Sitka spruce

Description

Picea sitchensis, the Sitka spruce, is a large, coniferous, evergreen tree growing to almost 100 meters (330 ft) tall, with a trunk diameter at breast height that can exceed 5 m (16 ft). It is by far the largest species of spruce and the fifth-largest conifer in the world (behind giant sequoia, coast redwood, kauri, and western red cedar), and the third-tallest conifer species (after coast redwood and coast Douglas fir). The Sitka spruce is one of the few species documented to exceed 90 m (300 ft) in height.Its name is derived from the community of Sitka in southeast Alaska, where it is prevalent. Its range hugs the western coast of Canada and the US, continuing south into northernmost California. The bark is thin and scaly, flaking off in small, circular plates 5–20 centimeters (2–8 in) across. The inner bark is reddish-brown.The crown is broad conic in young trees, becoming cylindric in older trees; old trees may not have branches lower than 30–40 meters (98–131 ft). The shoots are very pale buff-brown, almost white, and glabrous (hairless), but with prominent pulvini. The leaves are stiff, sharp, and needle-like, 15–25 millimeters long, flattened in cross-section, dark glaucous blue-green above with two or three thin lines of stomata, and blue-white below with two dense bands of stomata. The cones are pendulous, slender cylindrical, 6–10 cm (2+1⁄2–4 in) long and 2 cm (3⁄4 in) broad when closed, opening to 3 cm (1+1⁄4 in) broad. They have thin, flexible scales 15–20 mm (5⁄8–3⁄4 in) long; the bracts just above the scales are the longest of any spruce, occasionally just exserted and visible on the closed cones. They are green or reddish, maturing pale brown 5–7 months after pollination. The seeds are black, 3 mm (1⁄8 in) long, with a slender, 7–9 mm (1⁄4–3⁄8 in) long pale brown wing. DNA analysis has shown that only P. breweriana has a more basal position than Sitka spruce to the rest of the spruce. The other 33 species of spruce are more derived, which suggests that Picea originated in North America.