So you think all mint is the same? It's not you know. What you have in your garden is likely SPEARMINT. What you see in stores and in culinary is likely PEPPERMINT. There are several cultivars and variants in the mint family - but PEPPERMINT and SPEARMINT are the two most common in cooking.
SPEARMINT (Mentha spicata) is the natural occurring cultivar and is native to Europe and Asia. It grows well in almost all temperate climates. Spearmint is a rhizomatous plant, sending roots underground and sprouting up new plants every few inches. The plant has hairless to hairy stems and foliage, with long serrated leaves. The stem is square-shaped, a hallmark of the mint family of herbs. The SPEARMINT plant will produce pink or white flowers on slender spikes.
PEPPERMINT (Mentha balsamea) is actually a hybrid. It is the result of a cross between Spearmint and Water-mint (Mentha aquatica). Peppermint is indigenous to Europe and the Middle East, grows well in most climates and is widely spread throughout the world. Peppermint has the typical square stems, slightly fuzzy, with the leaves a bit longer than the Spearmint cousin, much more coarsely toothed, with an acute apex. The flowers are purple and produced in whorls around the stem forming blunt spikes. Peppermint will have a reddish hue along the stems and veins of the leaves.
In cooking, SPEARMINT has less menthol, and therefore used in more savory dishes. Peppermint has an enormous amount of menthol, sometimes overpoweringly so. It is typically used when the main focus is the mint (menthol) flavor itself is desired.
An example of SPEARMINT use is in Greek cuisine. Pairing with yogurt or feta cheese is common, as is the use of Spearmint with lamb dishes. Many cuisines use Spearmint as a cooling effect and to add a slight surprising sweetness.
PEPPERMINT is generally used in candies such as peppermint sticks, drinks like the Mojito, as well as a flavoring in ice cream and other dishes where the primary focus is the cooling menthol.