Oregano

Filed Under: Culinary Herbs, Fragrant Herbs, Herbs for Bees, Birds & Butterflies, Medicinal Herbs, Ornamental Herbs, Xeriscape Herbs

Origanum vulgare L.

Every American who eats Italian or Greek cuisine knows what oregano smells and tastes like. But dip into the gardening books and you quickly become aware that many different plants are called “oregano,” and that not all of them possess the hot, stimulating flavor and aroma we value in this herb.

Botanically, oregano falls into the genus Origanum, native from the Mediterranean to East Asia, a member of the ubiquitous Deadnettle Family (Lamiaceae). There are at present count 20 to 50 species in the genus, depending on what source you consult, all aromatic subshrubs or perennial herbs.

Most spring from a creeping rhizome, and all possess square stems, more or less oval leaves, and whorls of two-lipped flowers with conspicuous bracts, carried in spikes. The leaves of most species are downy, and range in color from chartreuse to bright green to dark green, blue-green, grey-green, green flushed burgundy, and green tipped gold. The flower-bracts, which in some species are showier than the flowers themselves, are sometimes tinged purplish, too, and the flowers range from white through pale pink to pink or mauve. Some are hardy to Zone 5; many, especially the species native to the Near and Middle East, are hardy from Zones 8 or 9-11.

“Origanum” comes from Greek words meaning “joy of the mountain,” presumably a reference to the ornamental inflorescences of some of the wild species, but as Tom Stobart points out, in Greece “there are no less than ten different wild species of [Origanum], known commonly under the name of rigani” (italics ours).

Oregano-scented plants called oregano that fall into families other than Origanum include:

  • Cuban Oregano (Plectranthus amboinicus)
  • Dominican Oregano (Lippia micromera)
  • Mexican Oregano (Lippia graveolens), see “All About Mexican Oregano”
  • Mexican Oregano (Poliomintha longiflora)
  • Puerto Rican Oregano (Plectranthus cv.)

All are used for cooking in their native countries.

VARIETIES OF “TRUE” OREGANO

Origanum vulgare (Common Oregano; Garden Oregano): The oregano everybody thinks they mean when they say “oregano.” In the European wild, a woody, rhizomatous, branching, strongly scented perennial herb to 3′ tall, with rounded, smooth-edged to slightly toothed leaves to 1.6″ long, dotted with oil glands on their undersides. The purple flowers, which are highly attractive to butterflies, are borne in late summer and autumn in a loose panicle or rounded head; the flower bracts are violet-purple or green. Zones 5-9.

Called by similar names around the world:

BRITISH: wild marjoram (grows wild in Britain on chalk downs and limestone)
FRENCH: l’origan
GERMAN: Oregano
ITALIAN: origano
SPANISH: oregano

Varieties include:

  • Origanum vulgare ‘Acorn Bank’ (Acorn Bank Oregano): To 18″ tall, with oval, pointed, “golden yellow” leaves and tiny pink summer flowers.
  • Origanum vulgare ‘Album’: 10″ tall and bushy, with light green leaves and white blossoms.
  • Origanum vulgare ‘Aureum’: See listing under Origanum vulgare ssp. vulgare.
  • Origanum vulgare ‘Aureum Crispum’: See listing under Origanum vulgare ssp. vulgare.
  • Origanum vulgare ‘Compactum’: Makes a 6″ tall cushion of small, round, dark green leaves and profuse summer clusters of tiny, violet-tinged, pink blossoms. Highly attractive to butterflies.
  • Origanum vulgare ‘Compactum Nanum’: To 4″ tall, with dark green leaves that turn purplish in winter and lilac flowers.
  • Origanum vulgare ‘Gold Tip’ (Gold Tip Oregano): To 18″ tall. The green leaves are aromatic and tipped with gold. Small pink flowers in summer.
  • Origanum vulgare ‘Heiderose’: Bushy and upright, to 16″ tall, with pink blossoms.
  • Origanum vulgare ‘Heideturum’: To 20″ tall, with light pink blossoms.
  • Origanum vulgare ‘Jim Best’: See listing under Origanum vulgare ssp. vulgare.
  • Origanum vulgare ‘Nanum’: To 8″ tall, with purple blossoms.
  • Origanum vulgare ‘Polyphant’: To 18″ tall. Another variegated oregano, this one with cream and green leaves and small pink summer flowers in clusters.
  • Origanum vulgare ‘Roseum’: Like the type, but with pink blossoms.
  • Origanum vulgare ‘Santa Cruz’: Another nonculinary type, with a nice oregano smell but little or no flavor. Said to be hardy only from Zones 8-11.
  • Origanum vulgare ssp. gracile: Native to East Anatolia, a region located in the western two-thirds of Asian Turkey. Defining characteristics: (1) Its leaves and calyxes are usually dotted with oil glands; (2) its leaves and green flower-bracts are more or less hairless; and (3) its slender-calyxed flowers are usually held in slender-stemmed, drooping spikes.
  • Origanum vulgare ssp. hirtum: Often listed as O. vulgare ‘Hirtum’, and listed as ‘Rigani’ in one source. DeBaggio’s calls this Greek Mountain Oregano. Native to Greece, Turkey, and the Aegean Islands. Differs from the type in that its leaves and calyxes are usually dotted with oil glands. In addition, its stems, leaves, and calyxes are densely hairy (though Jekka’s claims they are only “slightly” hairy), and the flower-bracts are hairy and green. The flower spikes are short and compact, with short branches; the white blossoms are carried in July and August. The leaves are said to be large, aromatic, and dark green, with an assertive flavor. “When chewed alone,” says DeBaggio’s, “[they] make the tongue tingle.” As we have seen, calling this variety rigani is something of a misnomer, since the Greeks themselves call lots of varieties by that name.
  • Origanum vulgare ssp. viride: Native to North and Central Turkey. Differs from the type in that (1) its leaves and calyxes are not usually dotted with oil glands; (2) its stems and leaves are covered with diffuse, soft, slender hairs; and (3) its green (occasionally purple-tinged) flower-bracts are often covered with minute hairs. The flowers are white or pale pink.
  • Origanum vulgare ssp. vulgare: To 18″ tall, differing from the type in that (a) its leaves and calyxes usually lack the dotted oil glands; (b) its stems and leaves are covered with soft, diffuse, slender hairs; (c) its flower-bracts are partly purple and often hairless or nearly so; and (d) its flowers are pink. Native to the Mediterranean and east to Southern China. O. vulgare ssp. vulgare ‘Aureum’ (Golden Creeping Oregano): Listed by DeBaggio’s, which says that it is a nonculinary cultivar of O. vulgare ssp. vulgare, though Jekka’s says it is useful in cooking. Yellow-green foliage on a fast-spreading plant. Occasionally puts up 12″ spikes of pink flowers. O. vulgare ssp. vulgare ‘Aureum Crispum’ (Golden Curly Oregano): DeBaggio’s says this is a nonculinary cultivar of O. vulgare ssp. vulgare, though Jekka’s says it is useful in cooking. Crinkled, aromatic, oval, golden green foliage. Pink summer flowers. O. vulgare ssp. vulgare ‘Dr. Ietswaart’: Like the preceding, with crinkled golden foliage. O. vulgare ssp. vulgare ‘Jim Best’ (Variegated Golden Marjoram ): DeBaggio’s says this is a nonculinary cultivar of O. vulgare ssp. vulgare. Green leaves streaked gold. Can take full sun but no foot traffic.
  • Origanum vulgare ‘Thumble’s Variety’: To 14″ tall, with large, pale yellow leaves maturing to yellow-green, and soft white blossoms.
  • Origanum vulgare ‘Tracy’s Yellow’: A vigorous gold-leaved cultivar.

OTHER OREGANO SPECIES

Hop marjoram (Origanum dictamnus)

Origanum dictamnus (Cretan Oregano; Dittany of Crete; Hop Marjoram): 6-12″ tall. Dwarf shrub native to the island of Crete, bearing prominently veined, oval to round, woolly white leaves and attractive, lolling panicles thickly whorled with tiny white flowers rising from beautiful, rose-purple bracts that resemble those of the hops plant (Humulus lupulus). Makes a nice drought-tolerant edging for beds, paths, and containers; overwinters on dry, well-drained, sunny soils in much of the Southwest U.S.A. Zones 7-11. Mostly medicinal uses, but sometimes used in cooking, too. This species is known in Crete variously as dictamo, ditamo, erontas, stomatochorto, and malliaro-chorto.

Origanum laevigatum: Hairless stems to 28″ tall, with oval leaves approaching leathery in texture, and purple blossom clusters in spring, summer, and early fall. Native to Turkey and Cypress. Zones 8?-10. There are a number of named cultivars.

  • O. laevigatum ‘Herrenhausen’: To 18″ tall, with purple-flushed juvenile shoots and leaves and pale lilac flowers in large clusters. The leaves flush purple again in winter.
  • O. laevigatum ‘Hopleys’ gets 30″ tall and bears large flowers of a strong pink color, protected by large bracts.

Origanum majorana (Sweet Marjoram, Knotted Marjoram): See “All About Sweet Marjoram” elsewhere on this site.

Origanum majoricum (Hybrid Oregano): There are or four hybrids listed under this botanic monicker, usually as Origanum x majoricum, all of which vie in the trade for the title of True Culinary Oregano. What Griffths’ Index of Garden Plants calls Origanum majoricum (note the lack of the “x” hybrid symbol) is a furry sterile perennial to 24″ tall, with 1″ long, narrow to oval leaves and pink flowers bracts over half their length, all held at the tips of their panicles. Native to Southwest Europe, where Griffiths says it is probably a natural stable cross of Origanum vulgare and Origanum majorana ssp. virens. This seems to be the plant that DeBaggio’s calls “Italian Oregano” and describes as an upright, nonspreading, green-leaved clump-former redolent with a sweet scent and hot stimulating, true oregano flavor. But there are others in the trade:

  • Origanum x majoricum ‘Culinary’ and Origanum x majoricum ‘Italian’: Both described as growing to 14″ tall, with white flowers.
  • Origanum x majoricum ‘Sicilian’: To 8″ tall, with white flowers.

Whether or not these four represent distinct cultivated forms of the same hybrid described by Griffiths is anybody’s guess.

Origanum microphyllum: Mediterranean native to 20″ tall, with oval, furry leaves to only about 1/3″ long. The summer flowers are tiny, too, held at the ends of drooping panicles; the blooms are protected by spatula-shaped bracts.

Origanum onites (Pot Marjoram): Tender mound-forming Mediterranean shrublet to about 2′ tall, with red stems described by Griffiths as furry and “warty”; oval, bright green, hairy leaves, sometimes heart-shaped at their bases; and clusters of small mauve or white summer blossoms appearing in late summer. Another source describes under this botanic monicker a plant with “pink, purple” flowers, but considering the prolificity with which oreganos cross I wouldn’t be surprised if we stumbled across one with blossoms marked with the words “EAT ME” in bold variegation. DeBaggio’s calls the aroma of this species incomparable, “strong but nuanced” but warns that it has “almost no heat when chewed.” Almost no flavor, either, in my experience.

Pretty, though, and drought tolerant, and a recent Italian study showed that adding up to 50 grams of pot marjoram leaves to each kilogram of feed increased the fertility and egg-productivity of quails being raised for their eggs by the food industry. The researchers recommended that other poultry egg raisers try the experiment, too, but warned that their tests showed that exceeding the rate specified above actually decreased the quails’ fertility. The original plant, claims DeBaggio’s, was brought to the U.S.A. “from a Greek island and was distributed by the National Arboretum.”Zones 8-11. O. onites ‘Kaliteri’: Praised by DeBaggio’s as “one great oregano, as any Greek will confirm.” Grey-green, “velvety” leaves containing “plenty of subtleties, but can still pack a punch.” Clumping habit; slow to flower, and said to make a good container specimen. I do not know its effect on quail egg production.

Origanum rotundifolium: Native to Armenia, the Republic of Georgia, and Turkey. To 1′ tall, spreading by rootstock, with furry stems and 1″ long, half-circular to heart-shaped, stem-clasping, blue-grey leaves. The tiny, white to pale pink flowers are held in late summer and early fall, in nodding, hops-like clusters; they are protected by showy, bright, pale green, kidney-shaped bracts tinged purple-pink. Zones 8-10. In German this species is known as Rundbl├Ąttrige Dost.

Origanum syriacum var. bevanii: A subshrub native to Cyprus and Turkey, growing to 3′ tall, with furry stems and oval, 1.4″ long leaves. The flowers are held in panicles in late spring and early summer, and are protected by “obovate” bracts, which means the bracts are oval, but that their narrower, pointy end is near the stem rather than the other way around.

COOKING WITH OREGANO

Oregano is usually used dried with bean, cheese, eggplant, fish, meat, shellfish, tomato, and zucchini dishes.

GROWING OREGANO

Grown in cold wet climates, it has a green taste, not very peppery; grown under hot dry conditions it develops its hot flavor

riganum onites (Pot Marjoram; Rigani):

Prefers a good light soil and sun but .. easy to grow. COOKING: Can be used to some extent for the same purposes as sweet marjoram esp. in the more strongly flavoured dishes such as with onion, wine, and garlic, where the delicate perfume of sweet m. would be largely lost.
Origanum heraclesticum (Winter Marjoram): Sometimes cultivated in gardens.
Origanum smyrnaicum:
Origanum paniflorum:
COOKING: Rigani are used with grilled meats and other Greek dishes.

Origanum dictamnus (Cretan dittany; dictamo, ditamo, erontas, stomatochorto, malliaro-chorto): Used mainly medicinally, sometimes as food flavoring.

SOURCES FOR THIS ARTICLE

  • Cetingul, I., Bayram, I., Yardimci, M., Sahin, E., Sengor, E., Akkaya, A., and Uyarlar, C., “Effects of oregano (Oregano [sic] Onites) on performance, hatchability and egg quality parameters of laying quails (Coturnix coturnix japonica).” The Italian Journal of Animal Science, Vol. 8, No. 3, 2009.
  • Skoula, M. and Harborne, J. “The taxonomy and chemistry of Origanum.” In Kintzios, Spiridon E., Oregano: The Genera Origanum and Lippia (Tylor & Francis, 2002).
  • Stobart, Tom. Herbs, Spices and Flavourings. (Harmondsworth, England: Penguin Books, 1977; ISBN 0-14046-261-9.)