Pseudotsuga lindleyana
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Kindly sponsored by
Dansk Dendrologisk Forening, The Danish Dendrology Society
Credits
This genus has been sponsored and new text is being prepared, with publication expected in 2023.
Recommended citation
'Pseudotsuga lindleyana' from the website Trees and Shrubs Online (treesandshrubsonline.
Genus
Common Names
- Mexican Douglas-fir
Synonyms
- P. guinieri Flous
- P. macrolepis Flous
- P. menziesii var. oaxacana Debreczy & Rácz
Tree to 25–30 m (rarely to 40 m), 0.4–0.8 m dbh (rarely to 1.25 m dbh). Bark shallowly fissured, greyish brown, becoming grey and rough in older trees. Crown slender, conical, usually fairly thin and sparsely foliaged. Branchlets slender, firm, grooved, grey-brown, quickly turning grey, glabrous, leaf scars raised, circular or angular; vegetative buds not or only slightly resinous. Leaves grey-green to mid-green, 1–2(–3) × 0.1–0.12 cm, forward-pointing to spreading, often somewhat curved, with two conspicuous greyish stomatal bands on the lower surface facing outward from the shoot, upper surface facing shoot mid-green without or with only a few stomata, apex acute. Male strobili 1.5–2 cm long, yellowish. Female cones pendent, ovoid to oblong, (2–)3–6(–7.5) × 2–2.5 cm, purple to red-purple with green or yellow-green bracts, maturing pale buff-brown; peduncle with a few leaves attached, 0.5–1.5 cm long. Seed scales obovate to slightly trilobed, 1.5–2 × 1.5–2.5 cm. Bract scales linear, apex tridentate, 2.5–3 cm long, exserted, straight to outcurved or reflexed, often twisted. Seeds brown, triangular-ovoid, 0.6–0.7 cm, wings narrow-oval, pale brown, 0.7–1 cm long. Debreczy & Rácz 1995; M. Frankis, pers. comm. 2008. Distribution MEXICO: Oaxaca (south locally to 16° 22' N), Sierra Madre Occidental, Sierra Madre Oriental, Sierra Madre del Sur (rarely). The northern boundary with P. menziesii, somewhere in northern Mexico, is not yet well determined. Habitat Mixed mesophytic forest at medium to high elevations, between 2300 and 3300 m asl. USDA Hardiness Zone 8. Conservation status Not evaluated. Illustration Martínez 1953. Taxonomic note Pseudotsuga lindleyana was first described (as Tsuga lindleyana) in 1857 by Benedict Roezl, from trees found at Real del Monte near Pachuca, Hidalgo, about 90 km north-northeast of Mexico City. It has widely been dismissed as part of P. menziesii subsp. glauca (see, for example, Farjon 2001). Preliminary genetic studies (Li & Adams 1989) have suggested, however, that it is very distinct, sister to the whole of P. menziesii. For this reason, and because of its easily distinguishable appearance both in the wild and in cultivation, it is treated as a distinct species here.
Pseudotsuga lindleyana was introduced to the United Kingdom in 1963 as seed collected at c.2800 m near Tlaxco, Tlaxcala, as part of a seed exchange between the Mexican Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias and the UK Forestry Commission (Forestry Commission records; R. Jinks, pers. comms. via D. Luscombe 2007). The seed was received under the synonym P. macrolepis, and many of the resulting plants are still so-labelled. They are growing at several localities in southern England, the tallest, at Bicton Park, Devon, reaching 15 m in 2001 (Johnson 2003). The trees are not particularly decorative, having rather thin, sparse, drab green foliage (as do specimens in the wild). Their main value is in their exquisite cones, the bright yellow-green bracts setting off the purple scales very attractively; these are freely produced at eye level on young trees only 10–20 years old and 3–5 m tall.
Another seed lot from the same exchange, in this case collected near Saltillo in northern Mexico, was distributed as P. flahaultii Flous (Forestry Commission records; R. Jinks, pers. comms. via D. Luscombe 2007); this is a synonym of P. menziesii subsp. glauca (Beissn.) Schwer. These trees, planted in the same arboreta, differ conspicuously from P. lindleyana in their denser foliage with somewhat longer, strongly glaucous blue-green leaves, as expected of P. menziesii subsp. glauca. The frequent inclusion of P. lindleyana in P. menziesii var. glauca is likely to mean that there are incorrectly identified specimens in arboreta, and material of known Mexican origin should be checked, but Frankis 149, from 3000 m asl on the moist east flank of Cerro Potosí in Nuevo León, matches P. lindleyana in its sparse foliage with short, dull green needles.