Sophenensis x danfordiae (sxd) crosses are fertile. The first generation (F1) were "just blues", ranging from light blue to dark blue. As expected, the expression is opening up in the second generation (F2). In 2002 the number of F2s increased by 36, bringing the total to 57! They can be grouped into 7 basic categories: whites with blue markings; whites; yellow-blues; danfordiae-like; light blue-green; blue; and miscellaneous.
See the article 'A Whole New World' for more details.