To test intra-specific and interspecific out-crossing, all the seed was harvested from a plant of A. vulgaris, recessive for 2 Mendelian factors. It was adjacent to plants of A. vulgaris carrying the dominant factors and to A. skinneri with which it was fertile when artificially pollinated. The progeny test showed that out-crossing within the species produced at least 16% of the offspring but that effective out-crossing with A. skinneri had not occurred.