Will Russian kale, B. napas var. pabularia, cross with B. oleracea?
I don't think they will, but I need to be sure. The broccoli blooms flushed before the kale, but in a sneaky manner keeps putting out a bloom or two. It's getting tedious keeping them pinched back, saving seeds from both and don't want them crossed.
Russian kale, Siberian kale (B. napus) are not true kales. different species so chances of a cross are virtually nil. On the other hand broccoli will cross with all the true kales ( B. oleracea. With Russian or Siberian kale you have to watch out for turnips, rutabagas, rape and other B. napus. They will cross.