Hesperocyparis is a genus of approximately 10 species of conifer native to Western North America. Also known as the North American or western cypresses, this genus has been the subject of a large degree of taxonomic change and controversy in recent years. Formerly included in the genus Cupressus, genetic study during the early 2000's revealed that the genus was not monophyletic, meaning it was composed of multiple distinct lineages. These lineages appeared superficially similar, but had diverged long ago. On the basis of this evidence, Hesperocyparis was separated from the old world cypresses which remained in Cupressus.
To make matters worse, authorities do not agree on the number of species in this group, ranging from around 7-17. Hesperocyparis typically occur in widely spaced isolated groves, each of which has evolved in a slightly different direction from its neighbors but often without any clear dividing line that can define species. Perhaps with further research, a consensus will be found, but until then I err on the side of splitting species to preserve maximum information.
Generally, this group of trees grows quickly and are moderately to very drought resistance. They range from dull green to a silvery blue color, and can be almost columnar, spreading, or rounded in shape. Some species have smooth, colorful bark. Most are small to medium in size, but a few can grow large. In our area, they are commonly used as tough, low maintenance screens.
Several species can be seen in our area, most commonly C. arizonica and C. glabra, which are closely related and sometimes difficult to distinguish. C. macrocarpa, the Monterey cypress can also be seen occasionally, but it generally does poorly in hot climates and is very disease prone. A few others can be seen in parks and botanical gardens, including C. guadelupensis and C. abramsiana. In general, the species native to Northern California do poorly here, while those native to Southern California, Arizona, and Mexico do well. On the whole, not an exciting group of trees but a solid choice for a smaller and tough conifer if irrigation is questionable.
To make matters worse, authorities do not agree on the number of species in this group, ranging from around 7-17. Hesperocyparis typically occur in widely spaced isolated groves, each of which has evolved in a slightly different direction from its neighbors but often without any clear dividing line that can define species. Perhaps with further research, a consensus will be found, but until then I err on the side of splitting species to preserve maximum information.
Generally, this group of trees grows quickly and are moderately to very drought resistance. They range from dull green to a silvery blue color, and can be almost columnar, spreading, or rounded in shape. Some species have smooth, colorful bark. Most are small to medium in size, but a few can grow large. In our area, they are commonly used as tough, low maintenance screens.
Several species can be seen in our area, most commonly C. arizonica and C. glabra, which are closely related and sometimes difficult to distinguish. C. macrocarpa, the Monterey cypress can also be seen occasionally, but it generally does poorly in hot climates and is very disease prone. A few others can be seen in parks and botanical gardens, including C. guadelupensis and C. abramsiana. In general, the species native to Northern California do poorly here, while those native to Southern California, Arizona, and Mexico do well. On the whole, not an exciting group of trees but a solid choice for a smaller and tough conifer if irrigation is questionable.