Cupressus guadalupensis

S. Watson 1879

Common Names

Taxonomic Notes

Syn.: Cupressus macrocarpa Gordon var. guadalupensis (S. Watson) Mast. 1895 (Farjon 2005).

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.

Little (2006) has proposed, with strong support from molecular/genetic data, that Cupressus be divided into new world and old world genera. The new world species, which are more closely related to Juniperus than to the old world species, he assigns to Callitropsis Oersted; while the old world species remain in Cupressus L. This species would then become Callitropsis guadalupensis (S. Watson) D.P. Little.

Description

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 the type variety and var. forbesii are the same color, but seeds of the type variety have a glaucous bloom and those of var. forbesii are shiny (Wolf and Wagener 1948 in Bonner [no date]). Arizona Cypress may be found with Tecate Cypress in Southern California and northern Baja California. The leaves of Arizona Cypress are sharply pointed, the points projecting outward giving the foliage a bristly appearance and feel. In contrast the needles of Tecate Cypress and rounded at the tips and more closely appressed to the branchlets (Nearctica 2000).

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]).

Range

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). The species is further and more severely limited by the grazing of goats, which have reduced its population to about 200 individuals with negligible regeneration (IUCN 2002). Although the species is also found in cultivation, it rarely produces seed outside its native island (Bonner [no date]) and the prognosis for its continued survival is poor unless the goats are removed from the island. See Instituto Nacional de Ecología (2002) for more detail on current status and conservation efforts.

Big Tree

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. I don't know if this specimen represents the type variety or var. forbesii.

Oldest

Dendrochronology

Ethnobotany

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.

Observations

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).

Remarks

This species is also listed as endangered by the Mexican government (NOM-ECOL-059-94).

Collected by Dr. E. Palmer (Watson 1879).

Citations

Bonner, F.T. (tech. ed.). [no date]. Woody plant seed manual. U.S.D.A. http://wpsm.net/Introduction.htm (2003.05.04).

Instituto Nacional de Ecología. 2002. Isla Guadalupe. http://www.ine.gob.mx/dgoece/con_eco/conhc/isla_guadalupe.html (2007.01.01).

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.