  Needles and twigs of a 1.3 m tall sapling in the Seattle arboretum. Image width 10 cm [C.J. Earle].
| Picea engelmannii ssp. mexicana (Martínez) P. Schmidt 1988Common NamesMexican spruce.Taxonomic notesSyn: 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).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)" (1). 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 (3).RangeMexico: 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 (1). Another population on Cerro Mohinora in S Chihuahua, discussed as uncertain by Taylor and Patterson (2), has now been assigned to ssp. mexicana (1, 3). USA: The population of Picea engelmannii in the Chiricahua Mts of Arizona is now referred to this subspecies (2: p.438); those in the Sierra Blanca, New Mexico (material in collection of M P Frankis) probably also belong here. USDA hardiness zone 7.Big TreeOldestDendrochronologyEthnobotanyObservationsRemarksAlthough often cited as a variety (2, 3), the substantial difference in climatic adaptation (USDA zone 7, vs. 3-4 in the type), and chemical similarities to P. sitchensis (3) justify the treatment at subspecies rank proposed by Schmidt (1988).Citations(1) Farjon 1990.(2) Taylor, R. J. & T. F. Patterson. 1980. Biosystematics of Mexican spruce species and populations. Taxon 29 (4): 421-469 (3) Taylor, R. J., T. F. Patterson & R. J. Harrod. 1994. Systematics of Mexican Spruce - Revisited. Systematic Botany 19: 47-59. This page co-edited with Michael P. Frankis, Dec-1998. |
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