If you mean to eat, then the named varieties are all one species (Asparagus officinalis).

They all have the same hardiness, its more to do with having good friable (crumbly) soil that is well drained and well fed for success. Cito is a good clone though Thompson & Morgan do a good strain that produces good crops from seed after three years and of course you get loads of plants too!

Hmmm...I've never tried it. They used to have a cracking Asparagus bed at the old Dundee Demonstration Garden, but now it's moved. Wonder if they are still growing asparagus? I seem to think it likes a lot of sunshine..is that right? If so, it looks like the main challenge for you is to find the right spot in your plot and get the soil really good!