1. Smith, B. N., and Epstein, S., Plant Physiol., 47, 380 (1971); Tregunna, E. B., Smith, B. N., Berry, J. A., and Downton, W. J. S., Canad. J. Bot., 48, 1209 (1970).
2. Björkman, O., Nobs, M. A., Pearcy, R. W., and Berry, J. A., Carnegie Inst. Wash. Year Book, 68, 620; ibid., 69, 622 (1970, 1971).
3. Tateoka, T. J., Jap. Bot., 32, 275 (1957); Brown, W. V., Bot. Gaz., 119, 170 (1958); Prat, H., Bull. Soc. Bot. France, 107, 32 (1960); Stebbins, G. L., and Crampton, B., Recent Advances Bot., 133 (University of Toronto Press, 1961); Augier, P., Natura Mosana, 16, 1 (1963).
4. Downton, J., Berry, J., and Tregunna, E. B., Science, 163, 78 (1969); Krenzer, E. G., and Moss, D. N., Crop Sci., 9, 619 (1969).
5. Tateoka, T., Taxon, 18, 263 (1969).