Parsley: Curly vs. Flat-Leaf, Flavor Chemistry, Uses and Safety

Parsley gets written off as garnish, but it has a real flavor: green, fresh and slightly bitter, and that bitterness can sharpen other flavors the way a squeeze of lemon does. It’s the leaf of Petroselinum crispum, a biennial in the carrot family. The curly and flat-leaf types differ in their chemistry as well as their looks, and flat-leaf is the stronger flavored of the two. Don’t toss the stems, either. They carry more flavor than they get credit for.

At a glance

Measured values

13 figures, sourced

Measure	Value	Scope	Source
Essential oil	less than 0.5 %	Parsley, Britannica (plant part not specified)Sources differ: PROSEA gives lower figures for the fresh herb; the two may not describe the same plant part.	britannica.com
Essential oil	0.07–0.15 % of fresh herb	Curly types, PROSEA	uses.plantnet-project.org
Essential oil	0.04 % of fresh herb	Flat-leaved type, PROSEA	uses.plantnet-project.org
Essential oil	0.05 % of fresh herb	Turnip-rooted type, PROSEA	uses.plantnet-project.org
1,3,8-p-Menthatriene	about 20 % of leaf oil	German-grown flat-leaved and curly samples, PROSEA	uses.plantnet-project.org
Myristicin	about 32 % of leaf oil	German-grown curly sample, PROSEA	uses.plantnet-project.org
Myristicin	9.1 % of leaf oil	German-grown flat-leaved sample, PROSEA	uses.plantnet-project.org
Limonene	18 % of leaf oil	German-grown flat-leaved sample, PROSEA	uses.plantnet-project.org
Limonene	14 % of leaf oil	German-grown curly sample, PROSEA	uses.plantnet-project.org
Apiole	33.3 % of seed (fruit) oil	French flat-leaved sample, PROSEA	uses.plantnet-project.org
Myristicin	22.5 % of seed (fruit) oil	French flat-leaved sample, PROSEA	uses.plantnet-project.org
Myristicin	56 % of seed (fruit) oil	French curly sample, PROSEA	uses.plantnet-project.org
Ascorbic acid (vitamin C) Nutrient	122 mg per 100 g	Dried parsley, PROSEA composition table	uses.plantnet-project.org

Each figure is quoted as its source states it, with the samples or standard it applies to. Where sources differ, both are shown; nothing is averaged. All measured values

What parsley is

Parsley is a biennial or perennial of the temperate biome. As a biennial, it grows leaves in its first season. The compound leaves are deep green and tender, either flat or deeply frilled. There are three cultivated groups:

• Curly-leaved parsley has compact branches with curled leaf blades. Its fresh leaves are mostly used for garnishing and seasoning.
• Flat-leaved parsley, often sold as Italian parsley, has more open branches with flat leaf blades.
• Turnip-rooted parsley, also called Hamburg parsley, is grown for a large white root that’s parsnip-like and popular in Europe. PROSEA says these thick-rooted forms are recent, probably developed around 1500 AD in northern Germany.³

For the differences in the kitchen, see Italian parsley vs. curly parsley and flat-leaf vs. Italian parsley.

Flavor and aroma

Parsley tastes green and fresh with a light bitterness, and that bitterness can sharpen other flavors the way a squeeze of lemon does. The leaves are mildly aromatic. Parsley herb oil tastes warm but slightly burning and bitter, and flat-leaved parsley is stronger flavored than curly.

The compounds

Britannica puts parsley’s essential oil at less than 0.5% and names apiol as its main component.² PROSEA’s figures for the fresh herb are lower: about 0.07–0.15% oil in curly types, 0.04% in flat-leaved and 0.05% in turnip-rooted.³ The two references may not be describing the same plant part, so you get both.

The leaf oil differs by type. In PROSEA’s figures for German-grown samples, flat-leaved and curly parsley both had about 20% 1,3,8-p-menthatriene. But the curly type’s oil carried about 32% myristicin against 9.1% in flat-leaved, and limonene ran 18% in flat-leaved against 14% in curly. The seed (fruit) oil is a different product: PROSEA reports apiole (33.3%) and myristicin (22.5%) in a French flat-leaved sample and myristicin at 56% in a French curly sample.³

Origin and history

Kew gives parsley’s native range as northwest Africa and the Balkan Peninsula, listing Algeria, Greece, Morocco and the northwest Balkans.¹ Britannica just says Mediterranean lands.²

The name comes through Medieval Latin and Latin petroselinum from Greek petroselinon, “rock-parsley”, from petros (rock, stone) and selinon (celery). That’s where the “stone” in the name comes from. We found no source tying it to where the plant was first found growing.

Parsley is an old crop, well known in classical Greece and Rome, where the leaves flavored and garnished food. Plenty of stories about parsley’s past get passed around: Greek legends of it springing from a hero’s blood, Roman use on corpses, Charlemagne’s gardens, medieval sayings about germination. We couldn’t trace any of them to a source, so we’ve left them out.

Production and trade

We found no official production figure for parsley. PROSEA, in undated figures, reported that parsley accounts for over half the area planted with culinary herbs in the United Kingdom, and that more than 10,000 tonnes are eaten each year in 23 major US cities.³

How parsley is used

Fish, meats, soups, sauces and salads are the classic uses. Flat-leaved parsley flavors dishes in much the way coriander leaves do in Asian cooking.

Parsley is the main ingredient in Levantine tabbouleh, Argentine chimichurri, Italian gremolata and salsa verde, and it’s one of the four French fines herbes, with chervil, chives and tarragon. It also goes into meatballs, stuffings and herb butters.

Technique

Parsley belongs with the delicate herbs best added in the last minute or two of cooking, since long heat costs flavor and aroma. Don’t toss the stems. They carry more flavor than they get credit for and suit stocks and sauces where you can strain them out. LSU’s rule of thumb for swapping fresh herbs with dried is 1 tablespoon fresh to 1 teaspoon dried.⁴ See fresh vs. dried parsley. Overdid it? See too much parsley.

Buying and storage

Look for bright, crisp leaves with no yellowing. We found no sourced shelf-life figure for fresh parsley. See how to store parsley, can you freeze parsley and how to dry parsley.

For dried parsley, PROSEA’s composition table gives 122 mg of ascorbic acid per 100 g.³ We couldn’t retrieve USDA figures for fresh parsley during this review.

Safety

Warfarin

MedlinePlus lists parsley among foods that can change how the blood thinner warfarin works, along with endive, lettuce, spinach, watercress, garlic and scallions. Its advice isn’t to avoid these foods but to eat small amounts and keep the amount steady from day to day.⁵ If you’re on warfarin, follow your prescriber’s guidance.

Seed oil and concentrated preparations

Culinary amounts of the leaf aren’t the concern here. Britannica warns that ingesting parsley seed oil, or large amounts of other parsley preparations, can cause potentially lethal reactions including organ damage, hemorrhage and nerve damage.² PROSEA notes that apiole, the main compound of the seed oil, is an abortifacient, that large doses may cause paralysis and death, and that the fruits taken in large quantities may induce abortion. PROSEA also reports that the aerial parts contain furanocoumarins, mainly bergapten, and that some people who handle parsley regularly develop dermatitis.³

Health claims

Parsley is often said to treat diabetes, osteoporosis and arthritis. We’re not claiming it treats or prevents any condition.

Substitutes and comparisons

See parsley substitutes for ranked options, plus these comparisons:

• Chervil vs. parsley
• Cilantro vs. parsley and coriander vs. parsley
• Basil vs. parsley
• Oregano vs. parsley

Related profiles: chervil, cilantro.

Footnotes

1. Petroselinum crispum, Plants of the World Online, Royal Botanic Gardens, Kew. powo.science.kew.org · Reference work ↩ ↩²

2. “Parsley”, Encyclopaedia Britannica. britannica.com · Reference work ↩ ↩² ↩³ ↩⁴

3. I.B. Ipor and L.P.A. Oyen, Petroselinum crispum, Plant Resources of South-East Asia (PROSEA). uses.plantnet-project.org · Reference work ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

4. “Flavorful Herbs”, LSU AgCenter. lsuagcenter.com · Reference work ↩

5. “Taking warfarin”, MedlinePlus, U.S. National Library of Medicine. medlineplus.gov · Regulator ↩

Also drawn on

• parsley (n.), Online Etymology Dictionary. etymonline.com