Tecate cypresses with Cuyamaca Peak in the background [C.J. Earle, 7-Apr-2004].

Cones and bark on a tree at Guatay [C.J. Earle, 7-Apr-2004].

Foliage and immature cone at Guatay [C.J. Earle, 7-Apr-2004].

Mature cone from tree at Guatay [C.J. Earle, 7-Apr-2004].

Distribution of Cupressus forbesii (Griffin and Critchfield 1972).

Seedling at Guatay about 8 cm tall [C.J. Earle, 7-Apr-2004].

The big tree in Decanso (California Registry of Big Trees).

Cupressus forbesii

Jepson 1922

Common Names

Tecate or Forbes cypress (Peattie 1950).

Taxonomic Notes

Syn: C. guadalupensis S. Watson var. forbesii (Jepson) Little 1970, C. guadalupensis S. Watson subsp. forbesii (Jepson) Beauch. 1978 (Farjon 2005).

Most recent authors have treated this taxon as a variety of C. guadalupensis, but a molecular analysis by Little (2006) found that C. guadalupensis is slightly more closely related to C. stephensonii (often treated as a variety of C. arizonica). Past authors (Wolf 1948, Little 2006) have found consistent morphological, chemical, phenological, and molecular genetic differences between C. forbesii and C. guadalupensis, and they are here treated as separate species although they are difficult to distinguish using field characters in an artificial setting such as an arboretum. Also see the "Taxonomic notes" section of Cupressus for further discussion of the relationship between this and other, closely related Cupressus taxa in northwest Mexico and the adjacent Southwest U.S.

Little (2006) has proposed, with strong support from molecular/genetic data (cf. Little et al. 2004), that Cupressus be divided into new world and old world genera, with the new world species assigned to the new genus Callitropsis Oersted. This species would be called Callitropsis forbesii (Jepson) D.P. Little.

Description

Trees to 10 m tall, often shrubby; crown globose, sparse. Bark of trunks exfoliating, leaving a clear brown or rich cherry-red smooth surface, sometimes only partially peeling away, and persisting as grayish shaggy scales with curling edges. Branchlets decussate, mostly 1-1.5 mm diam. Leaves about 1.2 mm long, acute but rather blunt-tipped, rounded or ridged on the back, light rich (never glaucous) green, often with slightly darkened, inconspicuous, embedded, abaxial gland that does not produce drop of resin except on the larger leaves of vigorous young shoots. Pollen cones abundant, 3-4 × 2 mm; pollen sacs 3-5, slightly 4-sided, of 8 to 14 scales. Seed cones globose, mostly (2)2.5-3.5 cm, brown, not glaucous; scales mostly 4 - 5 pairs, smooth, umbos flat or to 5 mm, dull gray to brown. Seeds mostly 5-6 mm, plump, rich dark brown, not glaucous (Peattie 1950, Eckenwalder 1993).

Farjon (2005) notes that the pollen cones of C. guadalupensis are larger (4-7 mm, vs. no more than 5 mm for C. forbesii) and have a few more microsporophylls. Wolf (1948) finds that on C. forbesii the foliage is bright green and mature trees are not over 10 m tall, while on C. guadalupensis, foliage is more glaucous and mature trees are more than 10 m tall. Farjon (2005) dismisses these differences as "inconsistent."

Range

USA: California; Mexico: Baja California Norte. In California, occurs in the Santa Ana Mountains (Orange County); Guatay Mountain and Otay Mountain (San Diego County); and Mount Tecate on the U.S.-Mexican boundary. In Baja California Norte, found on Mt. Tecate and in El Cañon de Pinitos (110 km S of Ensenada). Habitat chaparral, at 450-1000 m. Of conservation concern (Peattie 1950, Eckenwalder 1993).

Big Tree

Pictured here, it is 21.6 m tall and 75 cm dbh, and grows in Decanso, California; measured in 2001 (California Registry of Big Trees). This is an ornamental. A smaller tree in Guatay, CA is, I believe, a wild tree. It is 14 m tall, 71 cm dbh (American Forests 2000).

Oldest

One of the largest trees I have seen had recently lost one of its two major stems in a severe winter storm. The exposed break revealed about 100 growth rings, indicating that this tree, among the largest in the stand, was not more than 120 years old. Since the species is fire-dependent and occurs in chaparral, older individuals are not likely to be found unless a tree by chance establishes on a fireproof site, e.g. on a cliff or rocky barren.

Dendrochronology

Ethnobotany

Observations

Little (1970) says that "Perhaps the most accessible grove of Tecate cypress is ... on the Cleveland National Forest, Sec. 21, T. 15 S., R. 4 E., altitude about 4,000 feet [1220 m].". To reach the site, follow Interstate 8 about 40 miles [64 km] E from San Diego and take the CA 79 exit N (towards Cuyamaca Rancho State Park, home of C. arizonica var. stephensonii) for about 4 km. Here, turn E onto Old Highway 80 and go about 3 km to reach the hamlet of Guatay, where a cafe and trailer park can be found. The stand is visible from here on the mountainside to the SW. It is most easily reached by returning down the highway about 500 m, crossing the creek in the valley bottom (forested with large oaks and Coulter pines, Pinus coulteri), and walking W along an old roadbed for not more than 5 minutes until the trees are visible directly uphill. Here a trail can be found winding up through chaparral and into the stand, which is patchy and extends nearly to the mountaintop. When I visited the site, in March 1998, I found trees up to 10 m tall and 85 cm diameter.

Remarks

Type specimen collected 1907.12.30 by Charles N. Forbes in Cedar Cañon between El Nido and Dulzura, on the N side of Otay Mt., in San Diego County, California (Jepson 1922). It was previously (1894.07.05) collected at the same locality by Edgar A. Mearns (Little 1970). Jepson (1922) named the species for "my former student, Mr. C. N. Forbes, later Assistant in Botany, Bishop Museum, Honolulu. I take pleasure in naming it in his memory."

Curiously, Pinus radiata has a similar distribution pattern. The bulk of its native range is local on the coast of central California, while a disjunct population occurs on Guadalupe Island (Little 1970).

Like some other California cypresses, this species is serotinous, the cones opening and shedding seed only after a fire or occasionally, on extremely hot days. The Tecate cypress is unusual in that many of the cones are borne directly on the trunk or major branchlets. These cones are retained and are sometimes engulfed by stem growth. This situation seems to be directly analogous to the of the closed-cone pines of California, all of which are predominantly serotinous and thus highly fire-dependent. The serotinous pines may open some cones on exceptionally hot days and perhaps that is the case in this species as well, which would explain how it can sustain regeneration despite an ongoing regime of fire suppression. The trees I saw on Guatay Mountain had a mixture of opened and closed cones.

Citations

Jepson, W.L. 1922. A new species of cypress. Madroño 1: 75. http://www.cupressus.net/CUforbesiiJepson.html, courtesy of the Cupressus Conservation Project website.