(C.B. Wolf) Bartel
G1Critically ImperiledGlobal Rank
Critically endangeredIUCN
Very high - highThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.135758
Element CodePGCUP04013
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
IUCNCritically endangered
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumConiferophyta
ClassPinopsida
OrderPinales
FamilyCupressaceae
GenusHesperocyparis
SynonymsCallitropsis stephensonii(C.B. Wolf) D.P. LittleCupressus arizonica ssp. stephensonii(C.B. Wolf) BeauchampCupressus arizonica var. stephensonii(C.B. Wolf) LittleCupressus stephensoniiC.B. Wolf
Other Common NamesCuyamaca cypress (EN)
Concept ReferenceKartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.
Taxonomic CommentsHesperocyparis stephensonii (syn. Cupressus stephensonii) is considered a genetically distinct species of the Cuyamaca Mountains of California by Little (2006), Adams et al. (2009), and Baldwin et al. (2012). Other floras have treated this entity in various ways: as a subspecies of Cupressus arizonica by Kartesz (1999), submerged into C. arizonica var. arizonica by Bartel (in Hickman 1993), or as a synonym of C. arizonica in the Flora of North America (1993a, vol. 2). Little (2006) transferred all Western Hemisphere Cupressus to the genus Callitropsis and Adams et al. (2009) further isolated the Western Hemisphere cypress lineage into a new genus Hesperocyparis. Little (2006) and Adams et al. (2009) recognize the following species: Callitropsis arizonica, Callitropsis glabra, Callitropsis nevadensis (syn. Cupressus arizonica ssp. nevadensis), and Callitropsis stephensonii (syn. Cupressus arizonica ssp. stephensonii), which Flora of North America (1993, vol. 2) include in synonymy.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2021-11-02
Change Date1999-07-21
Edition Date2021-11-02
Edition AuthorsMaybury, K. (1997), rev. Treher (2021)
Threat ImpactVery high - high
Range Extent250-1000 square km (about 100-400 square miles)
Number of Occurrences1 - 20
Rank ReasonsCupressus arizonica ssp. stephensonii occurs in the mountains of San Diego County, California in the United States and in the Sierra Juarez Mountains of nearby northern Baja California, Mexico. Infrequent wildfires are important for the regeneration of stands, as the cones need fire to release their seeds. Wildfires that occur too frequently kill the young trees before they can reach reproductive maturity. Too frequent fires have led to significant population declines. The status of the species in Mexico is unknown. Continuous monitoring is needed to monitor the impact of ongoing and emerging threats, and population size and trends. Fire management geared to the age of stands may be needed to protect the species.
Range Extent CommentsThis taxon is endemic to California in the western United States and Baja California in western Mexico. It is found in the vicinity of Cuyamaca State Park and Mount Laguna in San Diego County, California, and in the Sierra Juarez Mountains of northwestern Baja California, Mexico (Moran 1977 as cited in USFWS 1995).
Occurrences CommentsThere are five locations in California and one in Mexico.
Threat Impact CommentsThis taxon is threatened by an increase in fire frequency. While the cones are serotinous and need fire to open, too-frequent fires kill the trees before they reach reproductive maturity. Another possible threat is an infestation of fire-damaged trees by the cypress bark beetle (Phloesinus spp.) (USFWS 1995, Skinner and Pavlik 1994).