– **Growth and Taxonomy of Spruce**
– Spruce seedlings are most vulnerable immediately following germination, with over half of seedling mortality occurring in the first growing season.
– Mortality rates decrease sharply after the first growing season.
– Growth is slow for several to many years, with establishment based on reaching a certain size.
– DNA analyses have shown that traditional classifications of spruce based on morphology are artificial.
– A 2006 study revealed that Picea originated in North America.
– The oldest record of spruce in the fossil record dates back to the Early Cretaceous.
– As of April 2022, there are 37 accepted species of spruce based on the grouping by Ran et al. (2006).
– Species range from 20 to 60m tall, with unique needles attached singly to branches and downward-hanging cones after pollination.
– **Classification and Hybridization of Spruce**
– Picea breweriana is a basal species, while Picea sitchensis is the largest, reaching up to 95m tall.
– Clade I includes species from northern and western North America.
– Picea engelmannii is significant in forestry, and Picea glauca hybridizes with P. abies.
– Morphological differentiation among spruce species and hybrids is challenging without cones.
– Species classification of seedlots is crucial for nursery regimens.
– Genetic composition of seeds is influenced by both seed trees and pollen parents.
– Accurate discernment of spruce hybrid seedlot composition is difficult due to various factors.
– **Ecology and Diseases Affecting Spruce**
– Various fungi species cause diseases like shoot blight, seedling mortality, twig blight, and cankers in spruces.
– Spruce trees are vulnerable to pests like eastern spruce budworm, spruce beetles, and horntails.
– Pest outbreaks can lead to extreme defoliation and damage to spruce forests.
– Control methods, including pesticides, are used to manage pest populations.
– Small mammals, squirrels, and rodents can also impact spruce trees through seed consumption and bark damage.
– **Uses of Spruce**
– Spruce wood is commonly used in construction, paper production, and specialized applications like wooden aircraft.
– Spruce essential oil finds applications in food and medicine.
– Spruce is cultivated for pulpwood production and is essential for soundboards in musical instruments.
– Spruce resin has historical uses in pitch production, and Native Americans used spruce roots for various purposes.
– Spruces are popular ornamental trees and are commonly used as Christmas trees.
– **Genome and Research Studies on Spruce**
– The nuclear, mitochondrial, and chloroplast genomes of British Columbia interior spruce have been sequenced.
– Various studies have been conducted on spruce hybridization, taxonomy, and ecology.
– Notable research includes studies on white spruce ecology, small mammals’ impact on regeneration, and pheromone communication in moths affecting spruce.
– Genome sequencing projects have focused on white spruce, including the assembly and annotation of organellar genomes.
A spruce is a tree of the genus Picea (/paɪˈsiː.ə/ py-SEE-ə), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. Picea is the sole genus in the subfamily Piceoideae. Spruces are large trees, from about 20 to 60 m (about 60–200 ft) tall when mature, and have whorled branches and conical form.
| Spruce Temporal range:
| |
|---|---|
| |
| Norway spruce (Picea abies) | |
Scientific classification 
| |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Gymnospermae |
| Division: | Pinophyta |
| Class: | Pinopsida |
| Order: | Pinales |
| Family: | Pinaceae |
| Subfamily: | Piceoideae Frankis |
| Genus: | Picea Mill. |
| Type species | |
| Picea abies | |
| Species | |
|
About 35; see text. | |
| Synonyms | |
| |
They can be distinguished from other members of the pine family by their needles (leaves), which are four-sided and attached singly to small persistent peg-like structures (pulvini or sterigmata) on the branches, and by their cones (without any protruding bracts), which hang downwards after they are pollinated. The needles are shed when 4–10 years old, leaving the branches rough with the retained pegs. In other similar genera, the branches are fairly smooth.
Spruce are used as food plants by the larvae of some Lepidoptera (moth and butterfly) species, such as the eastern spruce budworm. They are also used by the larvae of gall adelgids (Adelges species).
In the mountains of western 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.