Low-Carb Vegetables
This list is roughly arranged from lowest to highest carbohydrate counts, but all are non-starchy and generally low in carbohydrates. Exact carb count depends on serving size. Remember when counting carbs in vegetables that the fiber is not counted, and can be subtracted from the total. For more information about each vegetable, including carbs, calories, glycemic index, and recipes, click on the vegetables that have a link.

    Sprouts (bean, alfalfa, etc.)
    Greens – lettuce, spinach, chard, etc.
    Hearty Greens - collards, mustard greens, kale, etc.
    Radicchio and endive count as greens
    Herbs - parsley, cilantro, basil, rosemary, thyme, etc.
    Bok Choy
    Bamboo Shoots
    Celery
    Radishes
    Sea Vegetables (Nori, etc)
    Mushrooms
    Cabbage (or sauerkraut)
    Jicama
    Avocado
    Asparagus
    Okra
    Cucumbers (or pickles without added sugars)
    Green Beans and Wax Beans
    Fennel
    Cauliflower
    Broccoli
    Peppers
        Green Bell Peppers
        Red Bell Peppers
        Jalapeno Peppers
    Summer Squash
    Zuchinni
    Brussels Sprouts
    Scallions or green onions
    Snow Peas/Snap Peas/Pea Pods
    Tomatoes
    Eggplant
    Tomatillos
    Artichokes
    Turnips
    Pumpkin
    Rutabagas
    Spaghetti Squash
    Celery Root (Celeriac)
    Carrots
    Onions
    Leeks

Starchy (High Carb) Vegetables
The main vegetables to be avoided when reducing carbohydrates are the starchier and sweeter vegetables:

    Carrots (some diets flag carrots as a problem, though they are lower in carbs than others in this group)
    Beets
    Peas
    Winter Squashes, such as acorn and butternut
    Water Chestnuts
    Parsnips
    Potatoes in all forms
    Sweet Potatoes
    Corn
    Plantains


source: http://lowcarbdiets.about.com/od/whattoeat/a/whatveg.htm