Book Reviwed in this article: Petaloid Monocotyledons. Ed. by C. D. Brickell, D. F. Cutler and M. Gregory. The Oxford Encyclopedia of Trees of the World. Ed. by Bayard Hora. 11 × 8 1/2 in. Pp. 288 with 85 colour‐plates and over 280 coloured text‐figures. Oxford: Oxford University Press. 1981. Price £12.50. The Arctic and Antarctic: their division into geobotanical areas. By V. D. Aleks‐Androva. Translated by Doris Löve 21·4 × 13·4 cm. Pp. xiii + 247 with 23 text‐figures. Cambridge: Cambridge University Press. 1980. Price £15.00. Hormonal Regulation of Development I. Molecular Aspects of Plant Hormones. Encyclopedia of Plant Physiology, New Series, Volume 9. Ed. by J. Macmillan. 9 1/2 × 6 1/2in. Pp. xvii + 681 with 126 text‐figures. Berlin, Heidelberg, York: Springer‐Verlag. 1980. Price $134.60, reduced to $107.10 if purchased with volumes 10 and 11. The Biology of Botrytis. Ed. by J. R. Coley‐Smith, K. Veriioeff and W. R. Jarvis. 9 × 6 in. Pp. xiv + 318 with 1 plate and 68 text‐figures. London: Academic Press. 1980. Price £ 26.00, $62.50. Plant Growth Substances 1979, Proceedings of the 10th International Conference on Plant Growth Substances, Madison, Wisconsin, July 22–26, 1979. Ed. by F. Skoog. 91/2×61/2 in. Pp. xvi + 527 with 208 text‐figures and 59 tables. Berlin, Heidelberg and New York: Springer‐Verlag. 1980. DM98, U.S. $57.90. The Biology of Desmids. By A. J. Brook, Ed. by J. H. Burnett, H. G. Baker, H. Beevers and F. R. Whatley. 91/2 × 61/2 in. Pp. 276. Oxford: Blackwell Scientific Publications. 1981. Price £23.50. The Blue Light Syndrome. Ed. by H. Senger. 91/2 × 61/2 in. Pp. xvi + 665 with 432 text‐figures. Berlin, Heidelberg, New York: Springer‐Verlag. 1980. Price DM 98. Introduction to the Principles and Practice of Soil Science. By R. E. White. 9 × 8 in. Pp. 198. Oxford: Blackwell Scientific Publications Ltd. First published 1979. Water in Plants Bibliography, Volume 5,1979. By J. Pospisilova and J. Solarova.