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.

Like most tender greens, arugula is perishable and needs to be used within a few days of purchase. Look for crisp leaves without mushiness.

Red and green cabbage should have a firm, tight head and feel heavy for their size, with no black or soft spots. Savoy and Napa cabbage are generally a bit "looser".

Cardoons are sold in large bunches that look a lot like spiky, silvery celery. Stalks should be firm with no spongy or blackened spots.

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.

This includes radicchio, endive, frisee and escarole — bitter, leafy veggies that come in a rainbow of colors.

Look for endive with tight heads that feel heavy for their size. All endive varieties should be free of black or mushy spots, with very few (to no) brown or wilting leaves.

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.

When shopping for kale, stay clear of wilted or browning leaves. Leaves and stalks should be firm and dry instead of wilted and mushy.

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.

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

Mustard greens are peppery, leafy greens in the same family as broccoli and kale. Look for perky greens that are not wilted with no mushy or black spots.

Nopales are the leaves of the prickly pear cactus. Harvesting young pads makes for a much easier time removing spines, although some vendors sell them with the spines already removed.

When purchasing dried onions, avoid brown or mushy spots and choose onions that feel heavy for their size without any signs of sprouting.

Parsnips are a root vegetable that look like a pale carrot, usually a shade of pale yellow or ivory. Look for parsnips that are firm but not tough.

Quinces resemble a pear but are bumpy and round in the middle. It's common to find some nicks and bruises in its delicate skin but avoid fruit with dark brown or black mushy spots.

Radicchio is a bitter leafy vegetable. Radicchio di Chioggia, the most common variety, resembles a small red cabbage, but radicchio comes in a variety of other shapes. In all cases, it should be crisp and unwilted.

Most radishes are sold with the tops attached: look for vibrant greens and firm roots. Don't forget you can saute the tops or use them in pesto!

With its pine-like flavor, rosemary pairs well with roasted vegetables and grilled meats. Look for strong-smelling bunches and avoid withered leaves.

The rutabaga is a sweet root vegetable that looks a lot like a large turnip with pale yellow flesh. Rutabagas are often sold with a protective layer of wax that improves shelf life, so peel them before cooking.

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.

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.

Fresh thyme imparts a bright, almost lemony flavor to soups, roasts and other dishes. When buying thyme, leaves should be fresh, green and firmly attached to the stems. Thyme with lots of wilted leaves is less fresh.

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.

Winter squash is actually harvested in autumn before a hard frost and stored for later. Squash comes in many sizes and colors and may even have decorative warts. Avoid squash with visibly broken skin.