Pseudotsuga menziesii (Mirb.) Franco

The very distinctive cones of Pseudotsuga menziesii with their conspicuously exserted bracts. Yorkshire Arboretum, March 2020. Image John Grimshaw.

W.J. Bean advised his readers to visit Perthshire 'to see this tree in its finest condition'. His advice continues to be borne out by examples such as these, planted on the Winding Terrace at Murthly Castle in the 1840s. Image Tom Christian.

Pseudotsuga menziesii approaching 60 m in the sheltered environment of Glen Massan at Benmore Botanic Garden, Argyll, UK. April 2022. Image Tom Christian.

The deeply fissured and furrowed bark in the bole of old Pseudotsuga menziesii is another distinctive character of this tree. This particularly fine example grows in the policies at Murthly Castle, Perthshire, UK. May 2021. Image Tom Christian.

An unusual example of a multi-stemmed Pseudotsuga menziesii, one of several enormous examples of this species that punctuate the landscape of Dawyck Botanic Garden in the Scottish Borders. July 2020. Image Tom Christian.

This Pseudotsuga menzeisii near Dunster, Somerset, UK, was planted in 1874 and was 61.2 m tall in 2017, at the time the second tallest example in England. 22 July 2023. Image Tom Christian.

The lower trunk of one of England's biggest Pseudotsuga menziesii at Monk Coniston, Cumbria. Though dwarfing the surrounding native vegetation, trees like this one are still potentially in their infancy. Image Owen Johnson.

An upright, nearly fastigiate Douglas Fir on the Cortachy Castle estate, Angus, Scotland. Image Owen Johnson.

This Pseudotsuga menziesii in Eggesford Forest in mid-Devon, grown from David Douglas' original seed consignment, has the distinction of being the exotic tree with the longest unbroken reign as national champion (for girth) in the UK: 154 years as of 2022. Its massive low limbs testify to a difficult early life, but it is now thriving within the shelter of taller Douglas Firs planted a century later by the Forestry Commission. May 2013. Image Owen Johnson.

Pseudotsuga menziesii is a very adaptable tree – it's seen here thriving at Villa Reale di Marlia, near Lucca, Tuscany (September 2023). Image John Grimshaw.

Pseudotsuga menziesii pollen cone and terminal bud. Dawyck Botanic Garden, UK, April 2022. Image Tom Christian.

This lead label at Althorp Park in Northamptonshire, probably dating like the tree itself from 1851, is a reminder of how the botanical names even of the most familiar trees are prone to revision. Image Owen Johnson.

Pseudotsuga menziesii to 58.5 m tall in the shelter of Glen Massan, Benmore Botanic Garden, Argyll; May 2017. Image Owen Johnson.

Western North American conifers, with Pseudotsuga menziesii pre-eminent among them, have begun to dominate many landscapes in the Scottish Highlands, to whose conditions these trees are almost perfectly adapted. A wood of Douglas Firs to 60 m tall in May 2017 below the Pass of Killiecrankie in Perthshire, not very far from the birthplace of David Douglas who first introduced this tree and from whom it gets its common name. Image Owen Johnson.

Pseudotsuga menziesii dominating the forest in the Siskiyou Mountains, Oregon (March 2010). Image John Grimshaw.

Pseudotsuga menziesii (Siskiyou Mountains, Oregon, March 2010). Image John Grimshaw.

Pseudotsuga menziesii dominates many designed landscapes in northern Britain, perhaps none more so than Murthly Castle in Perthshire, where extensive avenues and winding terraces were planted with Douglas Fir in the 1840s. June 2020. Image Tom Christian.

Foliage on Pseudotsuga menziesii, a wild collection from Washington, growing at the Sir Harold Hillier Gardens, UK (13 April 2015). Image © Jan De Langhe - Arboretum Wespelaar.

Dark green needle upper surface with grooved midvein on Pseudotsuga menziesii (Sir Harold Hillier Gardens, UK – 13 April 2015). Image © Jan De Langhe - Arboretum Wespelaar.

Conical bud and whitish-green stomata-bands on needles below of Pseudotsuga menziesii (Sir Harold Hillier Gardens, UK – 13 April 2015). Image © Jan De Langhe - Arboretum Wespelaar.

Minutely pubescent branchlets on Pseudotsuga menziesii (Sir Harold Hillier Gardens, UK – 13 April 2015). Image © Jan De Langhe - Arboretum Wespelaar.

Seed cones on Pseudotsuga menziesii (Sir Harold Hillier Gardens, UK – 13 April 2015). Image © Jan De Langhe - Arboretum Wespelaar.

Seeds on Pseudotsuga menziesii (Sir Harold Hillier Gardens, UK – 13 April 2015). Image © Jan De Langhe - Arboretum Wespelaar.

'Agija'

A leaderless, slow growing pyramidal plant with thin, contorted branches and pale green foliage. In ten years 1.5 × 1 m. Raised as a seedling in 2001 by the late Aris Auders, Latvia, and named after his wife (Auders & Spicer 2012).

'Alber's Elegant Weeping'

A narrow, graceful, weeping plant raised by Sam Pratt, Washington, and named for his mentor Dr John Elbers (Hatch 2021–2022).

'Albospica'

Young foliage nearly pure white, greening up after several weeks. Raised from seed before 1920 by C. van Geert, Kalmthout Arboretum, Belgium, but probably not now in cultivation (Auders & Spicer 2012).

'Anguina'

A sparsely branched plant with ‘only a few chaotically twisted, secondary snake-like branches’ (Auders & Spicer 2012). At up to 5 cm long the typical green needles are longer than the typical maximum for the species. ‘Anguina’ was raised prior to 1923 in Endsleigh, Devon, UK but has probably been lost to cultivation (Hatch 2021–2022).

'Appressa'

An unusual selection with the pale glaucous-green leaves adpressed to the new shoots (Hatch 2021–2022) a trait sometimes observed in plants of var. glauca. Raised by von Schwerin in 1901 but probably lost to cultivation (Auders & Spicer 2012).

'Argentea'

Described as ‘An upright plant with silvery blue-white needles’ (Auders & Spicer 2012). Raised c. 1875 by M. Koster & Sons, Netherlands, but probably lost to cultivation.

'Astro Blue'

A dense, broadly pyramidal tree with intense, pale glaucous leaves. It was raised by the Vermeulen Nursery of New Jersey in 1968 who originally named it ‘Compacta Glauca’ (Hatch 2021–2022). This name was invalid in Latin form as it was published after 1959, besides which the name ‘Compacta Glauca’ had already been used before 1902 by the Ansorge Nurseries, Germany for a different clone (see under Dwarf Cultivars) (Auders & Spicer 2012).

'Aurea'

A plant with pale yellowish new growth, becoming whitish later, raised from seed by A. Sénéclauze, France, c. 1862; ‘Later authorities including Beissner (1909), von Schwerin (1922) and Krüssmann (1960) referred [this name] to a different plant originating from Cultoquhey near Crieff, Scotland, described as having the young growth sometimes a clear primrose-yellow in July’ (Auders & Spicer 2012).

'Aureo Marginata'

An upright but otherwise lax tree, to 3 × 2 m in ten years. The green leaves have white margins, the effect best when it is grown in some shade. Introduced to commerce by Stanley & Sons Nursery of Oregon, in 2005, but the cultivar name in Latin form is invalid unless published before 1959 (Auders & Spicer 2012).

'Big Flats'

A vigorous tree with pendent branches and long glaucous needles. Selected in 1955 by Dick Fennechie from the New York State Nursery in Big Flats, New York (Auders & Spicer 2012). It was still in American commerce in the late 1990s (Jacobson 1996).

'Blue'

A tree with a habit like that of the species but clear blue foliage. Received by Iseli Nursery from Bush Nursery, Oregon before 1985 (Auders & Spicer 2012).

'Blue Wonder'

A medium-sized tree of conical habit with strongly glaucous foliage – ‘among the brightest and best blues’ for American authority Larry Hatch – the leaves 3–3.5 cm long and in ten years plants are 2–3 × 1.5 m. The name is problematic. First raised from seed by P. Lombarts in the Netherlands in 1910, it was listed in the 1936 Lombarts catalogue as ‘Lombartsii Glauca’ and then in 1958 as ‘Blue Wonder’, but in the intervening period it was listed simply as ‘Lombarts’ in the 1938 catalogue and as ‘Lombarts’ and ‘Blue Wonder’ by den Ouden in 1940 (Hatch 2021–2022; Auders & Spicer 2012). Perhaps the nursery finally settled on ‘Blue Wonder’ to clear up some of this confusion.

'Boulder Blue'

A slow-growing upright plant with leaves a good pale blue. To 1.5 × 1 m in ten years. Known in American cultivation since before 2000 (Auders & Spicer 2012).

'Brevibracteata'

This name was originally used as a botanical variety, described in 1841 covering plants occasionally found in the wild with very short bracts on the female cones. As a cultivar, the name (probably invalidly) applies to a plant listed by Herm. A. Hesse Nurseries in 1962 (Auders & Spicer 2012).

'Brevifolia'

A rather slow-growing, small tree with stiff, radially arranged pale green leaves, 0.6–1.3 cm long, very densely set on the shoot with an occasional leaf pointing backwards. Raised from seed at the Elvaston Nurseries, near Derby, UK, before 1875 (Auders & Spicer 2012; Bean 1976).

'Caesia'

This name was first applied as a botanical variety by von Schwerin in 1907, to cover glaucous plants in the wild in British Columbia. Some authors consider var. caesia to represent trees intermediate between var. menziesii and var. glauca, but the described variation falls within the concept of var. glauca adopted here (see taxonomic note in that article). The name was later used as a cultivar for a single clone (Auders & Spicer 2012).

'Caesia Erecta'

Like plants once labelled var. caesia (see ‘Caesia’ above) ‘Caesia Erecta’ has somewhat glaucous grey-green leaves, often pectinately arranged on glabrous to subglabrous shoots, but a more erect branching structure (Hatch 2021–2022). It was first recorded by von Schwerin c. 1922 but is probably not now in cultivation (Auders & Spicer 2012).

'Candida'

A form with the young foliage silvery white, turning green in its first winter and darker again in the second. It was found in Waterford, Ireland, and recorded in the third edition of Dallimore & Jackson’s Handbook of Coniferae and Ginkgoaceae (1948) and subsequently (Dallimore & Jackson 1966) but has probably been lost to cultivation (Auders & Spicer 2012).

'Cascade'

A vigorous weeping tree with green foliage raised by Mark Weiss and put into commerce by Stanley & Sons Nursery, Oregon, USA in 2006 (Hatch 2021–2022; Auders & Spicer 2012).

'Cedar Ridge Curly Weeper'

A wide-spreading, weeping plant with oddly twisted and curled branches and dark green foliage (Auders & Spicer 2012).

'Coenosium Gold'

A moderately slow-growing plant of upright habit with golden-yellow foliage, to 2 × 1 m in ten years. Raised before before 1999 in the eponymous Coenosium Gardens, Washington, USA (Auders & Spicer 2012).

'Coeur d'Alene'

Selected in or near the eponymous city in Idaho c. 1990, this selection of var. glauca has grey needles and forms a dense, pyramidal, very hardy tree (Jacobson 1996).

'Crispa'

A tree with sickle-shaped leaves, somewhat bluish on the young growth, raised from cultivated seed of var. caesia (see ‘Caesia’) before 1919 by von Schwerin but probably now lost to cultivation (Auders & Spicer 2012).

'Cross Selection'

A slow-growing selection with short greyish-blue leaves, to 2 × 1 m in ten years. Raised by Jim Cross of Environmentals Nursery, New York, and in commerce by 2009 (Auders & Spicer 2012; Hatch 2021–2022).

DEEP MOUNTAIN^®

The registered trademark (without a cultivar name) for seed-raised plants of densely pyramidal habit, deep green leaves and late bud-break, improving frost resistance in cold climates. Young plants can grow up to 30 cm per year. Listed by Carino Nurseries, Indiana, Pennsylvania in 2004 (Hatch 2021–2022).

'Delbert's Weeping'

A selection listed by Iseli Nursery, Oregon, in 1983, described as having gracefully arching branches and very dark green leaves by Auders & Spicer (2012).

'El Dorado'

A relatively recent introduction found by Richard Haslebacher and Lalo Villarreal of Woods Creek Horticultural in Oregon. ‘El Dorado’ is typical of the species but with the young growth rich golden-yellow; the parent plant apparently produces yellow seedlings (Hatch 2021–2022; coniferkingdom.com 2023).

'Elegans'

A small, irregularly but densely branched tree with pendulous, horizontal and ascending branches and rather short grey-glaucous leaves. To 3 × 2 m in ten years. Recorded by Beissner in 1887 (Auders & Spicer 2012).

'Faber'

A selection with the youngest shoots bearing golden-yellow leaves (cf. ‘El Dorado’, above). Raised in 1916 by H.H. Faber, Illinois (Auders & Spicer 2012).

'Fletcheri'

A shrubby selection of var. glauca (Bean 1976) forming a broad, flat-topped or globose bush with somewhat radially arranged grey-green leaves. It is potentially of moderate growth when young and may reach 1 × 1.5 m within ten years but soon slows right down, and after many decades old plants may only measure 1–3 m tall, but will almost always be wider than tall. It was one of two similar seedlings raised at the Lock King Nursery, UK and introduced by Fletcher Brothers in or before 1915; the bluer selection was named ‘Nana’, but it never seems to have enjoyed the popularity of ‘Fletcheri’, which for the American authority Larry Hatch remains one of the best of the dwarf selections (Auders & Spicer 2012; Hatch 2021–2022).

Pseudotsuga menziesii 'Fletcheri' in the Heather Garden, part of the Valley Gardens, Windsor Great Park, UK. 17 May 2009. Image Derek Spicer.

'Fort Lewis'

A narrow plant with green foliage of good vigour, with annual growth up to 30 cm. Origin and ultimate size not recorded (Hatch 2021–2022; Auders & Spicer 2012).

'Fournier's Greenspire'

A slow-growing plant with a compact pyramidal to columnar habit and somewhat contorted stems; to 2 × 1 m in ten years (Auders & Spicer 2012). A ‘perfect Christmas tree’ says Hatch (2021–2022). In US commerce since 2002.

'Fraser River'

A name listed by George Jackman & Son, UK, in 1934 for a selection of var. glauca from somewhere on the Fraser River in British Columbia (Auders & Spicer 2012). The name perhaps represented nothing more than the provenance.

'Fretsii'

A small to medium sized, slow-growing tree, broadly conical in outline and often relatively sparsely branched, with short, radially arranged dark green leaves. Raised before 1905 by G. Frets & Son, the Netherlands (Auders & Spicer 2012). In the UK there are examples to 22 m × 71 cm dbh (2019) at RHS Garden Wisley, Surrey, and 20 m × 76 cm (2017) at Pitcarmick, Perthshire (Tree Register 2023) but it is rarely propagated or planted now.

Pseudotsuga menziesii 'Fretsii' is a slow-growing form with short leaves. RHS Garden Wisley, UK, 2 September 2022. Image Tom Christian.

The UK and Ireland champion Pseudotsuga menziesii 'Fretsii' at RHS Garden Wisley, 22 m in 2019. Image Tom Christian.

Pseudotsuga menziesii 'Fretsii', sometimes slow-growing, has reached 20 m at Pitcarmick, Perthshire, UK. June 2017. Image Owen Johnson.

'Glauca Fastigiata'

A narrowly pyramidal tree (at least in youth) with rich glaucous foliage raised in 1913 in Rochester, New York. It is distinct from the ‘Fastigiata’ raised in Britain (see above) (Hatch 2021–2022).

'Glauca Pendula'

A selection of var. glauca with more or less horizontal branches and pendent branchlets raised before 1891 from American seed by Simon-Louis Frères, France (Hatch 2021–2022). It can be quite vigorous; in 2002 a plant at the Sir Harold Hillier Gardens, UK, had reached 7.7 m × 15 cm dbh after c. 25 years while another at Bute Park, Cardiff, was 5 m after 15 years in 2005 (Tree Register 2023).

'Glenmore Blue'

Selected by R.E. More in 1948 from a wild tree in Jefferson County, Colorado, for the good vivid blue colour of its leaves (Auders & Spicer 2012).

'Gotelli's Weeping'

A naturally leaderless shrubby plant with grey-green leaves which forms a spreading mat unless staked. Relatively vigorous, with annual growth to 30 cm. Raised in the United States prior to 1980 (Auders & Spicer 2012).

'Graceful Grace'

An elegant, narrow, weeping tree that does not require staking; the unusually long leaves are a good glaucous green (Auders & Spicer 2012; Jacobson 1996). There is some confusion as to its origin, with Auders & Spicer (2012) and Hatch (2021–2022) giving quite different accounts. Potentially quite vigorous under the right conditions – Auders & Spicer (2012) suggest 2–3 × 1–2 m after ten years – an example at the Sir Harold Hillier Gardens is much slower, in 2007 it was 2.4 m tall after 23 years (Tree Register 2023).

Beware of confusion with ‘Grace’ (see under dwarf cultivars).

'Hayfork Gold'

A semi-dwarf selection of conical habit and slow growth, raised by Bill Wilson and put into commerce by 2006 (Auders & Spicer 2012).

'Helms'

A slow-growing plant of upright habit with pale green leaves. Annual growth 10–15 cm (Auders & Spicer 2012).

'Hess Blue'

Introduced by the Hess Nurseries of Cedarville, New Jersey (nothing to do with the Hesse Nursery of Germany) in 1977, for Jacobson and Hatch this is one of the best of the glaucous selections, with bright, waxy, bright blue leaves (Hatch 2021–2022; Jacobson 1996). Of moderate vigour, to 2 × 1 m in ten years (Auders & Spicer 2012).

'Hillside Gold'

Raised at Hillside Gardens, Pennsylvania, c. 1970. Jacobson described this as ‘a tree with a golden cast’ and ‘extremely rare’ (Jacobson 1996). Auders & Spicer describe what sounds like a rather different plant under this name: ‘A slow-growing pyramidal plant with blue-green (chartreuse) foliage turning green then yellow in winter. In ten years 3 × 1.5 m. Received by Iseli Nursery, OR, USA from Hillside Gardens, PA, USA in 1981’ (Auders & Spicer 2012) whilst Hatch (2021–2022) says ‘gold suffused or tinged’.

'Idaho Weeper'

A variable selection of var. glauca (albeit with not particularly glaucous foliage) with a contorted leader and somewhat pendulous branches, tending to grow broader than tall unless staked when young. Annual growth 30–50 cm. Found in Idaho by Warren Carnefix then named in Oregon 1989, it was in commerce by 1992 (Auders & Spicer 2012; Jacobson 1996). There is some uncertainty around the correct name; Hatch (2021–2022) uses ‘Carnefix Weeping’ while Jacobson (1996) and Auders & Spicer (2012) prefer ‘Idaho Weeping’ and ‘Idaho Weeper’ respectively. Hatch names this among his top selections of Pseudotsuga menziesii.

'Kooteney Lake'

A pendant, sparsely branched plant with dark green leaves, found as a budsport Kooteney Lake, in the Rockies of southern British Columbia, Canada. Appeared in the 1983 catalogue of Horstmann Nurseries, Germany (Auders & Spicer 2012).

'Leenderheide'

Similar to the more widely grown ‘Serpentine’ (see below) this forms a moderately vigorous plant of upright habit with variably curled and twisted stems and green leaves. To 3 m in ten years. Raised in the Netherlands prior to 2005 (Auders & Spicer 2012).

'Lombartsii Pendula'

A slow growing plant, after many years a tall tree with pendulous branches and pale green needles to 2.5 cm long. Raised from seed in 1910 by P. Lombarts, the Netherlands (Hatch 2021–2022; Auders & Spicer 2012).

'Longifolia'

Recorded by Cooper in the proceedings of the 1931 RHS Conifer Conference (Chittenden 1932) and noted as being a vigorous tree with particularly long needles (to 37 mm), in modern terms this would be regarded as falling comfortably within the variation of the species and the name becomes superfluous.

'Marshall'

A slow-growing, densely branched, conical selection of var. glauca, raised c. 1930 in Colorado and introduced by the Marshall Nursery, Nebraska. A plant at the Morton Arboretum was 2.3 m after 14 years (Jacobson 1996).

'Metolius Weeper'

Discovered before 2013 along the Metolius River in Oregon by Art Anderson and Tim Moriarty, and apparently also by Frank Hoffman in the same year. The original tree was a tall, sturdy plant with a narrow crown and pendulous branches but has since been killed by fire (Hatch 2021–2022).

'Moerheimii'

An altogether rather irregular plant, generally of compact, upright growth with a proportion each of straight and curved or bowed branches and of irregularly sickle-shaped glaucous green leaves to 4 cm long. Raised by B. Ruys, Royal Moerheim Nursery, the Netherlands in 1912 (Hatch 2021–2022; Auders & Spicer 2012). Two trees at the Sir Harold Hillier Gardens, Hampshire, UK were 19.2 m × 35 cm dbh and 10 m × 24 cm dbh in 2017, but their ages are unknown (Tree Register 2023).

'Mossman'

A name of uncertain application, listed by Suncrest Gardens, PA, USA in 1993 without a description (Auders & Spicer 2012). The same material is possibly in circulation under the following additional names:

• ‘Mossman Pendula’ Listed by Peace of Mind Nursery Inc., OR, USA in 2009
• ‘Mossman Weeping’ Listed by Yellowood Nursery, USA in 2009

'Mount Hood Weeper'

A vigorous weeping plant found on Mt Hood, Oregon (Hatch 2021–2022).

'Nana'

Despite the name, this clone does not qualify as a ‘dwarf cultivar’ as defined here, that is to say remaining less than 1 × 1 m in ten years. Those very slow-growing forms, mostly derived from nearly identical witches’ brooms, are treated under the heading ‘Dwarf Cultivars’. In contrast to most of those, ‘Nana’ is a comparatively vigorous plant of strong growth, conical habit, with stiff, somewhat glaucous-green leaves arranged radially around the shoots (Auders & Spicer 2012). It is similar to and of the same origin as ‘Fletcheri’, having been raised before 1895 in Lock King Nursery, UK, and introduced to the trade by Fletcher Brothers, who originally sold these plants under the name ‘Fletcheri’ until Hornibrook renamed the second clone ‘Nana’, distinguished by its longer, bluer, more radially arranged leaves (Hatch 2021–2022).

'Oudemansii'

A compact, pyramidal plant selected as a seedling at the Schovenhorst Pinetum, the Netherlands, by den Ouden & Sons in 1940. The first order branches are strongly horizontal, the leaves radially arranged, rather short (1.5–2 cm), a rich bluish-green, though not especially glaucous (Hatch 2021–2022). A tree growing under this name in the Heather Garden, part of the Valley Gardens in Windsor Great Park, UK, was 12 m × 34 cm dbh in 2021 (Tree Register 2023).

Pendula Group

Some permutation of the name ‘pendula’ has been suffixed to Pseudotsuga menziesii since at least 1853. It has been applied to variably pendulous plants rasied from seed, first distinguished at the rank of variety (Abies taxifolia var. pendula Neumann (1853)) with later authors amending Neumann’s variety to the rank of form. Curiously, no combination has ever been published under Pseudotsuga menziesii itself, but many iterations appeared under earlier names such as Abies taxifolia, Pseudotsuga douglasii, P. taxifolia, etc. (Plants of the World Online 2023).

Nurseries later applied the name to more exaggeratedly weeping forms, but even by the late 19th century multiple clones were circulating under the name. Auders & Spicer (2012) advised against the use of the name as a stand alone cultivar and plants belonging to var. menziesii previousy treated as ‘Pendula’ could more logically be placed in Pendula Group. The best pendulous forms now bear unique names (e.g. ‘Cascade’, ‘Glauca Pendula’, ‘Graceful Grace’, and ‘Idaho Weeper’); those belonging to var. menziesii could logically be placed in Pendula Group but their unique names should be maintained, whilst those belonging to var. glauca should probably not be placed in the same group.

'Pine Grove Gold'

A vigorous tree of typical habit, the young spring growth golden-yellow, soon turning pale green, and then darker green by winter. Introduced by the Cedar Ridge Nursery, New Jersey, before 2008 (Auders & Spicer 2012).

'Serpentine'

A slow-growing irregularly contorted plant with twisted branches and branchlets. To 3 m in ten years. Listed by Edwin Smits, the Netherlands in 2009 (Auders & Spicer 2012).

The oddly contorted growth form of Pseudotsuga menziesii 'Serpentine'. Arboretum Trompenburg, the Netherlands. 25 September 2023. Image Tom Christian.

Pseudotsuga menziesii 'Serpentine'. Arboretum Trompenburg, the Netherlands. 25 September 2023. Image Tom Christian.

'Shorty's Blue'

A slow-growing, upright, compact, pyramidal plant with rich blue foliage. In ten years 2 × 1 m. Listed by Bucholz & Bucholz Nursery, Oregon in 2009 (Auders & Spicer 2012).

'Skyline'

A vigorous tree of strong growth with unusual, sparse, curved and twisted branches like Picea abies ‘Virgata’, and with glaucous-green leaves. 3–5 × 1.5–3 m after ten years. Otto Solburger found it as a sport on Skyline Boulevard near Portland, Oregon, sometime before 1986 (Auders & Spicer 2012).

'Slavinii'

A rather small, conical cultivar, densely branched low down with a broad base and narrowing abruptly to a spire like top. The bright green leaves are rather short and crowded on the shoots. To 1.8 × 1.3 m in ten years. Discovered as a seedling in 1914 near Cobb’s Hill Reservoir, Rochester, New York, and named in 1932 for horticulturist Bernard H. Slavin (1873–1960). Jacobson described it as ‘very rare’ by the late 1990s (Auders & Spicer 2012; Jacobson 1996). Apparently the original name was ‘Pyramidata Slavinii’ but Krüssmann shortened it in 1955 (Hatch 2021–2022).

'Slavin's Weeping'

A large tree of strong growth with horizontal first order branches and pendulous second order branches, branchlets etc. Found in the New York State Parks by J.W. Kelly in 1977 (Auders & Spicer 2012).

'Stairii'

A tall tree of normal habit and size with creamy-yellow new growth, turning pale green in summer and darkening in autumn. It was found before 1871 near Castle Kennedy on the Earl of Stair’s estate in Wigtownshire, Scotland (Auders & Spicer 2012; Bean 1976). The tree illustrated below, growing at Cortachy Castle in Angus, Scotland, was 28 m × 60 cm dbh in 2017; the largest confirmed example known in the UK (Tree Register 2023).

Pseudotsuga menziesii 'Stairii' at Cortachy Castle, Angus, UK. 28 July 2004. Image Derek Spicer.

'Standishiana Fastigiata'

Branches spreading at the base then turning upwards forming a column (Auders & Spicer 2012). Recoreded by Sénéclauze in 1867.

'Standishii'

A tree raised c. 1855 in the Standish Nursery, UK ‘from English seed’ according to Auders & Spicer (2012). Its distinguishing features are not recorded, but it may be that, at the time, raising Douglas Fir from home grown seed was deemed sufficiently novel to provide a unique moniker for marketing purposes. In the absence of any distinguishing features the name has long been superfluous.

'Stricta'

A slow-growing, very narrow plant with first order branches rising at a steep angle, themselves branching near their tips. In many respects it is another iteration of ‘Fastigiata’ but of distinct origin, having been raised in France by Sénéclauze c. 1862 (Auders & Spicer 2012).

'Suringarii'

There is some uncertainty regarding the distinguishing features of this plant, discovered in 1927 by von Schwerin in the park at Renkum, near Wageningen, The Netherlands. Auders & Spicer (2012) suggest a potentially large tree of normal habit but with the needles all curved downward beneath the plane of the shoot, while Hatch (2021–2022) suggests it is the branches that curve back on themselves. Perhaps it was both. We may never know for sure as it appears it was never propagated and the original tree destroyed in a bombing raid in 1944 (Hatch 2021–2022).

'Taranto'

Described by Auders & Spicer (2012) as ‘a very tall-growing cultivar with a straight trunk, downward curving branches and bluish green needles’ it seems doubtful that this cultivar differs in any significant way from the type. The name may originally have been applied simply to identify a seed source, in this case the famous gardens of Villa Taranto on Lake Maggiore, northern Italy.

'Thrift'

A broadly pendulous plant with blue-green foliage, up to 1.5 tall and broad in ten years. Raised in the United States by Mark Dusek in 1980 (Auders & Spicer 2012).

'Torquis'

An upright plant with curving, twisting, undulating, at times corkscrew-like branches with normal deep green foliage. In ten years 3 × 2 m. Considered by Auders & Spicer (2012) to be ‘a hybrid between var. menziesii and var. glauca’; they add that it was ‘found in a seed bed near Grangeville, Idaho, USA c. 1975 by Pat Wells’.

'Uwe's Golden'

A promising selection for those who like golden conifers, ‘Uwe’s Golden’ is a vigorous plant of typical habit, capable of 4 × 1.5 m in ten years, but with golden yellow foliage all year round. It should be positioned in full sun for the best colour. Raised in Germany before 1999 by Günther Horstmann, Germany, and named for his son (Auders & Spicer 2012).

var. glauca (Beissn.) Franco

Pseudotsuga menziesii var. glauca – the Interior, Blue, Rocky Mountain or Colorado Douglas Fir – occurs more or less continuously in the Rocky Mountains, from British Columbia south to New Mexico, and then in increasingly isolated populations in diverse habitats as far south as the highlands of Oaxaca in south-central Mexico; there are just two small areas of overlap with var. menziesii, in southern British Columbia and northeastern Washington (see taxonomic note). It is otherwise well differentiated from the type by its distribution and ecology, and is usually easily distinguished by its smaller, stiffer stature, shorter, more colourful cones with reflexed to spreading bracts, and its sturdier leaves that vary from dull grey-green to intensely glaucous (Debreczy & Rácz 2011; Lipscomb 1993).

In cultivation it is a combination of these characters that will help determine the identity of trees where both varieties are known to occur, for example while generally a smaller tree than var. menziesii, var. glauca can grow to significant size in the right conditions; a wild tree growing in Clearwater County, Idaho, was measured at 63.7 m × 1.8 m dbh in 1991 (Jacobson 1996) while in cultivation there are examples to 38 m in Štěkeň Castle in Czechia (measured in 2018; monumentaltrees.com 2023) and to 35 m in Cumbria, UK (measured in 2013; Tree Register 2023).

Historically, the horticultural narrative has suggested that the two varieties of Douglas Fir have such distinct distributions in two highly differentiated climate zones (oceanic and continental) that where one will thrive the other will not. Certainly it is var. menziesii that dominates in climates with a strong oceanic influence, such as across a large swathe of western Europe, while var. glauca dominates across most of North America, from its native range in the Rockies through the midwest and into the northeast, and in continental areas of central, eastern and northern Europe, but there are plenty of examples of both varieties that flout this rule, especially of var. menziesii in continental Europe and of var. glauca in maritime Europe (monumentaltrees.com 2023; Tree Register 2023). It might be that var. glauca gathered from or near to the areas where it overlaps with var. menziesii fares better in a maritime climate than material from the American Rockies (whence most horticultural stock is derived, especially in the US) but this does not seem to have been investigated. The situation becomes more nuanced when we consider Mexican material.

The more or less disjunct populations in Mexico, which become more isolated the further south one finds them, have been treated as distinct at various ranks, reflected in the list of synonyms given above. Many of these names were published by Fernande Flous who proposed twelve new Pseudotsuga species in North America during the 1930s, six of them in Mexico. This excessive splitting – ‘based on cone characters that proved poorly formulated and unreliable’ (Grimshaw & Bayton 2009) – prompted a highly conservative counter treatment by Little (1952) reducing North American Pseudotsuga to just P. macrocarpa and P. menziesii. A little earlier, in 1945, the Mexican botanist Maximino Martínez had plotted a more conciliatory course and accepted four of Flous’s species: P. flahaultii, P. guinieri, P. macrolepis and P. rehderi, but while at least some of these names remained in use through the rest of the 20th century, by the 21st most works were in agreement that all Mexican Pseudotsuga diversity falls within the variation of P. menziesii var. glauca (e.g. Farjon 2017; Adams et al. 2013; Debreczy & Rácz 2011; Wei et al. 2010; Lipscomb 1993).

Some alternative approaches persist, however. In New Trees Grimshaw & Bayton (2009) recognised Pseudotsuga lindleyana (Roezl) Carrière (an older name for P. macrolepis Flous) on account of its ‘easily distinguishable appearance both in the wild and in cultivation’ and on the basis of the ‘preliminary genetic studies’ of Li & Adams (1989) whose results suggested that P. lindleyana was amply distinct and sister to the whole of P. menziesii. P. guinieri Flous was sunk into this concept of P. lindleyana, along with P. menziesii var. oaxacana Debreczy & Rácz, described in 1995 to accomodate new populations discovered in Oaxaca in 1994, extending the range of North American Pseudotsuga some 200 km further south from its previously understood southern limit in northern Puebla. When Pseudotsuga lindleyana is recognised its range extends from the southern limit for the genus in Oaxaca at 16°N, north through the Sierra Madre Occidental, Sierra Madre Oriental and (rarely) the Sierra Madre del Sur to an uncertain terminus somewhere in northern Mexico (Grimshaw & Bayton 2009); across much of the northern part of this area it overlaps with P. menziesii var. glauca (Debreczy & Rácz 2011). Many of the morphological differences across Mexican populations, such as growth form and glaucousness of leaves and cone bracts, are variable and most likely related to climate, while the results of more recent studies examining chloroplast and nuclear ribosomal DNA have not supported taxonomic differentiation (Adams et al. 2013) thus even where populations appear distinct, these are nothing more than ecotypes, reflecting the variability inherent in a taxon distributed over an extensive and ecologically diverse range (Debreczy & Rácz 2011).

Pseudotsuga menziesii var. glauca was probably discovered for modern botany ‘in the outer ranges of the Rocky Mountains’ by Parry in 1862 (Elwes & Henry 1906–1913). Seed was sent to the Arnold Arboretum the following year and proved perfectly hardy there. Several trees, traceable to an 1874 Parry introduction, still grow at the Arnold, the largest 87 cm dbh (Arnold Arboretum 2023). Historically var. menziesii had never been able to withstand the Arnold’s continental climate, whether from wild-collected seed or from seed gathered from trees grown successfully in Europe (Elwes & Henry 1906–1913) but several recent collections, mostly by Kyle Port, are showing some promise; coming from a diverse range of provenances it is likely that a changing climate is the key factor in their success (Arnold Arboretum 2023). It is not clear when var. glauca was introduced to European cultivation, but Roezl apparently sent seed from Mexico in 1856 as ‘P. lindleyana’ which even in 1909 Elwes and Henry ascribed to var. glauca, observing ‘plants raised from these seeds on the continent do not seem to differ from the Colorado Douglas’ (Elwes & Henry 1906–1913), but beyond noting var. glauca’s more even germination and greater hardiness, few 19th or early 20th century European observers seem to have documented it at any length, perhaps distracted by the unprecedented success of the type.

More recent introductions are better recorded. A number of Mexican trees, especially conifers, were introduced to the UK in the 1960s as part of a seed exchange between the Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias and the Forestry Commission. Pseudotsuga menziesii var. glauca was introduced in 1963 (as P. macrolepis) from seed collected at c. 2800 m near Tlaxco, Tlaxcala. Trees survive from this introduction in several English collections, but the tallest at Bicton Park Botanical Gardens, Devon, 15 m in 2001 and 18 m × 42 cm dbh in 2013, had gone by 2017 (Johnson 2003; Tree Register 2023; TC pers. obs.). In New Trees, John Grimshaw observed that trees raised from this introduction ‘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’ (Grimshaw & Bayton 2009).

Another introduction, part of the same 1963 exchange, was made under the name Pseudotsuga flahaultii , originating from near Saltillo in northern Mexico. Of these John Grimshaw noted ‘These trees, planted in the same arboreta, differ conspicuously from [the collection introduced as P. macrolepis] in their denser foliage with somewhat longer, strongly glaucous blue-green leaves’ and in this respect match trees raised from Frankis 149, gathered at 3000 m asl ‘on the moist east flank of Cerro Potosí in Nuevo León’ (Grimshaw & Bayton 2009). This introduction is, possibly, the same source of several trees cultivated at Arboretum Hørsholm in Denmark, accessioned in 1965. Also growing at Hørsholm are plants raised from Frankis 149, where the notes record that this introduction was made under the name P. guinieri (University of Copenhagen 2023).

Pseudotsuga menziesii var. glauca is adapted to drier and colder conditions than the coastal variety, but in the UK the best specimens are still to be found in wet, Atlantic microclimates. This (relatively) tall example, 35 m in June 2013 when the photograph was taken, grows at Brockhole in Cumbria. Image Owen Johnson.

Developing seed cones on Pseudotsuga menziesii var. glauca at Bluebell Arboretum, Derbyshire, UK. July 2018. Image Tom Christian.

The best blues in Pseudotsuga menziesii var. glauca are revealed in a warm, relatively dry climate or in young trees. Bluebell Arboretum, Derbyshire, UK. July 2018. Image Tom Christian.

Foliage on Pseudotsuga menziesii var. glauca Frankis 149, accession 1992.0785*A at the Sir Harold Hillier Gardens, UK (3 April 2015). This collection is considered by some to belong to a separate taxon, P. lindleyana, which here is considered synonymous with P. menziesii var. glauca. Image © Jan De Langhe - Arboretum Wespelaar.

Foliage above and below shoot on Pseudotsuga menziesii var. glauca Frankis 149, accession 1992.0785*B (Sir Harold Hillier Gardens, UK – 3 April 2015). Image © Jan De Langhe - Arboretum Wespelaar.

Foliage below shoot on Pseudotsuga menziesii var. glauca Frankis 149, accession 1992.0785*A (Sir Harold Hillier Gardens, UK – 3 April 2015). Image © Jan De Langhe - Arboretum Wespelaar.

Short dull green needles on Pseudotsuga menziesii var. glauca Frankis 149, accession 1992.0785*B (Sir Harold Hillier Gardens, UK – 3 April 2015). Image © Jan De Langhe - Arboretum Wespelaar.

Young seed cones on Pseudotsuga menziesii var. glauca at Pinetum Antoine, Belgium (19 September 2010). Image © Jan De Langhe - Arboretum Wespelaar.

'Variegata'

A tree of typical habit but with pale green leaves, the upper third to two thirds yellowish, appearing chlorotic. Susceptible to sunscorch. Raised at Dupplin Castle, Perthshire, Scotland, by 1871 but probably lost to cultivation (Auders & Spicer 2012).

'Viminalis'

A tall tree with horizontal snake-like branches which bare entirely pendulous branchlets. Discovered by von Schwerin growing in Charlottenlund Forest near Copenhagen, Denmark, in 1919 (Auders & Spicer 2012).

'Weep Willie'

A weeping plant that will form a ground-hugging mat when grafted very low, but when grafted high it can probably be trained to a desired height. Annual growth up to 20 cm. Found in the USA before 2000 by Jerry Morris (Auders & Spicer 2012; Hatch 2021–2022).

'Whiskey Hill'

A vigorous, slightly twisted, selection of pyramidal habit and with green leaves. Listed by Neuschwander’s Nursery, Whiskey Hill Road, Oregon in 1996 (Auders & Spicer 2012).

'White Mountain Weeping'

A pendulous clone with blue leaves, listed by Coenosium Gardens, Washington, USA in 1982 (Auders & Spicer 2012).

'Wicky's Pinnacle'

A strongly weeping selection which with staking can reach 4 × 1 m in ten years. It was raised from seed by Bob Wickham, Te Kuti, New Zealand and commercialised by Cedar Lodge Nursery in 2007 (Auders & Spicer 2012).

'Wind Surfer'

A somewhat upright plant with long branches which sweep downward and trail across the ground, the shape likened to a wave. Listed by Collector’s Nursery, Washington, USA in 2001 (Auders & Spicer 2012).

'Wycoff's Big Blue'

A vigorous pyramidal selection with bright glaucous foliage, it can grow to 3.5 × 2 m in ten years and is one of the best blues for Hatch (2021–2022) along with ‘Blue Wonder’ and ‘Hess Blue’. It was found by Hugh Wycoff on a Christmas tree farm near Laura, Illinois in 1955 and listed in 1988 by Chub Harper (Auders & Spicer 2012).