This symposium is the third in a series featuring the propaga- tion of higher plants through tissue culture. The first of these symposia, entitled "A Bridge Between Research and Application," was held at the University in 1978 and was published by the Technical Information Center, Department of Energy. The second symposium, on "Emerging Technologies and Strategies," was held in 1980 and pub- lished as a special issue of Environmental and Experimental Botany. One of the aims of these symposia was to examine the current state- of-the-art in tissue culture technology and to relate this state of technology to practical, applied, and commercial interests. Thus, the third of this series on development and variation focused on embryogenesis in culture: how to recognize it, factors which affect embryogenesis, use of embryogenic systems, etc.; and variability from culture. A special session on woody species again emphasized somatic embryogenesis as a means of rapid propagation. This volume emphasizes tissue culture of forest trees. All of these areas, we feel, are breakthrough areas in which significant progress is expected in the next few years.