Hop clover and black medic are very difficult to distinguish from each other. They both have very similar leaves, 3 leaves that look like those of the white clover. Their flowers look like those of white clover, only much smaller, and yellow. Both species can grow up to 1-2 feet tall. So with all that information, lets look at a few easy ways to tell them apart.
Black medic and hop clover are difficult to distinguish from each other. There are two ways I use to tell them apart. Black medic has a "point" at the end of each leaflet. Hop clover has a smother tip. Black medic has a longer center leaflet, surrounded by two shorter leaflets. Hop clover's leaflets are around the same size.
Not only do they look like each other, but they also look similar to many other Ohio plants (yellow wood sorrel, red clover, white clover). Yellow wood sorrel has heart-shaped leaves, while black medic and hop clover have oval leaves. Red clover has dark check marks on its leaves, its leaves also being larger than those of hop clover and black medic. White clover sometimes has white blotches on its leaves. The easiest ways for me to tell white clover from black medic and hop clover are the white flower of white clover, and the leaflets of white clover have petioles similar in length.