In its native habitat it depends on water from the fogs that envelop high ground in the northern half of the island.

It became an endangered species due to feral goats living on Guadalupe Island that – for more than a century – prevented new trees from growing.

Guadalupe cypress is a coniferous evergreen tree with a dome-shaped and broad crown when fully mature.

[3] The species is variable in size, with mature trees reaching 12–20 metres (39–66 ft) tall, though they are noted as being towards the lower end of this range in their native habitat in the 2000s.

[7] The seed cones are nearly spherical, with eight to ten horn-shaped scales, narrow at the base and wide at the top, with a pointed tip.

Inside the cone are approximately 70 to 100 seeds, brown with a light waxy coating described by botanists as glaucous.

[13] The seedlings are very similar to all other western cypress species, with three to five long, thin, needle-like seed leaves that start out upright and then spread outwards from the stem.

In the second to fourth year of life the young tree will start to produce adult foliage rather than another set of juvenile leaves.

[7] In the first year of growth, given favorable growing conditions, young trees will reach an average of 40 to 45 centimeters in height.

[14] Though Masters was followed in full or at least in part in these combinations,[15] other botanists continued to regard the species as correctly identified under the name C. guadalupensis.

[19] Though an isolated island population, Guadalupe cypress has greater genetic diversity than its mainland relatives.

[20] Further research resulted in the 2009 publication by Jim A. Bartel and others moving it and the other new world cypress trees to a new genus Hesperocyparis.

[10][24] Another, less common, name used for the species in California is "blue cypress" for the color of its foliage,[25][10] though the Australian tree Callitris columellaris is also called blue cypress by essential oil enthusiasts for the color of its extracted oil.

High winds also buffet the island during the winter, but when there were extensive groves of cypress trees the air within them was sheltered and calm.

[7] The introduction of goats to the island had an enormous effect on the population of all plant species, including Guadalupe cypress.

[20] In 1885 the botanist Edward Lee Greene observed that while there was evidence of an extensive cypress forest on the northern side of the island, only dead and fallen trees remained there.

binata), Guadalupe cypress is one of the dominant defining species of plant on the island, a keystone in its natural ecology.

Another very common bird in the groves was the endemic subspecies of the house finch, Haemorhous mexicanus amplus.

Also, with the animals destroying most vegetation, and especially the island's cloud forest, the water table dropped, further jeopardizing the remaining two main subpopulations.

[31] On 15 September 2008 a wildfire was ignited that burned for three days and spread into the Guadalupe cypress groves.

Many mature trees, damaged by years of goats chewing their bark during droughts, were completely burned by the fires.

[27] In addition to the natural regeneration, the Mexican foundation GECI has partnered with the Fondation Franklinia, a Swiss charity, to plant thousands of seedlings of the cypress and two other endangered tree species on the island since 2020.

It appears this cypress is more vulnerable to drought than other native plants on the island, such as the Guadalupe variety of Monterey Pine (Pinus radiata var.

[10] Though endangered in the wild, Guadalupe cypresses have long been cultivated in California and in other parts of the world.

[4] However, the narrow column-like (fastigiate) cultivar 'Greenlee's Blue Rocket' is reported to tolerate temperatures as low as −9.5 °C (15 °F).