Name currently accepted: Petroselinum crispum

Authority: (Mill.) Fuss

Taxonomic serial no.: 822347 (ITIS, 2016)

Synonyms: Apium crispum Mill., Apium petroselimum L., Apium petroselimum var. angustifolium Hayne; Apium petroselinum var. variegatum Nois; Apium petroselinum var. vulgare Nois., Carum petroselinum (L.) Benth & Hook. f., Cnidium petroselinum DC., Petroselinum crispum var. angustifolium (Hayne) Reduron, Petroselinum crispum f. angustifolium (Hayne) Danert, Petroselinum crispum f. variegatum (Nois) Danert, Petroselinum crispum f. vulgare (Nois) Danert, Petroselinum crispum var. vulgare (Nois) Danert, Petroselinum hortense Hoffm., Petroselinum petroselinum (L.) H. Karst., Petroselinum sativum Hoffm., Petroselinum sativum var. variegatum (Nois) Alef., Petroselinum sativum var. vulgare (Nois) Alef., Petroselinum vulgare Lag., Peucedanum petroselinum (L.) Desf., Selinum petroselinum (L.) E.H.L. Krause, Wydleria portoricensis DC. (Anon., 2010).

Family: Apiaceae (Kingdom: Plantae; Subkingdom: Viridiplantae; Infrakingdom: Streptophyta; Superdivision: Embryophyta; Division: Tracheophyta; Subdivision: Spermatophyta; Class: Magnoliopsida; Superorder: Asteranae; Order: Apiales; Family: Apiaceae; Subfamily: Apioideae; Tribe: Apieae; Genus: Petroselinum; Species: crispum; Binomial: Petroselinum crispum (Mill.) Fuss).

Parsley is a culinary and medicinal herb that has a very long history of use by humankind from ancient times. Its original home is the western Mediterranean region and northern Africa. It is found naturalized and also grown widely in most temperate and subtropical countries. On a small scale, parsley is cultivated in tropical regions at higher elevations where the climate is cool. The herb is grown for its leaves, seeds and also for the swollen taproot that is characteristic of the variety, turnip-rooted parsley. Parsley was more of a medicinal herb in ancient Greece and Rome and its spread to the various European regions was probably during the 15th–16th centuries, when parsley became a popular flavouring herb and a valuable herbal remedy. During the course of domestication and spread of the crop, many cultivars and morphotypes have evolved. Common parsley includes about six groups, differentiated on the basis of morphology and uses, two of which are widely grown. Common parsley (crispum group), is the most extensively grown, the largest producers being the USA, and West and East Europe. Variety neopolitanum is more common in Italy and Libya where its fleshy petioles and ribs are eaten as a vegetable. The radicosum type is grown for its swollen turnip-like taproots, which are eaten cooked as a vegetable and used in soups or sometimes dried and ground into powder for use as a flavouring agent. The vulgare group is also known as common parsley or flat-leaved parsley (or plain-leaved parsley). It is grown on a small scale in Eastern Europe, Germany, the Netherlands, Denmark, the UK and the USA.

Most commonly, parsley is grown as a backyard herb, and commercial farms cater to the needs of cities and towns. It is perhaps the most widely grown and used herb in many European countries as well as in certain Southern Ocean and Pacific Ocean countries (Ipor and Oyen, 1999; Anon., 2014c).

Parsley was used in ancient times for ritual purposes. The Greeks used parsley in funerals and for wreaths long before it was used as a food plant. The Romans used parsley at orgies to disguise the smell of alcohol on their breath. Corpses were once sprinkled with parsley to deodorize them. Later parley became associated with evil, negative consequences and Satan. Virgins were not allowed to plant parsley for fearing of losing virginity to the evil. In the past, parsley seeds were sown on Good Friday and only the elderly people of households used to sow the seeds (Charles, 2012; Anon., 2013).

The species description is based mainly on the Flora Nordica (Fröberg, 2016), Flora of China (She and Watson, 2005) and the PROSEAbase (Ipor and Oyen, 1999). Parsley plants are erect, branched and aromatic herbs, cultivated as annuals or biennials, but can also be grown as a short-lived perennial when treated to regular harvestings, followed by copious irrigation. The plant grows to 30–100 cm tall. Roots are fibrous in the case of common parsley or swollen and turnip-shaped in the case of the variety tuberosum. The leaf differs in size and shape and forms the criteria for the division of some of the varieties, mainly the curly leaved (crispum) and flat leaved (vulgare) types. The radical leaves are a rosette of leaves when young. The stem is terete, sulcate and hollow; leaves are alternate, 1–3 pinnately compound, glossy, flat or curly shaped and sheathing at the base. The petiole is the longest in lower leaves, the pinnae are long-stalked and leaflets obovate–cuneate to finely linear; later formed leaves are less divided, with the topmost one consisting of a few segments only.

Inflorescences are terminal or axillary compound umbels. The peduncle is up to 12 cm long, primary rays are 5–20, 1–5 cm long and secondary rays (pedicels) are 3–15 and 2–5 mm long. Flowers are small, bisexual, yellow–green and the calyx is obscure; the corolla consists of five petals, each one sub-orbicular to obovate with an inflexed apical lobe. Stamens are five; the ovary is inferior and bicarpellary, and each carpel has a thickened stylopodium, a style and a small globose stigma. Wasp and hoverfly species pollinate the parsley florets. The fruit is a schizocarp, ovoid, 2–3 mm long, splitting into two mericarps at maturity, each one with five narrow ribs. The chromosome number is 2n = 22 (Ipor and Oyen, 1999; She and Watson, 2005; Anon., 2014a; CCDB, 2016; Fröberg, 2016).

Parsley is an ancient crop, cultivated worldwide and exhibiting much variation in habit, size, leaf form and root thickness and shape. The crispum group has curly leaves and compact branches; it is the most widely cultivated and used mostly as a garnish and in salads. Common cultivars include: perfection, banquet, forest green, decorato, Afro, moss curled, deep green, improved market gardener and dark moss-coloured. The neopolitanum group forms the Italian parsley; it has more open branches and flat leaf blades. Its flavour is stronger than that of the crispum group and hence it is used for flavouring sauces, soups, stews and so on, where a strong flavour is desired. Its cultivation is restricted to some regions in Italy and adjoining regions. Important cultivars are: plain, plain-Italina and dark green. Turnip-rooted parsley forms the radicosum group; it possesses long fern-like leaves, is robust and has swollen turnip-shaped roots. It is cultivated mainly for its roots; the leaves are also used for flavouring. Well-known cultivars are: early sugar, fakir and Hamburg thick-rooted. Vulgare group parsley is also flat leaved and similar to the Italian type but smaller in stature; it is also known as common parsley and common flat-leaved parsley. Inter-generic hybridization with celery has resulted in hybrids with novel quality factors and flavour characteristics such as the well-known hybrid Festival 68. Parsley is grown through seed sowing; seeds are to be soaked for 2–3 days prior to sowing. The plants while growing are to be cut periodically to prevent flowering and seeding (Ipor and Oyen, 1999; HAS, 2012; Anon., 2014a).

Apart from carbohydrates, proteins and lipids, parsley contains many chemical constituents such as flavonoids, mono-, di- and triterpenoids, coumarins and miscellaneous compounds. Many flavonoids are reported, such as: apigenin, luteolin, quercetin, isorhamnetin, chrysoeriol, cosmosiin, apiin, acetylapiin, petroside and its monoterpene glucoside, cnidilin, and kaempferol and its glycosides (Kreuzaler et al., 1973; Yoshikawa et al., 2000; Chaves et al., 2011). Coumarins and furanocoumarins present in the plant and seed include the oxypeucedanin psoralen, 8-methoxypsoralen, isopimpenellin, imperatorin and isoimperatorin (Chaudhary, et al., 1986). Parsley contains an essential oil: 0.02–0.9% in leaves and 2–8% in seed. These essential oils contain a large number of volatile constituents that include: myristicin, apiol, α-pinene, sabinene, β-pinene, p-cymene, limonene, β-phellandrene, γ-terpinene, elemicin, 1-allyl-2,3,4,5-tetramethoxybenzene, carotol, eugenol, etc. The leaf essential oil contained β-elemene, β-caryophyllene, phenylacetaldehyde, γ-elemene, α-terpineol, α-pinene, α-thujene, camphene, sabinene, δ-3-carene, myrcene, α-phellandrene, β-phellandrene, α-terpinene, limonene, cis-β-ocimene, trans-β-ocimene, γ-terpinene, p-cymene, α-terpinolene, α-cubebine, δ-cadinol, etc. (MacLeod et al., 1985; López et al., 1999; Zhang et al., 2006; Farzaei et al., 2013). In general, the percentage composition of major components of the oil are (% in leaf oil and seed oil, respectively): α-pinene (26.42, 15.73), sabinene (1.1, 0.64), β-pinene (18.04, 10.01), myrcene (4.24, 0.22), α-phellandrene (0.51, 0.12), β-phellandrene (6.48, 2.14), terpinolene (2.52, 0.01), p-mentha-1.3,8-triene (16.41, 0.12), myristicin (11.92, 39.65), elemecin (2.71, 4.84), 2,3,4,5-tetramethoxyallybenzene (0.72, 7.82) and apiol (0.27, 18.32) (Quave, 2013).

Parsley contains psoralen and related compounds that can induce photosensitivity. These include ficusin, bergapten, majudin and heraclin. Antimicrobial compounds present in parsley are 8-methoxypsoralen, 5-methoxypsoralen, oxypeucedanin and isopimpenellin. Parsley contains the estrogenic flavone glycosides 6′-acetylapiin and petroside (Pathak et al., 1962; Manderfeld et al., 1997; Yoshikawa et al., 2000).

Parsley is well known as a medicinal plant in several traditional medicine systems. Several properties are attributed to parsley; a long list of activities is provided by Duke (2002). A few of the more important properties are mentioned here.

• Anti-oxidant activity: Animal studies showed that feeding parsley leaves led to an increase in anti-oxidant enzymes. Apigenin was demonstrated to be the main compound responsible for the anti-oxidant activity. Seed oil also exhibited in vitro anti-oxidant activity. Apiol and myristicin present in the seed oil were indicated as responsible for this effect (Nielsen et al., 1999; Zhang et al., 2006; Farzaei et al., 2013).
• Anti-diabetic activity: Parsley extract enhanced blood anti-oxidant function in CCl₄-induced oxidative stress in mice models. Parsley leaves and extracts decreased blood glucose level and demonstrated hepato-protective activity in diabetic rats. Parsley improved hyperglycaemia-induced heart and aorta oxidative damage through its anti-oxidant activity, but did not show any effect on non-enzymatic glycosylation of skin proteins in diabetic rats (Tunali et al., 1999; Sener et al., 2003).
• Analgesic and spasmolytic activity: Parsely hydroalcoholic extract exhibited analgesic activity and reduced KCl- and CaCl₂- induced contractions on isolated rat ileum dose dependently. An extract of the aerial part showed anti-spasmodic activity on spontaneous and acetylcholine-induced contractions of rat isolated ileum (Branković et al., 2010).
• Immuno-modulating activity: Parsley exhibited an inhibitory effect on phytohaemagglutinin-stimulated splenocytes that might be due to the production of cytokines such as gamma interferon and interleukin-2 that are vital for T-cell proliferation or it might influence the signalling pathways. Parsley essential oil can modulate the activity of macrophages without causing any cytotoxic effect (Karimi et al., 2012; Yousofi et al., 2012).
• Gastrointestinal activity: An ethanol extract of parsley leaves exerted beneficial effects on different models of peptic ulcer in rats via its anti-secretory and cytoprotective activity. An aqueous extract of parsley seeds demonstrated a laxative activity in rat by the significant absorption of sodium and water and also by enhancing Na–KCl transporter activity in the colon (Kreyddeh et al., 2001; Al-Howiriny et al., 2003). Nair et al. (2015), from their studies on animal models, concluded that parsley could attenuate the development of non-alcoholic fatty liver significantly.
• Anti-proliferative activity: A methanol extract of the parsley aerial part showed proliferative activity in the oestrogen-sensitive breast cancer cell line (MCF-7) equal to isoflavone glycosides from soybean. This oestrogenic activity was related to the flavone glycosides, 6′′-acetylapiin and also to the aglycones such as apigenin, diosmetin and kaempferol (Yoshikawa et al., 2000).
• Reproductive system effects: Parsley extract resulted in an increase in uterus weight in ovariectomized mice. This property is exerted by the apiin and apigenin present in the extract. Parsley oil had a significant protective activity against certain chemically induced reproductive toxicity and improved significantly the testosterone level, sperm count and sperm motility and inhibited germ cell chromosomal aberrations. An aqueous extract also induced a diuretic effect and inhibited Na⁺, K⁺ ATPase activity in the kidney cortex and medulla (Yoshikawa et al., 2000; Kreydiyyeh and Usta, 2002; Abdel-Wahaab et al., 2006).
• Other activities: Parsley leaves decreased mean blood pressure in anaesthetized rats. It also decreased the rate and amplitude of contraction of isolated rat atria. Such studies indicated hypotensive and negative inotropic and chronotropic activity of parsley extract. An anti-platelet action was also demonstrated (Brankovic et al., 2008; Gadi et al., 2009; Chaves et al., 2011). In addition to the above, parsley also possesses antimicrobial and cytotoxic activities (Kim et al., 1998; Farzaei et al., 2013).

Sensitive people can be allergic to parsley and those who are allergic to plants of Apiaceae (carrots, celery, fennel, etc.) should avoid its use. In such people, parsley can cause skin inflammation. Parsley can enhance photosensitivity and those who use parsley paste and infusion externally should not expose themselves to direct sunlight (Anon., 2011, 2014d). Duke (2002) covers details of the safety aspects of parsley.

The use of parsley seeds, herb, oil and oleoresin could lower blood sugar levels. Caution is advised in patients with diabetes or hypoglycaemia and in those taking drugs, herbs or supplements that affect blood sugar while using parsley. Parsley can cause an increased risk of bleeding, hence caution is advised in patients with bleeding disorders or taking drugs that may increase the risk of bleeding. Parsley might cause low blood pressure. It may also have effects on the gastrointestinal system and those with gastrointestinal disorders should be careful while using it. Parsley oil could cause uterine contractions and miscarriage; pregnant women should avoid parsley oil, oleoresin and seeds (Duke, 2002; Anon., 2011, 2014d).