Are there different types of amazon swords that grow to be different sizes? I have an amazon sword that came in a tube from Petco. It's been in my tank for almost a year (it was first in a 5 gal and now it's in a 10 gal), but it's only about 5 inches tall.
Then when I was setting up my 55 gallon, I bought some plants at an lfs and I saw the HUGEST amazon sword I've ever seen, so I bought it. The leaves go to the top of my tank, sticking up out of the water a bit, and that tank is 21 inches high! What makes one amazon sword grow to be only 5 inches, and another to over 21 inches?