All Leaves < 4 cm Long

The Naiads are often extremely difficult to tell apart, even for experts. It is especially difficult to tell Najas minor and Najas gracillima apart, as N. minor looks very much like N. gracillima when it is immature. If the leaves are strongly recurved, you can be fairly certain you have N. minor. If the leaves are straight and weekly toothed, it could be either species. Look at all the hints to make sure you’ve keyed this out correctly.
 

Toothed and Strongly Curved Leaves leaves are strongly re-curved (curved backwards), with many prominent teeth on each leaf.

Flattened Leaves with No Teeth leaves are flattened, with no visible teething

Flattened Leaves, Weakly Toothed leaves are straight, fine and weakly toothed