Black spruce [Picea mariana (Mill.) B.S.P.], known by many alternate common names including bog spruce, swamp spruce, Canadian spruce, eastern spruce, and shortleaf black spruce (Viereck and Johnston, 1990; Alden, 1997), is one of the most common and important boreal species native to North America, especially in eastern Canada. Black spruce is one of about 40 species in the genus Picea of the family Pinaceae, all of which are found in cooler portions of the northern hemisphere (Farrar, 1995). Ten spruce species are native to North America (Weng and Jackson, 2000). There is no consensus among taxonomists regarding subdivision of the genus, but Picea is often described as having three sections (Eupicea, also known as Picea or Morinda; Castica; and Omorika), with black spruce generally placed among the Eupicea (Dallimore and Jackson, 1948; Alden, 1987). Mikkola (1969) suggested dividing the genus into only two sections, Abies and Omorika. Fowler (1983) recommended adopting Mikkola’s classification, but splitting the section Omorika into two subsections, Omorikoides and Glaucoides, and placing black spruce into the former subsection based upon species crossability. Other examples of taxonomic classification have also been proposed for the genus (e.g., see Weng and Jackson, 2000).