Cupressus dupreziana A. Camus

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Credits

Article from New Trees, Ross Bayton & John Grimshaw

Recommended citation
'Cupressus dupreziana' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/cupressus/cupressus-dupreziana/). Accessed 2021-09-21.


var. atlantica (Gaussen) Silba

Common Names
Atlas Cypress

Synonyms
C. atlantica Gaussen
C. sempervirens L. var. atlantica (Gaussen) Silba

The crown of var. atlantica is typically rather narrow and conical, unlike the broad crown of the type variety, though environmental factors may be important. The cones have only four pairs of seed scales and the seed wings are narrow. Farjon 2005c. Distribution MOROCCO: southern Atlas Mts. over an area of 200 km2, in particular the Oued N’fiss valley. Habitat Dry woodland on steep scree slopes between 1100 and 2000 m asl. The climate is essentially Mediterranean with 350–700 mm annual precipitation and a temperature range of –15 ºC to 30 ºC. USDA Hardiness Zone 7. Conservation status Endangered. Cross-reference S203 (as C. sempervirens var. atlantica).

Although from a slightly more convenient area than the Sahara Cypress, the Atlas Cypress is also rare in cultivation. Recent collections have, however, been made by expeditions from the Royal Botanic Garden Edinburgh. At Kew there is a very narrow specimen of about 10 m dating from 1980, when it was received from Edinburgh, from an original collection by Milde Arboretum of Bergen, Norway.


var. dupreziana Sahara Cypress

Tree to 20 m, 3(–4) m dbh. Bark greyish or reddish brown, with deep longitudinal fissures. The crown of mature, wild specimens is often contorted and mutilated by wind and sand storms, and grazing animals; in cultivation, young specimens are somewhat conical or bushy, and develop a broad, rounded crown. Branchlets typically decussate, though initially flattened on one plane. Juvenile leaves needle-like, with extremely active leaf resin glands; mature leaves scale-like, dull green or slightly glaucous, decussate, appressed, densely crowded; the lateral and facial pairs are similar, 0.1–0.15 cm long, apex acute; leaf resin glands abaxial, elongated and somewhat inconspicuous, except on very old leaves. Male strobili solitary and terminal, borne on short, lateral branches, yellow, 0.6 × 0.3 cm, subglobose, with 12 peltate microsporophylls. Female cones axillary, usually solitary, ovoid to oblong, valvate, 1.8–2.4 × 1.6–2 cm, dull grey or reddish brown. Seed scales in five to six (to nine) decussate pairs, valvate and rather thin; umbo rounded. Seeds reddish brown, spherical and flattened, 0.4–0.5 × 0.5–0.6 cm; seed wings thin and to 0.2 cm wide. Seedlings retain juvenile leaves for several years. Farjon 2005c. Distribution ALGERIA: Tamrit Plateau of the Tassili N’Ajjer massif. Habitat Wadis in the central Sahara, between 1000 and 1800 m asl. Temperatures can range between –7 ºC and 30 ºC, and precipitation is minimal, though highly variable (mean annual precipitation 18 mm). USDA Hardiness Zone 7. Conservation status Critically Endangered. This taxon is entirely restricted to the Tamrit Plateau, where only 153 living specimens remain. Successful reproduction and seedling establishment is rare (only three known seedlings), and the plants are threatened by overgrazing and overexploitation for firewood (Stewart 1970). In the past the climate of the Sahara was much wetter, as evidenced by the few remaining populations of Nile Crocodiles, which still exist in some areas. Cupressus dupreziana var. dupreziana, like the crocodiles, is probably a relict of that period. Illustration NT291, NT296. Cross-references S203 (as C. sempervirens var. dupreziana), K105.

Coming from one of the least accessible parts of the world (physically and politically), and one of the harshest climates, it is not surprising that the Sahara Cypress is rather scarce in the world’s arboreta. On the other hand, there is a considerable challenge factor in going to Tassili N’Ajjer to find it, and this has obviously proved tempting on several occasions, resulting in striking photographs of picturesque gnarled trees growing in a barren rockscape. Once the challenge of collection has been met, the species seems to present no particular difficulty in cultivation. There is a group of trees at Kew, all ultimately derived as cuttings from a collection made in about 1970 by Mrs Pawluk. They are dull green in colour, and all narrowly columnar with very tightly packed shoots. In the British Isles the tallest specimen (11.8 m) is at the Hillier Gardens, where there is also another of 8 m (TROBI). The species has clear landscape potential for difficult dry places, having a strong resemblance (and close relationship) to Cupressus sempervirens, from which both subspecies of C. dupreziana can be distinguished by the presence of resin secreted by active glands on their leaves (Rushforth 1987a).

Staff at the Botanic Garden of Smith College, Massachusetts, where C. dupreziana is grown under glass, from collections made in the Tassili mountains in 1985, have studied the propagation of the species from cuttings. Rooting is best when cuttings are treated with a 24-hour soak in low concentrations of indolebutyric acid, and placed under intermittent mist at 15–25 ºC, with bottom heat (Smith College 2005b).