Wild garlic usually has a more slender rigid flowering stem with a white, greenish and sometimes pinkish flowering seed head. Wild garlic also rewards you by leaving a strong offensive odor on your hands if you handle it.
Wild onion is often more lush and sappy with purplish colored flowers. The odor it leaves is less offensive.
My photo here shows the flowering stem and seed head of wild garlic after the plant has already flowered and the tiny new aerial bulbs are visible. In this head are probably 90 or more new bulbs. The numerous green hairlike appendages are not new plants already growing as they may seem. They are merely end extensions of a thin protective skin around each new aerial bulb. When the stem dies in late June or July the small bulbs will drop to the ground, where some will take root. Wild garlic also propagates from new bulb generation underground around the white parent bulb.
Wild garlic is not good to eat. Your dog may get sick if it eats wild garlic.
Through the Woods is a weekly nature photo column by Aaron Horrell. Find this column at semissourian.com to order a reprint of the photo. Find more work by him at the Painted Wren Gallery.