Origanum

Origanum, or oregano, is a genus of subshrubs and herbaceous perennials in the Lamiaceae or mint family that are grown primarily as ornamentals or culinary herbs. This genus has 45 species, 6 subspecies, and 3 varieties. Oregano may grow in bushy mounds, prostrate, or erect. The plants may measure 6 inches to 3 feet in height and 1 to 2 feet in width. The leaves are aromatic, small oval to round, and either smooth or hairy. The blooms may be white, pink, or purple and appear in small 1-inch spikes, panicles, or corymb. The fruit is small, ovoid, brown nutlet. The different species can vary in flavor, aroma, size, and color.

Oregano is native to Europe, Central Asia, the Mediterranean, and North Africa. It was introduced to the United States after World War II. Soldiers upon their return home to the United States reported how much they enjoyed the taste of oregano on pizza while in Italy. The demand for oregano has grown significantly.  

The genus name, Origanum, is derived from the Greek words, oros meaning "mountain" and gamos meaning "beauty." The plant is referred to as the "beauty of the mountain" because of its physical appearance and native habitats. Typically, the common name of most of the species or varieties describes that particular plant's flavor.

The oregano prefers full sun and needs well-drained to dry soil that is neutral or alkaline in pH. They are intolerant to acidic soils, poorly drained soils, and hot humid conditions. Oregano is drought, deer, poor soil, and erosion tolerant. They may be propagated by seeds, cuttings, or division. Bees and butterflies are attracted to their blooms.

There are many different types of oregano with different flavor profiles. Culinary uses of oregano include flavoring tomato sauces, egg dishes, soups, stews, dips, vinegar, vegetable dishes, and pizza. Medicinally, oregano has been used as an antiseptic and expectorant. As aromatherapy, it has been used to relieve respiratory congestion.

Plants from the genus Oregano may be used in herb gardens, cottage gardens, and rock gardens. They may serve as a groundcover, borders, or container plant.

Some of the species include:

• Origanum dictamnus (Dittany of Crete):  dwarf, evergreen, gray-white leaves, tiny pink flowers, ornamental
• Origanum laevigatum:  perennial, ornamental, purple-pink flowers, ornamental
• Origanum majorana (Sweet marjoram):  perennial evergreen subshrub with tiny pink or white flowers, culinary herb
• Origanum x majoricum (Italian Oregano):  perennial with white flowers, culinary herb 
• Origanum vulgare (Oregano or Wild Marjoram):  perennial with purplish-pink flowers, culinary herb

Quick ID Hints:

• stems may woody or non-woody
• leaves are rounded, cordate, or oval, opposite, hairy or non-hairy, entire or dentate margins, up to 1.5 inches long
• the color of the leaves is dependent on the species or cultivar--green, gray, or yellow
• blooms may be white, pink, or purple depending on the variety or cultivar, usually 5-lobed, maybe in panicles, spikes, or corymb
• fruit is an ovoid, brown nutlet

Insects, Diseases, and Other Plant Problems: Oregano usually has no serious insect or disease problems. Aphids, leaf miners, and spider mites may be found.  In wet or poorly drained soils, root rot or stem rot may occur. Monitor for fungal diseases and protect the plant from excessive winter moisture.

VIDEO created by Andy Pulte for “Landscape Plant Identification, Taxonomy and Morphology” a plant identification course offered by the Department of Plant Sciences, University of Tennessee.