Picea abies

Picea abies, called Norway spruce or European spruce, is native to Northern, Central, and Eastern Europe. Its branchlets tend to droop, and it produces the longest cones of any spruce species, measuring 9–17 cm. It is very closely related to Siberian spruce (Picea obovata), which takes over east of the Ural Mountains, and the two hybridize freely. This spruce is widely planted for timber and is used as a Christmas tree in many countries. It was also the first gymnosperm to have its genome sequenced. The Latin name *abies* means "like a fir tree."

The tree is large and fast-growing, reaching 35–55 m tall with a trunk diameter of 1–1.5 m. Under good conditions, it can grow up to 1 m per year for its first 25 years, then slows after surpassing 20 m. Its shoots are orange-brown and smooth. The needle-like leaves are 12–14 mm long, blunt-tipped, quadrangular in cross-section, and dark green on all sides with faint stomatal lines. The seed cones, the longest of any spruce, are 9–17 cm long with bluntly to sharply triangular scale tips. They start green or reddish and turn brown 5–7 months after pollination. The black seeds are 4–5 mm long with a pale brown wing of 15 mm. The tallest measured Norway spruce, at 62.26 m, grows near Ribnica na Pohorju, Slovenia.

Its range spans Europe from Norway and Poland eastward, through the mountains of central Europe, southwest to the western Alps, and southeast through the Carpathians and Balkans to northern Greece. The northern limit reaches just above 70° N in Norway. The eastern boundary in Russia is unclear due to extensive hybridization with Siberian spruce, but is usually set at the Ural Mountains. Trees with Siberian spruce traits appear as far west as northern Finland, with a few in northeast Norway. The hybrid, *Picea × fennica* (or *P. abies* subsp. *fennica*), can be identified by hairy shoots and cones with smoothly rounded scales. The tortrix moth *Cydia illutana* feeds on Norway spruce cone scales, while *Cydia duplicana* feeds on bark near injuries or cankers.

Populations in southeastern Europe tend to have longer cones with more pointed scales, sometimes classified as *Picea abies* var. *acuminata*, though variation overlaps widely with other trees. Some botanists treat Siberian spruce as a subspecies of Norway spruce; typical forms are distinct, with Siberian spruce having cones only 5–10 cm long, smoothly rounded scales, and hairy shoots. Genetically, the two are extremely similar and may be considered closely related subspecies. Another spruce with smoothly rounded cone scales and hairy shoots, also with thicker, blue-green leaves, occurs rarely in the Central Alps of eastern Switzerland. Many texts treat it as a Norway spruce variant, but it appears more closely related to Siberian spruce, Schrenk's spruce, and Morinda spruce. As a distinct species, it is called Alpine spruce (*Picea alpestris*). It hybridizes extensively with Norway spruce, and pure specimens are rare; hybrids are often called Norwegian spruce, not to be confused with pure Norway spruce.

Norway spruce is one of the most widely planted spruces, both within and outside its native range, and is economically important in Europe. It is used ornamentally in parks and gardens and is widely planted as a Christmas tree. Each year, Oslo provides a Norway spruce to London (for Trafalgar Square), Edinburgh, and Washington, D.C., as thanks for aid during World War II. In North America, it is widely planted in the Northeastern, Pacific Coast, and Rocky Mountain states, and in southeastern Canada, and has naturalized from Connecticut to Michigan and elsewhere. It prefers cool summers and grows up to USDA Zone 7, except on the west coast where it can reach Zone 10. Seed production begins around the fourth decade, and lifespan can reach 300 years in its native range; introduced trees in the British Isles and North America live much shorter. As it ages, the crown thins and lower branches die. In the northern US and Canada, it is considered invasive in some areas, but not in Zone 6 and above, where seed germination is low in hot, humid summers. It tolerates acidic soils but not dry or deficient ones. From 1928 to the 1960s, it was planted on surface mine spoils in Indiana.

Several ornamental cultivars exist, including 'Barrya', 'Capitata', 'Decumbens', 'Dumosa', 'Clanbrassiliana', 'Gregoryana', 'Inversa', 'Microsperma', 'Nidiformis', 'Ohlendorffii', 'Repens', 'Tabuliformis', 'Maxwellii', 'Virgata', and 'Inversa'.