Abstract Crosses between white spruce ( Picea glauca ), red spruce ( P. rubens ), blue spruce ( P. pungens ), and ( P. glauca x P. pungens ) from several seed and pollen parents were made during 1974-76. The seeds were grown for 6 months with the aid of continuous illumination and several characters were measured to verify the hybridity of the seedlings. Hybrids of rubens with glauca and ( glauca x pungens ) were verified on the basis of differences in needle color, number of needle serrations, and concentrations of 3-carene, limonene, and β -pinene in the cortical oleoresin. P. glauca x pungens hybrids were verified with more difficulty by a combination of needle curvature and 3-carene concentration. The backcrosses, ( glauca x pungens ) xglauca and ( glauca x pungens ) x pungens , were differentiated from each other by growth rate, needle curvature, and concentrations of 3-carene and β -pinene. For most traits, putative hybrids were intermediate to their parents. However, F 2 glauca x pungens hybrids were severely stunted, possibly owing to consanguinity of the parents. Forest Sci. 28:129-134.