Elderberry plants are recognizable by their pointy green leaves and clusters of tiny purple berries. If you come across elderberry plants in the wild, you need to ensure that they are actually elderberries before you think about eating them. Water hemlock looks similar to elderberry plants, but it is extremely toxic. One of the main visible differences between elderberry and water hemlock is the pith, which is found along the center of the branches.
Cut a branch of the plant at an angle with a sharp knife or scissors. An angled cut is better, as it exposes more of the pith.
Look at the color of the pith. Elderberry pith has a white or very light grey color.
Examine the texture of the pith. Elderberry pith has a slightly bumpy, sponge-like texture.
Feel the pith. It should feel somewhat spongy, but still firm.