Picea retroflexa / Green dragon spruce

Picea retroflexa, as described in 1906 by Maxwell Tylden Masters (1833–1907), in Journal of the Linnean Society, Botany 37th edition, is commonly known as green dragon spruce, as well as 鳞皮云杉 (Lín pí yún shān / scaly spruce) in the Chinese language. Masters (1906) states that pulvini on the shoots are bent back along the shoot axis (patenti-reflexi); this may be the origin of the epithet retroflexa. However his description also states "very remarkable in its sharply decurved cone-scales", so the epithet may also allude to that character.

Description. Green dragon spruce is an evergreen coniferous species of tree that grows to mature heights of 150 feet (45 m) tall; with a trunk up to 60 inches (150 cm) in diameter, measured at breast height; with a single straight, round trunk and a conical to columnar crown of numerous short, straight, horizontal primary branches.

  • Bark is rough and scaly, comprised of small, flaky plates.
  • Twigs are short and thick, light- or orange-brown in color, strongly ridged and grooved with conspicuous pulvini that measure 0.04 to 0.08 inch (1 - 2 mm) long and 0.04 to 0.06 inch (1 - 1.5 mm) wide.
  • Foliar buds are broadly conical and resinous, measuring 0.2 to 0.4 inch (5 - 10 mm) long and wide, closely surrounded by curved leaves. Foliar buds are composed of keeled, appressed, orange-brown bud scales that persist for several years at the base of the shoot.
  • Leaves (needles) are light- to glaucous-green in color, radially spreading, and curved forward. Individual needles measure 0.48 to 0.72 inch (12 - 18 mm) long and 0.06 to 0.08 inch (1.5 - 2 mm) wide, with a linear outline, a quadrangular cross-section, prominent ribs, and sharply pointed apices, with stomata in paired bands of 2 to 3 lines on upper surfaces and 4 to 6 lines on lower surfaces.
  • Pollen cones are borne axillary. They measure 1.2 to 2 inches (3 - 5 cm) long, ripening reddish yellow.
  • Seed cones are borne terminal on branchlets, initially erect becoming pendulous. They are sessile, with oval-oblong to cylindric-conical/obtuse shape, measuring 3.2 to 5.2 inches (8 - 13 cm) long and 0.8 to 1.6 inches (2 - 4 cm) wide when fully open. Cone color is purple-red when immature, maturing to purple-brown.
  • Seed scales have and obovate shape, measuring 0.6 to 0.8 inch (15 - 20 mm) by 0.48 to 0.6 inch (12 - 15 mm) at mid-cone, lower surfaces are striated and shiny, outer margins are slightly erose or denticulate, and straight to reflexed when open.
  • Bracts measure 0.2 to 0.24 inch (5 - 6 mm) long, included.
  • Seeds have ovoid-oblong shape, measuring 0.12 to 0.16 inch (3 - 4 mm) long, colored dark brown, with a 0.4 to 0.6 inch (10 - 15 mm) long and 0.2 to 0.28 (5 - 7 mm) wide pale-brown obovate-shaped wing.
Distribution. This species is native to China — western Sichuan, and southeastern Xizang provinces, where it is found in the subalpine zone at elevations of 6,600 to 13,300 feet (3,000 - 4,000 m) above sea level, occasionally to 15,500 (4,700 m), mostly on northern aspects with acid soils. The climate there is described as continental: relatively dry. Common associates at lower elevations include P. likiangensis var. rubescens, P. asperata var. aurantiaca, Abies chensiensis, Tsuga chinensis, and Betula albo-sinensis; at higher elevations it commonly grows with Abies squamata.

Hardy to USDA Zone 7, cold hardiness limit between 0º to 10ºF (-17.7° and -12.2°C).

Attribution from: Aljos Farjon; , A Handbook of the World's Conifers; ©2010, Brill Academic Publishers, Leiden, The Netherlands.

Picea retroflexa — Green Industry Images; copyrighted photograph; permission granted.
Photo by Ernie Wiegand
Picea retroflexa — a closeup of foliage and mature seed cones.
Photo by John Gagstrom at Morton Arboretum, Illinois
Picea retroflexa — a closeup of a mature seed cone.
Photo by John Gagstrom at Morton Arboretum, Illinois
Picea retroflexa — a closeup of foliage.
Photo by John Gagstrom at Morton Arboretum, Illinois
Picea retroflexa — a closeup of foliage.
Photo by John Gagstrom at Morton Arboretum, Illinois

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