We investigated the areas of water penetration and the anatomical structures of hilar regions of permeable and impermeable seed coats of lima beans (Phaseolus lunatus L.). Results indicate that water can enter permeable seeds through the hilum, raphe, and micropyle. In impermeable seeds water cannot pass through any of these areas. Anatomical data confirm that there were no structural differences in the testae of permeable and impermeable seeds, but a noticeable difference was apparent in the hilar region. In permeable seeds the palisade layer did not connect evenly in the hilar canal. By contrast, the hilar canals of impermeable seeds had connected palisade layers that were uniformly coated with a cuticular layer. Micropylar openings were clearly visible in permeable seeds, but these openings were occluded and well covered with cuticle in impermeable seeds. Visible differences were evident in the raphe.
Received for publication July 15, 1970. This investigation is a portion of a thesis submitted by the senior author in partial fulfillment of the PhD degree in Plant Science, Utah State University. Contribution from the Department of Plant Science and Crops Research Division, Agricultural Research Service, U. S. Department of Agriculture, Utah Agricultural Experiment Station, Logan, Utah. Published with the approval of the Director of the Utah Agricultural Experiment Station as Journal Article No. 619.
Present address: Department Plant Sciences, Kasetsart University, Bangkok, Thailand.
The authors wish to express their sincere gratitude to the Rockefeller Foundation for financial support of the senior author during the course of this investigation.