Spruces can be distinguished from other genera of the family Pinaceae by their needles (leaves), which are four-sided and attached singly to small persistent peg-like structures (pulvini or sterigmata[2]) on the branches, and by their cones (without any protruding bracts), which hang downwards after they are pollinated.

In the mountains of Dalarna, Sweden, scientists have found a Norway spruce, nicknamed Old Tjikko, which by reproducing through layering, has reached an age of 9,550 years and is claimed to be the world's oldest known living tree.

If, for instance, white spruce grown at container nurseries in southwestern British Columbia are not given an extended photoperiod, leader growth ceases early in the first growing season, and seedlings do not reach the minimum height specifications.

[12][13] But, if an extended photoperiod is provided for Sitka spruce, seedlings become unacceptably tall by the end of the first growing season.

[14] Species classification of seedlots collected in areas where hybridization of white and Sitka spruces has been reported has depended on (i) easily measured cone scale characters of seed trees, especially free scale length, (ii) visual judgements of morphological characters, e.g., growth rhythm, shoot and root weight, and needle serration, or (iii) some combination of (i) and (ii) (Yeh and Arnott 1986).

[14] Useful to a degree, these classification procedures have important limitations; genetic composition of the seeds produced by a stand is determined by both the seed trees and the pollen parents, and species classification of hybrid seedlots and estimates of their level of introgression on the basis of seed-tree characteristics can be unreliable when hybrid seedlots vary in their introgressiveness in consequence of spatial and temporal variations in contributions from the pollen parent (Yeh and Arnott 1986).

"Establishment" is a subjective concept based on the idea that once a seedling has successfully reached a certain size, not much is likely to prevent its further development.

[19][20] A 2006 study found that P. breweriana had a basal position, followed by P. sitchensis,[19] and the other species were further divided into three clades, suggesting that Picea originated in North America.

[21] P. sitchensis (Bongard) Carrière P. breweriana Watson P. likiangensis (Franchet) Pritzel P. farreri Page & Rushforth P. spinulosa (Griffith) Henry P. schrenkiana Fischer & Meyer P. smithiana (Wallich) Boiss.

& Zuccarini) Carrière P. rubens Sargent P. mariana (Miller) Britton, Sterns & Poggenburg P. omorika (Pančić) Purkyne P. obovata Ledeb.

[19] There are also a number of extinct species identified from fossil evidence: In the realm of spruce trees, the presence of Dendroctonus micans beetles significantly impacts their health and vitality.

These beetles, particularly the males, display territorial behavior, diligently defending areas that are attractive to females for mating.

By safeguarding these regions and providing suitable host trees, they create an environment conducive to egg-laying, thereby ensuring their reproductive success.

This territoriality is closely tied to male reproductive prowess and plays a crucial role in understanding the dynamics of beetle populations and their impact on the overall health of spruce trees.

Moreover, the home range of Dendroctonus micans varies based on the availability and density of host trees, with individual beetles dispersing across their habitat in search of optimal nesting sites.

[28] Twig blight damage to seedlings of white and red spruces in a nursery near Asheville, North Carolina, was reported by Graves (1914).

Sirococcus blight of spruces in nurseries show up randomly in seedlings to which the fungus was transmitted in infested seed.

Seed infestation has in turn been traced to the colonization of spruce cones by S. conigenus in forests of the western interior.

Infection develops readily if conidia are deposited on succulent plant parts that remain wet for at least 24 hours at 10 °C to 25 °C.

Wagg (1963)[33] attributed damage observed to the bark and cambium at ground level of small white spruce seedlings over several seasons to meadow voles.

[37] Repeated applications of half a million seeds/ha failed to produce the 750 trees/ha sought by Northwest Pulp and Power, Ltd., near Hinton, Alberta (Radvanyi 1972),[38] but no doubt left a lot of well-fed small mammals.

[48] Spruce wood is used for many purposes, ranging from general construction work and crates to highly specialised uses in wooden aircraft.

This replaces large amounts of vitamin C. Also, water is stored in a spruce's needles, providing an alternative means of hydration [clarification needed].

Spruce can be used as a preventive measure for scurvy in an environment where meat is the only prominent food source [clarification needed].

Native Americans in North America use the thin, pliable roots of some species for weaving baskets and for sewing together pieces of birch bark for canoes.