Triploid hybrids 5. vulgaris L.×S. squalidus L. were synthesized, frequently using a diverse array of radiate and non-radiate plants of S. vulgaris as the female parent. All hybrids have so far proved sterile when selfed. By backcrossing one hybrid (S. vulgaris L. var. vulgaris×S. squalidus L.) to the female parent, and then selfing the products, several fertile radiate individuals were formed that were tetraploid and resembled S. vulgaris L. var. hibernicus Syme. The implication of these results for the possibility of introgression occurring between S. vulgaris and S. squalidus in the wild is discussed.