The Sitka Spruce (Picea sitchensis) is a large coniferous Evergreen tree growing to 50–70 m tall , exceptionally to 100m tall, and with a trunk diameter of up to 5 m, exceptionally to 6–7 m diameter.
The bark is thin and scaly, flaking off in small circular plates 5–20 cm across. The crown is broad conic in young trees, becoming cylindric in older trees; old trees may have no branches in the lowest 30–40 m. 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 mm 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 long and 2 cm broad when closed, opening to 3 cm broad. They have thin, flexible scales 15-20 mm 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 long, with a slender, 7–9 mm long pale brown wing.
Sitka Spruce is a long-lived tree, with individuals over 700 years old known. Because it grows rapidly under favorable conditions, large size may not indicate exceptional age.