Worldwide, there are more than 7,500 known varieties, 100 of which are grown commercially in the US. They all differ in shape, size, color, texture, aroma and flavor.

Carrots come in all shades of purple, red, white, yellow and of course, orange. If they have the greens attached, look for feathery, perky leaves with no wilting, black spots or yellowing.

Also known as celeriac, this turnip-sized bulb grows underground. Look for a firm, apple-sized celery root with no soft or squishy spots.

Look for leaves that are dry and free of dark green goop. No yellowing or wilted leaves, which are signs of decay.

Fennel bulbs should be whitish-green, firm and heavy for their size, with no brown or mushy spots. If the feathery green fronds are still attached, they should have no signs of wilting or dryness.

Horseradish is a large and tapering root with a dark brown peel and creamy interior. Look for firm roots with no mushy or black spots.

Both the root and leafy greens of kohlrabi are edible. The bulb should be firm with no spongy bits and no visible brown spots.

This wild-foraged leafy green packs a nutritional punch with lots of protein, fiber, omega fatty acids and Vitamins A and C. Look for leaves that are perky.

Common leeks look like giant scallions and have a mild onion-y, sweet flavor. Look for leeks on the smaller side, 1-2" in stem diameter with very dark greens that have no yellowing or wilted spots.

There are many varieties of lettuce, from loose-leaf to those bought as a head. For all varieties, look for leaves that are intact and not wilting.

Used both in cooking and herbal medicine, mint should have perky stems and leaves with no black spots or wilted parts. Fresh mint should also be very aromatic.

There are several varieties of mushrooms and they can be purchased fresh or dried. Look for fresh mushrooms without slimy, moldy or black spots.

Oregano and marjoram are both available as fresh or dried herbs. To preserve freshness, store dried herbs in a cool, dry place and store fresh herbs in the refrigerator.

Parsley is available in both curly and flat-leaf varieties. For both, look for firm, perky leaves, firm stems and no wilting or yellowing of any kind.

Purslane has the most omega-3 fatty acids of any green vegetable. Its flavor is slightly tart and a bit lemony - perfect for summer salads.

Rapini, or broccoli rabe, looks like a leafier version of broccoli. Both the leaves and florets should be deep green without yellow spots.

With its distinctive smell, sage adds a savory note to many dishes. Look for sage that has perky, silvery green leaves and a strong smell, avoiding any withered or dry leaves.

Salsify is a slender woody root, with light brown or black skin and white flesh. White salsify is said to be similar to oysters in flavor.

Sorrel comes in both red and green varieties, but both resemble spinach. Sorrel has a sharp, tart, green apple taste that adds a tang to salads and cooked greens.

Although you can sprout many seeds, the two most common sprouted types are bean and alfalfa. Look for sprouts that are perky and smell fresh. Avoid any that smell off or that appear slimy or wilted.

Sometimes called Jerusalem artichokes, sunchokes are the roots of a native North American plant in the sunflower family. Look for roots that are firm to the touch, with no spongy or mushy areas.

Nutritional powerhouses, sweet potatoes come in an array of shapes and colors. Look for sweet potatoes without dark blemishes or soft, discolored areas.

Sweeter and milder than their larger counterparts, baby turnips are perfect for eating raw, roasting or tossing in salads. Turnips should be firm with tight skin. Avoid any that look wrinkled or withered.