You are right ChrisE.
I have some seeds from one example of 11a that are germinating now! It just takes longer to reach the flowering stage.
More than one species uses that name which is why I'm not generally fond of common names.
It depends on which genus you are talking about (mine actually make bulbs) but yes I agree, the C genus which I think the setter is referring to makes corms.
As usual (probably I'm better at guessing purely from letters than parsing), a small answer is the one giving trouble:
6d Heard Stand 11 is empty
_ A _ E
Any hints would be welcome