinis, and Xanthocyparis (Callitropsis). The analysis was exceptionally thorough, exploring relationships on the basis of 58 character states representing morphological and chemical features, as well as diverse genetic markers including nuclear ribosomal DNA and chloroplast DNA (matK and rbcL markers). The results established that Chamaecyparis (minus nootkatensis) is clearly monophyletic and clearly distinct from Cupressus; that Cupressus, Juniperus and Xanthocyparis (Callitropsis) form a monophyletic group; and that Cupressus appears to be paraphyletic, with the Old World taxa sister to the New World Cupressus-Juniperus-Xanthocyparis clade. That clade was specifically further examined by Little (2006), who elucidated relationships between old world and new world Cupressus in an analysis that included all species in the genus, as well as both Xanthocyparis species and quite a few other species in the Cupressaceae. He concluded that all new world Cupressus and both species in Xanthocyparis form a monophyletic clade, for which he proposed the genus Callitropsis Oersted, with C. nootkatensis as the type species. Little's (2006) proposal has not yet been widely reviewed in the taxonomic community, but is regarded with much interest.

Description

See Farjon et al. (2002) and Little et al. (2004).

Range

The two species could hardly have more disjunct ranges; C. nootkatensis in northwest North America, and C. vietnamensis in Vietnam.

Big Tree

See C. nootkatensis.

Oldest

See C. nootkatensis.

Dendrochronology

Only C. nootkatensis has received any study.

Ethnobotany

See the two species; both have a fragrant, extraordinarily decay-resistant wood that is valued extremely.

Observations

See the species descriptions.

Remarks