Oh right
I don't grow my crypts emersed so I don't know what the emersed growth of mine looks like. Might give it a go if we ever move to a new house so I have more room for tanks and stuff.
Just been doing a bit of research on google, and apparently C. willisii is a huge complex of all different sorts of variations and hybrids, which makes identification very confusing So there is no definate name for anything in the willisii complex, which is why it is normally labled as 'Cryptocoryne x willisii', the x meaning it is a cross/hybrid between diffeent species. So their are many different types of willsii all with various differences. I'm now not exactly sure about what 'lucens' is...
My 'willsii' has very long leaves and long leaf stalks, longer than photos of plants I've seen labled as 'lucens' or 'willisii x lucens'. It is still relitively small, although larger than plants labled as 'lucens'. Also the leaves have pointy ends and not roundish ends like plants labled as 'lucens'. It is also confined to a pot so it would probably grow much bigger if it was just planted in a bed of substrate and allowed to do whatever it wants.
This thread is pretty interesting -
http://www.aquaticplantcentral.com/forumapc/plant-id/60818-crypt-parva-vs-crypt-x-willisii.html