Spruces in the Arnold Arboretum

• Main Author: Richard Warren
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; Norway
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.510.604; http://arnoldia.arboretum.harvard.edu/pdf/articles/1134.pdf

The members of the genus Picea (the spruces) grow exclusively in the North Temperate Zone and stretch around the world in the higher latitudes. In North America they grow above the Arctic Circle to latitude 70 ° north and extend south into Mexico. In favorable climates they reach heights of 70 meters. Among conifers this range is matched in extent only by the genera Pinus (pines) and Juniperus (junipers). Although relatively sensitive to air pollution and drought, spruces tolerate shade better than most other conifers. Some members of the genus have no peers in their ability to stand extreme cold. The Arboretum’s mission to grow all woody plants hardy in our climate has been well fulfilled in the case of the spruces. The rep-resentatives of the 21 species now growing on the grounds demon-strate many interesting features. DESCRIPTION OF THE GENUS Picea belongs, under the gymnosperms, to the family Pinaceae, in which the plants are monoecious, with spirally arranged linear or needlelike leaves, two microsporangia on each microsporophyll, two ovules on each ovuliferous scale (to which the bract scale is not, or is only loosely, attached), and pollen grains with "wings. " The other members of the family are Abies (the firs), Cathaya (a recently de-Above ~ ArnoldArboretum pinetum xn wxnter The two tallest trees are Norway spruces. Photograph by R Warren Below Range of spruces in the world Shading indicates contiguous distribution, and dots show scattered occurrences. Map drawn by L. Mes-zoly after Schmzdt-Vogt (1977)