i think they would look much better with stems

I'd use fusible applique to add stems and I would make the leaves turn all different directions. Then it would look like fallen leaves.

I think they are very pretty. I would not add a stem. It leaves more interpretation to the viewer.

I do agree that they look beautiful as they are, but if you want stems I think Tartans idea would look great!

Should I put sashing between the blocks? all those seams are getting bulky together.

I personally like it just the way you have done it.

I just made three (3) utility quilts with the maple leaf pattern and I think your leaves need a stem. A stem would fill the hole where a stem should be. The pattern I used had a straight strip (3/4 inch wide cut) in the bottom left corner, where you have a half square triangle. You take a background square and cut it on the diagonal (from one corner to the opposite corner), place the strip between the two triangles and stitch a 1/4 inch seam and viola, you have a stem.

Leave as is and add stems and leave out the corner triangle next time.

I like this pattern it's like the Bear paw

You could even embroider a stem...if you want a thicker one, you could do a "couched" thicker thread...or machine satin stitch as wide as you can.