Cucumber

A 95%-water vegetable

Cucumber is among the most water-rich foods in the produce aisle — about 95% water by weight. That’s part of why it’s so refreshing in hot weather, and part of why it loses crunch quickly: as it ages, water diffuses out and the vegetable goes flaccid. A firm cucumber should feel heavy for its size.

Pickling vs. slicing varieties

Pickling cucumbers (like the Kirby) have thinner skin, less water content, and tighter flesh — they hold up to brining without getting mushy. Slicing cucumbers are bred longer and meatier. The dilly pickle on a deli plate started life as a pickling cucumber; the slicer in your salad started as a slicing one.

A botanical fruit, a culinary vegetable

Like tomatoes, eggplants, and peppers, cucumbers are botanically fruits — specifically pepos, a kind of berry with a rind. We call them vegetables because we use them in savory contexts, not desserts.

Cooling, in fact

The mild scent and high water content do measurably cool the inside of a cucumber several degrees below ambient temperature, especially in shaded outdoor produce. That’s the literal source of the saying “cool as a cucumber.”

Burpless varieties

Some people experience burping or stomach discomfort from cucumber, attributed to a bitter compound called cucurbitacin concentrated in the skin and stem end. Modern cultivars marketed as “burpless” or “Beit Alpha” types are bred for very low cucurbitacin levels.