Look at the foliage on this picture. Hyacinths are different from grape hyacinths, wood hyacinths, water hyacinths, and purple hyacinth beans. Sheesh, you think they'd have picked different common names for all these things.
http://images.google.com/imgre...
Scroll down and click on the image for Hyacinthus ‘Blue Jacket’ (hyacinth) .