Wild onion (A. validum or A. canadense) is a bulbous herb of the Amaryllis family and is a close relative of cultivated onion (Allium cepa L.). It has a distinct onion odor. It has slender grass-like leaves and reaches about 2 feet in height when flowers appear in late summer. Leaves are narrow, long, and with parallel edges arising from the small underground bulb.
Flowers, varying in color, depending on the species, from white to pink, appear at the top of a leafless stem and eventually become bulblets which drop to the ground and propagate.
It is thought that the name Chicago is derived from the smell of wild onions: "Indians, mainly Potawatomi, who were the most powerful tribe around the south end of Lake Michigan, hunted, traded furs, and occasionally camped in the area they called "Checagou," evidently referring to the garlic wild onion smell which permeated the air."
Bulb has reticulated (net like) membrane or covering.
Leaves occur from the base of the plant, and tend to be flat (not hollow).
Leaves are hollow, and tend to be formed higher on the stem (not where stem comes out of the ground).
Distinct garlic odor.
The plants are difficult to remove by hand and generally break off at the soil surface when trying to pull out by hand.
If you resort to herbicides, there are a few good options. Two non-selective postemergent herbicides that can be used are Roundup. These herbicides can be used as a post-directed spray, making sure to keep the spray off other plants. Selective herbicides for turfgrass include metsulfuron methyl (Manor®), imazaquin (Image), imazapic (Plateau), and 2,4-D. These herbicides can be used safely over-the-top on most turfgrasses. All of these herbicides appear to control wild onion. Be certain you read and understand the herbicide labels before applying any chemical.
TIP: When using these herbicides, it is best to use rubber gloves and dip a small scouring pad sponge int the herbicide and rub the sponge up the length of the plant. This causes minute scratches and allows the herbicide to penetrate the waxy layer.