Most things I have read have to do with height of plant.
This is from NH Hosta.
Size Categories:
Hosta sizes are based on their mature height.
Hostas Grown in the North
Miniature: Less then 8 inches tall
Small: 9-14 inches tall
Medium: 15-22 inches tall
Large: 23-29 inches tall
Giant: 30 inches and above
Hostas Grown in the South
Miniature: Less then 7 inches tall
Small: 8-11 inches tall
Medium: 12-18 inches tall
Large: 19-24 inches tall
Giant: 25 inches and above
The above size ranges reflect the fact that any specific hosta cultivar will generally grow a few inches taller in Northern climates as compared to Southern climates. The larger the hosta, the greater the spread between heights in the North and South.
And some also mention width.
http://www.plantsgalore.com/ho...
But have not found reference to leaf size.
