Yes, we can recognize the leaves without seeing them. It is possible by taking an impression of the leaf. To get an impression, we put a leaf under a white paper. Hold the pencil tip sideways and rub it on the portion of paper having leaf below. You get

To get an impression, we put a leaf under a white paper. Hold the pencil tip sideways and rub it on the portion of paper having leaf below. You get the impression of the leaf with some lines on it. These lines on the leaf are called veins.

1) The design made by veins of a leaf is called leaf venation.

2) If we get the net-like design on both sides of midrib, then the leaf has reticulate venation.

3) If we get lines parallel to each other, then the leaf has parallel venation.