Picea engelmannii subsp. mexicana

(Martínez) P. Schmidt 1988

Common names

Mexican spruce.

Taxonomic notes

Syn: P. mexicana Martínez (1961); P. engelmannii var. mexicana (Martínez) Taylor & Patterson (1980) nom. inval. (basionym not fully cited); P. engelmannii var. mexicana (Martínez) Silba (1984).

Although often cited as a variety (Taylor and Patterson 1980, Taylor et al. 1994), the substantial difference in climatic adaptation (USDA zone 7, vs. 3-4 in the type), and chemical similarities to P. sitchensis (Taylor et al. 1994) justify the treatment at subspecies rank proposed by Schmidt (1988).

Description

"This ssp. differs from the typical ssp. in its lighter (grey) bark, its narrower leaves (1-1.2 mm) and its narrower and slightly longer bract scales (4-6 mm)" (Farjon 1990). The bract scale measurement is not wholly reliable, as equally long bracts can be found on the typical subspecies, but the cones can be distinguished by their larger mean size (4.5-8 cm, vs. 3-6cm in the type) and slightly larger seed scales, but there is much overlap (cones in collection of M. P. Frankis); see also Taylor et al. (1994).

Range

Mexico: First found in the Sierra de la Marta, 75 km SE of Saltillo in Nuevo Leon, NE Mexico. It grows on steep, moist, north-facing slopes on soils derived from dolomite, at 3000-3400 m elevation (Farjon 1990). Another population on Cerro Mohinora in S Chihuahua, discussed as uncertain by Taylor and Patterson (1980), has now been assigned to ssp. mexicana (Farjon 1990, Taylor et al. 1994). USA: The population of Picea engelmannii in the Chiricahua Mts of Arizona is now referred to this subspecies (Taylor and Patterson 1980: p.438); those in the Sierra Blanca, New Mexico (material in collection of M P Frankis) probably also belong here. USDA hardiness zone 7.

This species (under the name Picea mexicana) is listed as endangered in Mexico under NOM-ECOL-059-94.

Big tree

Oldest

Dendrochronology

Ethnobotany

Observations

Remarks

Citations

Taylor, R. J. & T. F. Patterson. 1980. Biosystematics of Mexican spruce species and populations. Taxon 29 (4): 421-469.

This page co-edited with Michael P. Frankis, 1998.12.

See also