Achillea millefolium

Daisy & Dandelion Family [Asteraceae]  

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5th Aug 2017, Hightown brick coastline, Sefton Coast. Photo: © RWD
A barrow of yarrow.

Photo: © RWD
Flower colour can vary from the usual white to various shades of pale pink, to deep pink. However it is contested whether the pale blue specimen recently (2019) posted on Facebook was a true-colour image. But your Author pointed out that Azulene, which is deep blue and contained in Yarrow, might possibly have adversely affected the colour of that specimens petals. It is not without credence, although neither your Author (nor any other botanist) has spotted any blue ones of whatever shade.

10th July 2007, Macclesfield Canal, Macclesfield, Cheshire. Photo: © RWD
Chose the right angle and plants at the edge of the water stand out well against the dark water. Highly frilly leaves at intervals along the stems.

6th June 2015, main road, Aughton, nr. Ormskirk Photo: © RWD
As-yet unopened flowers are quite distinctive. On the central flowers you can espie small parts of the white petals protruding from the tops of the sepals. They are somewhat reminiscent of the un-opened flower buds of Saw-Wort but they are black (very dark purple) with white edges.

6th June 2015, main road, Aughton, nr. Ormskirk Photo: © RWD
Egg-shaped with very pale-green long-white-hairy sepals with dark-brown edges.

8th June 2007, Glenridding Valley, Cumbria. Photo: © RWD
Half of the flower buds are fully opened, the others still displaying their green and black sepals as if advertising premium dark chocolate. The two less advanced side-branches have many long hairs amongst the nascent flower heads (top left). These are definitely not pale pink, but rather a lilac shade which has a hint of blueness (perhaps from the blue Azulene component)

Photo: © RWD
Half-opened flowers. Those branches with inflorescences atop are covered in ants for sopme reason or another. Maybe they are attracted by one of the very aromatic secondary metabolites the plant produces.

21st August 2004, Leeds & L/pool canal side Photo: © RWD
Finely divided fern-like leaves alternate up the stem.

4th Aug 2009, Leeds & L/pool Canal, Burscough, NW England. Photo: © RWD

4th Aug 2009, canalside, Burscough Bridge, Lancs. Photo: © RWD
Pale pink petals.

15th Sept 2006, Kens Boat Trip, Grand Union Canal. Photo: © RWD
Deep pink flowers.

4th Aug 2009, Leeds & L/pool Canal, Burscough, NW England. Photo: © RWD
Back in the Land of Grey and Pink.

4th Aug 2009, Leeds & L/pool Canal, Burscough, NW England. Photo: © RWD
Yarrow has but few disc florets in the centre. The orange 'drumsticks' sticking proud of the central disc floret is the filament and anther of the (usually) single male disc floret. It is surrounded by a few female disc florets with their pairs of pale-yellow stigmas splayed out.

30th Aug 2010, MB&BC canal, Radcliffe, Gtr M/cr. Photo: © RWD
There are very few disc florets in the centre, maybe about 6.

23rd July 2015, Hillside, Sefton Coast. Photo: © RWD
These specimems have an unusually low number of disc florets. The longer protrusions with deep-yellow terminations are the stamens - and is therefore a male disc floret. The shorter 2-pronged pale-cream coloured protrusions are the stigmas and therefore female disc florets.

23rd July 2015, Hillside, Sefton Coast. Photo: © RWD
The 2-pronged stigmas have blobs of pollen on from the taller orange-yellow stamen. There are pollen orange pollen grains on the twinned curved-over pale stigmas.

18th Sept 2008, Rochdale Canal, Castleton area, Lancs. Photo: © RWD
A proliferation of leaves. There are two flowering parts at the rear.

14th May 2008, Leeds & L/pool Canal, Burnley area, Lancs. Photo: © RWD
The pinnate-like leaves are widest in the middle (but if studied closely, the leaflets go in and out of phase with each other on the two sides. A low 'beat-frequency' - so they are not actually pinnate).

22nd June 2007. Photo: © RWD
The very distinctively shaped leaves smell wonderfully aromatic when crushed.

22nd June 2007. Photo: © RWD
The leaves are alternate along the stalk. The leaves themselves are deeply divided which themselves are deeply divided.

21st August 2004, Sedburgh. Photo: © RWD
The white densely hairy stem of a young plant.

Some similarities to : Sneezewort but although the petals are crimped as they are in Sneezewort, there are fewer of them, and the leaves are totally different.

Distinguishing feature : the leaves are extremely distinctive, being fern-like but with very fine narrow leaflets. From close inspection the leaflets are alternate on the stem and tri-pinnate.

Claim to Fame: Along with Gallant Soldier and Shaggy Soldier) this plant has the fewest outer petals of any member of the Daisy and Dandelion Family, totalling a meagre five, apart from those plants which have no outer florets such as Groundsels. Most other members of this family have many more than a dozen outer petals.

Used to flavour beer in Sweden.

Yarrow has been used medicinally for centuries. It is used as a sudorific, to induce sweating, as an antihaemorrhagic to stop wounds bleeding. The Chamazulene in the essential oil exhibits anti-inflammatory and anti-allergenic properties. One of its colloquial names, NoseBleed, gives hint that it finds use as a styptic or haemostatic, both to prevent internal bleeding (when infused and drunk as a tea) and for external bleeding such as from cuts and abrasions. The list of ailments that yarrow has been used to help is almost as long as your arm, many of them confirmed by more modern studies.

Yarrow is not generally considered toxic because the toxic Thujone is just a minor constituent of the oil.

Yarrow also has the ability to accumulate cadmium from the soil, but is not a hyperaccumulator. It is thus a metallophyte which can be useful for the phytoremediation of contaminated land, able to mop up cadmium from the soil, although Bladder Campion (Silene vulgaris) may be more effective for this task if it will grow there, for that is a hyperaccumulator of cadmium.


Yarrow yields an essential oil, which is a deep blue due to the presence of the compound azulene. Amongst 82 constituents are Linalool, Sabinene, the β-Ocimenes trans-ocimene and cis-Ocimene, Azulene, Eugenol, Menthol, α-Pinene, β-Pinene, Borneol, Eucalyptol (aka Cineol) (< 10%), Limonene (< 11%), Camphor (18% - 21%), chamazulene (up to 50%) and prechamazulenes. Terpinen-4-ol, a yarrow oil constituent, has irritant properties and may contribute to its diuretic attributes.

β-Ocimene has a tropical citrus fruit aroma and is a volatile which is the most quickly broken down (out of those volatiles which have been tested) into many reactive species by air pollution, which includes O3, NO2 and CO. As such, it does not travel far from the plants it is released from when there is a little air pollution around, so any signalling or communicating properties it has with other similar and dissimilar plants (or with pollinating insects) are lost.

The various Ocimenes are monoterpenes present in several plants and fruits. Having a pleasant smell they are used in perfumery, stable in oil but un-stable in air tending to polymerise. They are related to Myrcene which is found in Hop.

Many plants contain the terpenoid camphor, including Camphor Laurel and many coniferous trees, but Yarrow contains up to 18% in the flowers. Compare camphor with Camphene, a constituent of Tansy. Camphor readily sublimes and is used in solid air fresheners and medicinally as a rubefacient in vapour rubs, since it is readily absorbed through the skin acting as a local anaesthetic, but is poisonous to eat. Despite its toxicity it has in times past been used to flavour ice-cream and toffees, despite the fact that it can cause respiratory failure in children under 2 years of age! It's smell induces a sensation of coldness, but this is due to it stimulating the cold receptors in the mucous membranes of the nose and lung, and not to any direct de-congestant effect.


Steam Train to Summer Camp by: [the Author]
Azulene out the window
Telegraph poles zip by
In the distance a meadow
And smoke gets in your eye ~

Azulene, found within Yarrow and also in German Chamomile (being Scented Mayweed Matricaria recutita) and Wormwood, is a chromophore with a deep blue coloration. It is an isomer of colourless naphthalene but rather than having two fused six-membered rings, azulene has a seven membered ring fused to one of five members. It is an unsaturated aromatic hydrocarbon, possessing alternate double bonds in resonance. But in order to achieve aromaticity, it donates a π-electron from the seven membered ring to the five membered ring, now making six electrons a piece in each ring which are now able to circulate in resonance without experiencing quantum interference with one other, but at the penalty of making the molecule bipolar: the five membered ring now being negative and the seven membered ring positively charged. This is the energetically favoured configuration for this molecule. It is the continual exchange of the donated electron at a relatively low frequency which imparts the deep blue colour. This is a most un-usual arrangement for a simple organic molecule. Most hydrocarbons are colourless. Azulene crystallizes as dark blue to purple plates. In Spanish, 'azul' means 'blue'. Azulene is also found in Wormwood (Artemesia vulgaris). Guaiazulene is also a deep-blue compound found in Chamomile Oil and is a terpenoid with the azulene skeleton but with three extra side-groups attached, two on the 7-membered ring and a methyl group on the 5-membered ring.

Azulene is used commercially in some ointments as an anti-inflammatory and soothing agent, but advertised as being derived from German Chamomile.

Being polar, in the laboratory Azulene readily forms organo-metallic compounds known as π-complexes with molybdenum carbonyl and iron carbonyl ligands forming (azulene)Mo2/(CO6) and (azulene)Fe2/(CO5).

Naphthalene, (sometimes wrongly spelled 'naphthalein' in the mistaken belief it is related to Phthalein), is a structural isomer of Azulene: both having the same formulae, C10H8. [Naphthalene is shown alongside for comparison only. As far as your Author knows, Naphthalene does not occur in Yarrow]. Naphthalene is a colourless (white) crystalline substance. Azulene, being slightly more energetic than Naphthalene because the electron transfer requires energy, burns in oxygen releasing approximately 2.7% more energy, this excess being due mostly to the bipolar nature of azulene; naphthalene is not bipolar.

Only tetraploid species such as Yarrow contain Azulene, which hexaploid and octaploid species lack. The precursors of azulene in species of Yarrow are prochamazulenes, which confirms that the genera Matricaria (Mayweeds), Artemisia (Mugworts) and Achillea (Yarrows) are all closely related. They are all in the same Daisy Family, but this relationship is closer than that.


Chamomile Blue is another name for the chemical compound Chamazulene which is another chromophore with a deep blue colour which is contained within Yarrow. Chamazulene is an azulene and one of the pre-cursors to Azulene within Yarrow, and is present in the essential oil of yarrow at the high concentration of 50%. It is another anti-inflammatory and anti-allergenic substance used in ointments for eczema, acne and other skin problems. It has an aroma reminiscent of grass, and apples.

It also contains Sesquiterpene Lactones, mainly guainanolides including Achillicin (8-acetoxyartebsin, another proazulene), and Matricine and its derivatives such as α-peroxyachifolid (which has a Peroxide Bridge - highly unusual for a compound produced naturally) and the sesquiterpenoids achimillic acids A, B, and C. Chamazulene is a degradation product of the unstable pro-azulenic sesquiterpene lactones such as Matricine. Like many similar compounds, Matricine also exhibits anti-inflammatory activity.

In addition 15 differing N-AlkylAmides have been found in Yarrow, one of which is called homoSpilAnthol which is also found in Sneezewort. These SpilAnthols are responsible for the medicinal properties of both of these species.


Coumarins such as Umbelliferone and a methoxy analogue of Umbelliferone. Herniarin (7-methoxycoumarine) (± 0.35%) are also constituents of Yarrow. Herniarin is one of the chemical pheromones used by insects. It is also one (amongst a few others) of the sensitizers of contact dermatitis in German Chamomile (from which a herbal tea is brewed) which could result from handling German Chamomile. Both Coumarin and Herniarin also occurs in Lavender as a glycoside, which yields Herniarin on enzymatic attack or hydrolysis.


Yarrow contains several flavonoids: Apigenin, Luteolin, Rutin, Artemetin and Casticin.

Artemetin is also found in the non-UK herb Cordia verbenaceae of the Borage Family and has anti-inflammatory activity coupled with a low toxicity.

Casticin (or Vitexicarpin) is also found in Beach Vitex (Vitex rotundifolia, a plant not found in the UK belonging to the Dead-Nettle Family) and has the ability to block the effects of histamine (the irritant substance generated in the allergic response) and as such may have applications for disorders such as rheumatoid arthritis where its ability to act as an anti-inflammatory is called upon. It will also inhibit the growth of certain cancer cells.

The two shown differ only in a hydroxyl group and a methoxy group (top right).


Amino Acids present in Yarrow include Alanine, Histidine, Aspartic Acid, Glutamic Acid and Lysine.

Note that Lysine is Cadaverine with an acid carboxyl COOH group attached to one of the last carbon atoms in the chain. Indeed, Cadaverine is the decarboxylation product of Lysine.

Nutritionally, Histidine is an essential amino acid for infants until they begin to manufacture it themselves after reaching several years of age. Histidine is the pre-cursor to Histamine and Carnosine (an anti-oxidant, amongst its many other roles, present in muscles and brain) synthesis in the mammalian body. Histidine is converted by an enzyme in the body (histidine ammonia lyase) into ammonia NH3 and Urocanic Acid, a substance which is sweated out onto the skin as a natural UV-B sun-screen and which also activates suppressor T-cells against skin cancer.


Achiceine, Achilleine, Achilletin and Moschatine have all been reported to be constituent alkaloids of Yarrow, but of these, the Author has only found the structural formula for Moschatine, shown above, which is not an alkaloid but a glycosidic steroid. (Moschatine should not be confused with the similar sounding Moschatin (no terminal e) which is a ribosome-inactivating protein). Moschatine is a complex and most unusual glycosidic steroid found in Sweet Sultan (Centaurea moschata) which is an ornamental plant of the Daisy Family non-native to the UK. A report by Hakan Tunon in 1998 states that Moschatine is a betaine (and not a glycosidic steroid) being N-methyl piperidine-2-carboxylic acid methyl betain, and is not one of the alkaloids found in Yarrow. Thus it is obvious there are name clashes here. Tunon also reports that there is much confusion in the literature about the alkaloids reputedly found within Yarrow; he finds only four or five alkaloids.

[This confusion is typical in the literature of substances found within plants. Your Author endeavours to eliminate as much confusion as possible by showing the structural formulae for the reported substances. If a structural formula cannot be found anywhere, then this is a clue that the reported substance is probably erroneous (or has been given another much more common name which is already known). Thus, if I do not show the structural formula anywhere on this website, then either the substance may be an aberration and should be treated with suspicion, or it may simply be that I have not yet got around to drawing the structural formula for it] Your Author.

The only four (or possibly five) alkaloids which Tunon finds in Yarrow are betains, namely:
Betonicine (aka Achilleine) is a betaine alkaloid found also in Betony (and is related to Betaine) Betaine itself, Choline (Choline Chloride) and Stachydrine (aka Leonucardine) with possibly Trigonelline as the fifth. He further notes that all other reports of alkaloids are either synonyms of the above, or crude mixtures, or from differing Achillea species.

Betonicine is the laevo variety of Turicine (which is the dextro variety).


Variously the Guaianolide peroxides, as well as polyacetylenes (such as pontica epoxide), α-peroxyachifolid and 16- 10- sesquiterpene lactones in yarrow that have been attributed to the contact dermatitis that is commonly associated with handling Yarrow.

Pontica Epoxide is a polyyne with three triple bonds which is found in four different species of Artemesia (Mugworts) as well as three of Chrysanthemum and of course Yarrow. Having triple bonds in it naturally makes it highly poisonous. Un-like the polyynes in Ivy (Falcarinol), Cowbane (Cicutoxin), Fools Parsley (Aethusin) and Hemlock Water-Dropwort (Oenanthotoxin), Pontica Epoxide within the Daisy Family has a very low concentration; Yarrow is relatively innocuous.

Anacyclin is a poisonous polyacetylene and alkaloid found in the roots of Yarrow and was first discovered in Spanish Chamomile (aka Mount Atlas Daisy) (Anacyclis pyrethrum) a non-native plant which is also in the Dandelion & Daisy Family (Asteraceae). It is similar to Cicutoxin, another polyacetylene which is the poisonous principle of the Umbellifer Cowbane (Cicuta virosa).

N.B. Anacycline should not be confused with a generic pharmaceutical of the same name, which contains a number of steroidal substances such as Lynestrenol and Ethinyl Estradiol and which does not contain anacyclin the polyyne.

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Achillea millefolium

Daisy & Dandelion Family [Asteraceae]  

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