Hesperocyparis
Credits
New article for Trees and Shrubs Online.
Recommended citation
'Hesperocyparis' from the website Trees and Shrubs Online (treesandshrubsonline.
Family
- Cupressaceae
Species in genus
- Hesperocyparis arizonica
- Hesperocyparis bakeri
- Hesperocyparis benthamii
- Hesperocyparis forbesii
- Hesperocyparis glabra
- Hesperocyparis goveniana
- Hesperocyparis guadalupensis
- Hesperocyparis lusitanica
- Hesperocyparis macnabiana
- Hesperocyparis macrocarpa
- Hesperocyparis pygmaea
- Hesperocyparis sargentii
- Hesperocyparis stephensonii
Editorial Note
In recent years the relationships between the true cypresses of the northern hemisphere (Cupressus sensu lato) and the Nootka and Vietnamese Cypresses have been intensively studied and hotly debated. The best interpretation of the various results is that the true cypresses should be split along New World / Old World lines. As the genus Cupressus was founded on C. sempervirens, an Old World species, a new genus, Hesperocyparis Bartel & R.A.Price, was published in 2009 to accommodate the New World species. In recent years this approach has become the generally accepted view, so we are therefore implementing these nomenclatural changes on Trees and Shrubs Online in October 2024: the text in the species articles will remain unchanged from the accounts in Trees and Shrubs Hardy in the British Isles and New Trees until such time as we receive sponsorship to update them, but they will now appear under the correct modern name with appropriate synonymy. If you would like to support the revision of these articles please contact the editors.
TC, October 2024.
Hesperocyparis Bartel & R.A.Price was described in 2009 to accommodate the true cypresses distributed in the western hemisphere, formerly included in Cupressus. Little (2006) had already demonstrated via molecular analysis that there was sufficient evidence to split Cupressus along approximately Old World / New World lines, and he made combinations for New World Cupressus in the genus Callitropsis Oerst., first published in 1824 for the the Nootka Cypress. Little also included the 1999 discovery Vietnamese Yellow Cypress within his concept of Callitropsis.
Unfortunately, the name Callitropsis had been the subject of considerable confusion; this was only resolved in 2009 when Debreczy et al. (2009) demonstrated that Little’s 2006 use of Callitropsis for the North American true cypresses was invalid because, according to the rules of botanical nomenclature, this name must be applied to the Nootka Cypress, the type species, and further phylogenetic work had already demonstrated that this does not nest within the North American true cypresses, but is a sister to that group; the Vietnamese Yellow Cypress is, effectively, a cousin to those two sisters (Yang et al. 2022). Adams, Bartel & Price (2009) therefore described a new genus, Hesperocyparis, with the familiar Monterey Cypress as the type species, to accommodate the North American true cypresses, making the necessary combinations available. The Nootka Cypress, after being regarded as an ill-fitting member of the genus Chamaecyparis for most of the 20th century, was restored to Callitropsis which remains a monospecific genus, as does Xanthocyparis, whose sole species is the Vietnamese Yellow Cypress. For a more in depth overview of the various twists and turns affecting this part of the Cupressaceae, see the genus account for Callitropsis.
This ‘four genus’ approach – Cupressus (Old World taxa); Hesperocyparis (New World taxa formerly included in Cupressus); Callitropsis (Nootka Cypress) and Xanthocyparis (Vietnamese Yellow Cypress) – has become the broadly accepted taxonomy for this group of Cupressaceae. It is now followed, for example, by resources including Plants of the World Online, World Flora Online, and by several major collections.
