Is Sudex a brassica?
No, “Sudex” and “Sudax” are brand-name sorghum/sudangrass cross varieties. “Sudax” is owned by DeKalb, I think.
These are warm-season grasses commonly used for fast cover, green manure, etc.
Here’s a good quick summary of the cultural characteristics of Sudex:
http://www.ctahr.hawaii.edu/oc/freepubs/pdf/GreenManureCrops/sorghum-sudan.pdf
Brassicas are sometimes known as “mustards” when farmers are talking about seed-bearing brassicas. You no doubt eat a wide variety of brassicas:
Broccoli, cauliflower, turnips, swede/kale, brussel sprouts, cabbage, kolabri, etc.
The seed-bearing brassicas are various mustards, crambe, rape, canola (as a breed of rape), and have various levels of oil in their seeds. Mustards are known for being very hardy weeds where you don’t want them.
The leafy brassicas, the kale, swede, turnips, etc — those make fantastic quick-yielding grazing material.