As of July 2015, the FDA website has nutrition charts for vegetables that include protein information. The charts cover the 20 most frequently consumed raw vegetables.
FDA's site offers downloadable and printable PDF vegetable posters in small, medium, large and extra large sizes. In addition, a text version is accessible. Posters indicate the amount of protein per serving based on raw, edible weight portions of vegetables.
For example, seven radishes have no protein, while one 7-inch long carrot has 1 gram. One medium stalk of broccoli has 4 grams of protein. In addition to protein, the charts display values for calories, fats, carbohydrates, vitamins and minerals.