Abies concolor (Gordon) Lindl. ex Hildebr.

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Article from Bean's Trees and Shrubs Hardy in the British Isles

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'Abies concolor' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/abies/abies-concolor/). Accessed 2020-10-23.

Genus

Common Names

  • Colorado Fir
  • White Fir
  • Rocky Mountain Fir

Synonyms

  • Picea concolor Gord.

Glossary

apex
(pl. apices) Tip. apical At the apex.
branchlet
Small branch or twig usually less than a year old.
cone
Term used here primarily to indicate the seed-bearing (female) structure of a conifer (‘conifer’ = ‘cone-producer’); otherwise known as a strobilus. A number of flowering plants produce cone-like seed-bearing structures including Betulaceae and Casuarinaceae.
glabrous
Lacking hairs smooth. glabrescent Becoming hairless.
glaucous
Grey-blue often from superficial layer of wax (bloom).

References

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Credits

Article from Bean's Trees and Shrubs Hardy in the British Isles

Recommended citation
'Abies concolor' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/abies/abies-concolor/). Accessed 2020-10-23.

Trees 20-40 m tall, to 1 m dbh. Crown narrowly conical, broadening with age. Bark of young trees smooth, grey or whitish with conspicuous resin blisters, becoming greyish or yellowish or pinkish brown in old trees, scaly and deeply fissured low down. First order branches curved, relatively short, in regular whorls borne horiztontally in young trees, lower branches later drooping, second order branches spreading. Branchlets slender, yellowish or olive green at first, occasionally orange-brown, soon becoming grey brown, smooth or with shallow grooves, glabrous, or with minute yellowish pubesence on first year branchlets. Vegetative buds globose, 3-5 mm long, very resinous. Bud scales ovate-triangular, brown, persistent for 2-3 years. Leaves (1.5-)4-6(-9) cm x 2-3 mm, radially spreading on shaded shoots, shorter, curved and somewhat assurgent otherwise, especially in upper branches, evenly covered on both surfaces with stomata in indistinct bands, pruinose grey-green, midrib green beneath. Seed cones 7-12 x 3-4.5 cm long, cylindrical, pale olive-green or purplish, later yellow-brown then pale-brown, with fully included bracts, sessile. (Debreczy & Rácz 2011Farjon 2017Hunt 1993).

Distribution  Mexico Chihuahua, Sonora United States Arizona, California, Colorado, Idaho, Nevada, Utah, Wyoming

Habitat Typically in open sub-alpine woodland locally associating with Pinus aristata, but at lower elevations in mixed forests with Picea engelmanii, Picea pungens, Pseudotsuga menziesii, Quercus gambelii. 1700-3400 m asl.

USDA Hardiness Zone 3-7

RHS Hardiness Rating H6

Conservation status Least concern (LC)

A tree 80 to 100 ft high in nature; young shoots yellowish, patched with minute down, or glabrous; buds very resinous, egg-shaped, rounded at the top. Leaves glaucous green, 1 to 3 in. long, 112 to 110 in. wide; tapered at the base, rounded (with sometimes a slight notch) at the apex; otherwise of even width, not grooved above. There are not very conspicuous lines of stomata on both surfaces; they cover the whole centre of the leaf above, but beneath they are in two bands. The leaves are mostly aggregated into two opposite sets, but on the upper side of the branchlet there are a number of leaves pointing upwards, and beneath some pointing downwards; the arrangement therefore is irregular, and the upper leaves are considerably the shorter. On cone-bearing shoots the leaves generally are shorter and stouter and curve upwards. Cones about 4 in. long, 112 to 134 in. wide, of a rich plum colour, as I have seen them in Waterers’ nursery at Knap Hill, turning brown with age; bracts enclosed by the scales.

Native of Colorado, Arizona, New Mexico, and Utah (but see var. lowiana); discovered in 1847 and introduced in 1872. It is one of the most beautiful of all conifers and grows almost as well in southern England as it does in the moister and cooler parts of the country. The best recorded are: Cragside, Northumb., 131 × 1112 ft (1958); Benmore, Argyll, 131 × 912, 128 × 1114, and 124 × 934 ft (1956); Blair Atholl, Perths., 127 × 934 ft (1955); Eridge Castle, Kent, 118 × 1114 ft (1963). There are also big trees at Westonbirt and Batsford, Glos., and at Dropmore, Bucks.

Footnotes

Cultivated trees considered to be hybrids between A. concolor and A. grandis have been reported from Belgium and Germany.


f. violacea (A. Murr.) Beissn

This name applies in general to trees with leaves of a particularly silvery-glaucous tinge; such forms occur in nature and in seed-beds.

var. lowiana (Gord.) Lemm.

Common Names
Low's Fir
Sierra White Fir
Pacific White Fir
California White Fir

Synonyms
Abies lowiana (Gordon) A. Murray
Abies concolor subsp. lowiana E. Murray
Abies concolor var. baja-california Silba

As a western vicariant of A. concolor distributed in the Southern Cascades, the Coast and Sierra Nevada Ranges, var. lowiana has been characterised by several authors as being intermediate betwen A. concolor (to the south and east) and A. grandis (to the north), and is probably no more than an expression of the cline that exists between the two. (Debreczy & Rácz 2011, Rushforth 1987a). Unsurprisingly it exhibits affinities with both these species, appearing more grandis-like in the north, and more concolor-like in the south, though cultivated trees are ‘usually quite distinct from both’ (Mitchell 1972).

From the description given for A. concolor s.s. the var. lowiana differs in several respects, notably: Trees (20-40-)60-70 m tall, (1-)2-2.5 m dbh. Branchlets orange-yellow, smooth, glabrous or slightly pubescent when young, usually grey and fully glabrous later. Leaves may be either pectinately outspreading in shade branchlets (as in A. grandis) or rising either side of shoot to form a ‘V’, always at least somewhat glaucous on both sides (unlike A. grandis), with two faint stomatal bands beneath and with incomplete stomatal bands on the upper surface (unlike A. grandis); more assurgent and usually with stomata evenly distributed on both sides of the needle in upper and fertile branches. (Debreczy & Rácz 2011, Hunt 1993).

Distribution

  • Mexico – Baja California Norte
  • United States – California, Oregon

RHS Hardiness Rating: H6

Taxonomic note Based on examination of herbarium sheets during the 1980s covering ‘much of the range’ of A. concolor s.l., Farjon concluded that there is ‘no taxonomically sound basis upon which to recognise [var. lowiana] as a distinct species or as an infraspecific taxon’ (Farjon 2017). Debreczy & Rácz (2011) take a different view, recognising the entity lowiana at species rank. This position is also adopted by Hunt (1993) for the Flora of North America account, although it must be noted that both of these works apply narrow circumscriptions. Trees fitting the traditional understanding of var. lowiana are important forest trees in the wild, as well as being common in cultivation, perhaps even more so than the type, and so it seems that the best compromise is to continue to recognise var. lowiana in order to faciliate discussion. In the UK, the RHS uses the name Lowiana Group to circumscribe trees fitting this description (Edwards & Marshall 2019) and this is another approach that could be considered. Populations in Baja California Norte have previously been discussed as A. concolor var. baja-california Silba. Debreczy & Rácz (2011) refer these populations to their concept of A. lowiana, although they qualify their treatment with a discussion of the xeromorphic nature of these populations and the implications of this on morphological expression, they conclude that it is ‘clearly [connected] with the Oregon-California taxon’ (Debreczy & Rácz 2011). Provenance would seem to have a significant bearing on the success, or otherwise, of A. concolor s.l. in cultivation, particularly in oceanic climates. It seems unlikely that material from the Baja California Norte populations is represented in cultivation in our area, and even if it was it would be unlikely to perform well, hence these do not merit further discussion here.

As seen in gardens, this fir is well distinguished from cultivated specimens of A. concolor and indeed has long been grown as a distinct species. The distinguishing characters of the “A. lowiana” of reference books are found mainly in the foliage: the middle line of erect leaves seen in ‘typical’ concolor is absent, the leaves lying pectinately in one plane, or directed upward and outward in a V-shaped arrangement. It is also said to have a separate area of distribution, being confined to the ranges near the Pacific, from Oregon into the Sierra Nevada (cf. the distribution of A. concolor). However, American botanists are for the most part reluctant to concede even varietal status to this fir, preferring to regard it as a phase of A. concolor, included within the natural span of variation of that species. Here, following the Kew Hand-list, it is treated as a variety.A. F. Mitchell of the Forestry Commission has observed that the trees cultivated in this country are of two forms. The first has a rectangular crown, is often forked, and has a dark, not markedly corky bark; its leaves recall A. grandis, being flatly arranged, long, and quite green. These are likely to have originated from Oregon. The second form, probably from the Sierra Nevada, approaches A. concolor as seen in cultivation; it is conical-crowned, forks only at a great height, and has a thick, corky, paler brown bark; leaves partly assurgent, bluish green, with stomatal bands above.This variety, if such it be, has attained a good height in cultivation. For the most part, the best specimens are in areas of high rainfall but the thriving tree in the National Pinetum, Bedgebury, Kent, suggests that it is a fairly amenable fir. This tree is of the second form described above; planted 1925 it measured 86 × 9 ft in 1965. Of this form the two best recorded are: Durris House, Kinc., 145 × 14{1/4} ft (1955), and Bodnant, Denbigh, pl. 1886, 133 × 11{1/2} ft (1966). Others of 125 ft and over are at Dupplin, Perths.; Cragside, Northumb.; Oakley Park, Shrops.; and Westonbirt, Glos. The first form, with the “grandis” type of foliage (see above), is represented by trees of 115 ft and over at Rammerscales, Dumf.; Monk Hopton, Shrops.; and Brockhall, Northants. Two others of this form whose planting dates are known are: Youngsbury, Herts., pl. 1866, 108 × 7 ft; and Castle Milk, Dumf., pl. 1886, 113 × 9 ft (both 1966).


'Wattezii'

Leaves silvery-yellow when young; of Dutch nursery origin.

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