See the "Taxonomic notes" section of Cupressus for a discussion of the relationship between this and other, closely related Cupressus taxa in northwest Mexico and the adjacent Southwest U.S. Also see the "Taxonomic notes" for C. forbesii.
Trees 12-20 m tall and up to 50 cm dbh at maturity, usually smaller in habitat, with an irregular, spreading crown. Bark exfoliating in thin plates. Branchlets slender. Leaves scale-like, opposite in 4 rows, about 1.5-2 mm long, bright green, usually lacking a glandular dot or whitish resin. Seed cones globose, 3-3.5 cm in diameter, dull brown or gray at maturity, composed of 6-10 scales with a prominent pointed tip. Seeds about 10 to a cone, dark brown and slightly bluish pruinose (Vidakovic 1991, Nearctica 2000).
Seeds of C. guadalupensis and C. forbesii are the same color, but seeds of C. guadalupensis have a glaucous bloom and those of C. forbesii are shiny (Wolf and Wagener 1948 in Bonner [no date]).
There are about 55,000 seeds/kg, which makes them 2-7 times as heavy as seeds of other North American species of Cupressus (Bonner [no date]).
Mexico: Baja California Norte: endemic to Guadalupe Island, which it shares with one other conifer, the equally rare and endangered Pinus radiata var. binata. The island is a desert with moisture chiefly provided by fogs, which limit the species' distribution on the island (Instituto Nacional de Ecología 2002). For many years the species was further and more severely limited by the grazing of goats, which reduced its population to about 3300 individuals on about 160 ha, with negligible regeneration. However, in 2005, under the leadership of Dr. Alfonso Aguirre Muñoz, the Grupo de Ecología y Conservación de Islas, A.C. succeeded in completely eradicating the goats from this large island and the trees and vegetation are now recovering (email, Aguirre Muñoz, 2012.03.01). This is an uncommon bit of good news in the generally depressing landscape of rare conifer conservation.
The Fresno, California tree pictured here is 21 m tall and 163 cm dbh. It is probably larger than any tree in the species' native habitat.
The species has been in cultivation since about 1879 but is not frost tolerant and does not set seed outside of habitat (Bonner [no date]), thus it is rarely used as an ornamental.
The type variety can only be seen on Guadalupe Island. I do not know of any travel restrictions, but you will probably have to have or hire a boat to get there. Information on its distribution and habitat on the island are provided by Instituto Nacional de Ecología (2002).
This species is also listed as endangered by the Mexican government (NOM-ECOL-059-94).
Collected by Dr. E. Palmer (Watson 1879).
Bonner, F.T. (tech. ed.). [no date]. Woody plant seed manual. U.S.D.A. http://wpsm.net/Introduction.htm (2003.05.04).
IUCN 2002. 2002 IUCN Red List of Threatened Species. http://www.redlist.org/search/details.php?species=34080 (2007.01.01).
Nearctica. 2000. Nearctica - Native Conifers of North America - Cupressus guadalupensis. http://www.nearctica.com/trees/conifer/cupress/Cguada.htm (2007.01.01).
Watson, Serano. 1879. Contributions to American botany, 2. Descriptions of some new species of North American plants. Proceedings of the American Academy of Arts and Sciences 14: 300. http://www.cupressus.net/CUguadalupensisWatson.html, courtesy of the Cupressus Conservation Project website.
A. Aguirre-Muñoz, A. Samaniego-Herrera, L. Luna-Mendoza, A. Ortiz-Alcaraz, M. Rodríguez-Malagón, M. Félix-Lizárraga, F. Méndez-Sánchez, R. González-Gómez, F. Torres-García, J.C. Hernández-Montoya, J.M. Barredo-Barberena, and M. Latofski-Robles. 2011. Eradications of invasive mammals on islands in México: the roles of history and the collaboration between government agencies, local communities and a non-government organization. Island Invasives: Eradication and Management. Proceedings of the International Conference on Island Invasives. Gland, Switzerland: IUCN and Auckland, New Zealand: CBB. xii + 542pp. Available: issg.org.
Moran, R. 1996. The flora of Guadalupe Island, Mexico. San Francisco: California Academy of Sciences.
Last Modified 2012-11-23