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Laurus nobilis

Bay Family [Lauraceae]

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bay leaf

2nd Sept 2017, the spaceship, Blundellsands, Sefton Coast. Photo: © RWD
A shrub or short tree growing from 10 to 18m tall (the greyer leaves bottom left are of another plant)

2nd Sept 2017, the spaceship, Blundellsands, Sefton Coast. Photo: © RWD
Young shoots are directed upwards. The leaves are also upwardly pointing, but not vertically.

2nd Sept 2017, the spaceship, Blundellsands, Sefton Coast. Photo: © RWD
Leaves stiff and thick, 5-10cm long, with a stiff mid-rib underneath.

2nd Sept 2017, the spaceship, Blundellsands, Sefton Coast. Photo: © RWD
Leaves laurel-like and lack hairs; glossy on the upperside, possibly with slightly wavy edges.

2nd Sept 2017, the spaceship, Blundellsands, Sefton Coast. Photo: © RWD
 Un-opened flower buds. It is a dioecious species, with male and female flowers on separate plants. This shrub has fruit, but these are a small cluster of as-yet, un-opened flower buds, so they must be of female flowers.

2nd Sept 2017, the spaceship, Blundellsands, Sefton Coast. Photo: © RWD
 Flower buds in small groups nestle in the leaf axils.

2nd Sept 2017, the spaceship, Blundellsands, Sefton Coast. Photo: © RWD
 Flower buds showing the sepals enclosing it.

2nd Sept 2017, the spaceship, Blundellsands, Sefton Coast. Photo: © RWD
 Each flower stalk also has bracts covering from whence it grew.

2nd Sept 2017, the spaceship, Blundellsands, Sefton Coast. Photo: © RWD
 Proving this is a female shrub are the fruits, which are green at first and blacken to a prolate spheroidal (rugby ball) shape.

2nd Sept 2017, the spaceship, Blundellsands, Sefton Coast. Photo: © RWD
 The fruits, which have tiny paler spots on its surface, nestle on a wide 'pedestal'. They are not edible.

2nd Sept 2017, the spaceship, Blundellsands, Sefton Coast. Photo: © RWD
The obverse of the leaf is not glossy like the upper side, but still lacks hairs (left). The veins by transmitted light (right)

2nd Sept 2017, the spaceship, Blundellsands, Sefton Coast. Photo: © RWD
The leaf veins by transmitted light.

24th April 2008, Gasworks Lane, Great Yarmouth. Search: Photo: (CC by 2.0) Mike Cotterill
 Judging by the numerous stamens this is a male plant.

24th April 2008, Gaswworks Lane, Great Yarmouth. Search: Photo: (CC by 2.0) Mike Cotterill

Easily confused with : other Laurels such as Cherry Laurel (Prunus laurocerasusant) or Portugal Laurel (Prunus lusitanica) which are in the Rose Family Roseaceae or Spotted Laurel (Aucuba japonica) which is in the Spotted-Laurel family Garryaceae [differing species with similar names which are all toxic]

Not to be semantically confused with : Bay Willow (Salix pentandra) another tree/shrub with a similar name. Nor with Stan Laurel, although the plant is Hardy...

Uniquely identifiable characteristics:

Distinguishing Feature : the distinctively aromatic leaves.

Your Author noticed, when pruning some branches off which were complete with leaves, that it smells of Ginger, or more precisely, of Crabbies Ginger Wine. He knows not why.

Bay leaves are very aromatic and are used in cooking, as a flavouring in Lancashire Hotpots and soups. But they are very tough and inedible (even after cooking for extended periods) and are usually removed before serving. Only a few, 2 or 3 leaves are used, any undesirable toxins they may contain are insufficient to cause harm when used this way.

The shrub or short tree is not often found spreading wild, but is a neophyte which arrives sporadically, possibly by bird seed, but plantings are also common for culinary purposes (your Author has one in his garden, but it has never flowered - so he has no idea whether it is male or female). It is found usually near the coast on cliffs but also in scrub.

It is dioecious, with separate male and female plants. The flowers are small, about 1cm across, and fairly quickly change from creamy coloured to a pale brown. The male flowers have an inner ring of 5 cream-coloured filaments with a yellow anther atop - each with a pair of nectaries each side. A second and concentric outer ring, has 7 anthers but without any associated nectaries. So, altogether, 12 anthers, arranged a bit like a miniature stonehenge. The nectar secreted by the nectaries consists mainly of sucrose together with a mixture of other substances such as enzymes, amino acids, mineral salts and secondary metabolites which are highly variable. The male flowers secrete the most nectar and have the more open flowers: the stamens push the petals wider apart.

The female flowers have a ring of 4 staminodes (sterile reduced stamens) each with a nectary each side. These surround a greenish single central style atop of which is a large white discoidal stigma with a smaller brownish patch.

Male or female, both sexes of flower have 4 cupped petals around them (they could be tepals?). From opening, any individual flower only lasts about 6 days before senescence, but other flowers are ready to open over perhaps a 2 month period. Male flowers last a day shorter (~6 rather than ~7 days), but the pollen is only viable for a day.

So, to borrow a term from chemistry, between them, the flowers exhibit valences of 1, 2, 4, 5, 7 and 12 (but not as many as   Manganese has, which is 11).


The main monoterpenoids in Bay (as a fractional percentage of the essential oil extracted from the leaves) as reported in one analysis are: Eucalyptol (aka 1,-8-Cineole) at 69%, Limonene 3%, Sabinene 2%, α-Terpinene 2%, p-Cymene 2%, α-Pinene 1.7%, γ-Terpinene 1.6%, Camphene 1%, trans-PinoCarveole 1%, α-Terpinolene 0.8%, Phellandrene 0.74%, PinoCarvone 0.53%, p-Ment-1-en-8-ol 0.6%, Linalool 0.43%, Geosmin 0.22%, (2-MethylProp-1-enyl)-cycloHexa-1,3-Diene 0.14%, 4-Ethenyl-1,2-DiMethyl Benzene 0.11%, 5,5-DiMethylCycloPentaDien 0.06%, 5,9,9-TriMethyl-Spiranol[3,5]Non-5-en-1-on 0.03%, p-Ment-1-en-3,8-Diol 0.04%, 3-Hexane-1-ol 0.06% plus other chemicals with names far too long to mention.

Another source quotes this as his analysis of Bay: Eucalyptol 60%, α-Terpinyl Acetate 9%, Terpinene-4-ol 4%, α-Pinene 3%, β-Pinene 3%, Sabinene 3%, ortho-Cymene 1.3%, para-Cymene 1.8%, Cuminaldehyde 0.2%, Linalool 0.2%, Myrcenol 0.1%, DiMethylStyrene 0.08%, Eugenol 0.16%, Methyl Eugenol 0.05%, Carvacrol 0.05%,

Yet others report α-Terpinyl Acetate, Methyl Eugenol and Linalool, both cis and trans forms of Thuj-2-en-4-ol.

This all goes to emphasise the great variability other factors play on the composition. Factors might include climate, weather, soil, air quality, and numerous others.


This is a para-Menthene monoterpenoid with a HydroPeroxy group substitution at the top (position #1) and an Acetyloxy group substitution at position #8. It is found, perhaps exclusively(?), in the leaves of Bay Laurel and exhibits trypanocidal (anti-protozoan) activity against Trypanosomes, which include those from Tsetse flies which causes 'sleeping sickness' in humans.

Another source says that the main odorous components of the leaf oil are 3 monoterpenoids: Chavicol, Eugenol and Myrcene.
Chavicol aka para-AllylPhenol is a PhenylPropene and is an alcohol used as an odourant in perfume and for flavouring. The methyl derivative, Methyl Chavicol, is found in Basil

Eugenol is Chavicol with the addition of a methoxy group on the benzene ring and is the main ingredient found in Clove Oil (at up to 80-90% of Clove-bud oil and only slightly less in Clove Leaf oil), Nutmeg, Cinnamon, Basil, Balsam of Peru and Bay. In the mouth Eugenol numbs the mouth (as does chewing cloves) and is used as both a local antiseptic and a local anaesthetic, particularly in dentistry. Eugenol is also used in flavourings and in perfumes. The smell of Eugenol attracts male orchid bees who consume it in order to synthesize pheromones. It is probably no coincidence that the Orchids in the Gymnadenia genus are able to synthesise both Eugenol (and its isomer, IsoEugenol) by means of a gene they produce. This is particularly noticeable in the orchid genus Gymnadenia odoratissima (one of the Fragrant Orchids, which has only once been seen in the UK but never confirmed).
It may come as a surprise to find that Eugenol is hepatotoxic, with a toxic dose in the region of 500-1000mg/kg of body weight (which is one third that of common table salt - ie it is thrice as toxic as salt). But there are only a few cloves put in hot-pots, soups, curries, rhubarb pies, rice-puddings and spirits. Cloves are the fried flowers of an Indonesian tree in the Myrtaceae family called Syzygium aromaticum. Cloves contain the (probably red coloured as are Clove flowers when open) Chromenone called Eugenitin, a sesquiterpenoid with two fused 6-membered rings.

Myrcene is a monoterpene which is also found in both Hop (Humulus lupulus) and in Cannabis (Cannabis sativa), which both belong in the same Cannabacceae family, but not in the same genus. It is also found in a great many other plants including Rose and some Orchid flowers as well as Garden Angelica, Bay, Lawson's Cypress, Ground-Elder, Goldenrod, Golden Samphire, Vervain, Woormwood and Yarrow to name but a few. Myrcene smells peppery with a woody scent and a hint of carrot. It degrades quickly in the presence of Nitrogen Dioxide gas which is present in the air at parts per million concentrations and is emitted by from diesel engines. This is bad news for Myrcene is very likely a messenger and signalling molecule broadcast to pollinators to attract their attention and probably interpretated by other plants for reasons as yet unknown. Even just a few ppm of NO2 will degrade the myrcene into a plethora of other radicals and moieties before it travels a few metres from the plants.


DeHydroCostusLactone is also found in Lesser Burdock (Arctium minus)

Zaluzanin D is based upon Zaluzanin C, which has no reported presence in Bay. Zaluzanin C possesses an Azulene skeleton (with several side-groups attached) to which is fused a Furanone, the lactone-containing moiety.

Zaluzulin D, which is found in both Bay Laurel and in Zaluzania triloba which has no presence in the UK. Differing from Zaluzanin C only by the addition of an extra group attached at position #8, an Acetyloxy group. This also exhibits trypanocidal activity. It is a fungistatic (compounds which inhibit the growth of fungi but without killing them) and a sesquiterpenoid - found as a major constituent (0.4%) in the aerial parts of Veronica arborea (which does not grow in the UK) and in Bay. They both induce apoptosis (cell death) in Leukaemia HL-60 cells.


Costunolide is also found in Bay Laurel and has the Germacranolide skeletal structure (with an unfused 10-membered ring attached to a 5-membered lactone ring as depicted). As can be seen, in comparison to both Santamarine (and Reynosin) and the Zaluzanins, it is lacking a cross-link and contains instead a 10-membered ring. That cross-link could be put anywhere: if it is put half-way then the Santamarine/Reynosin type of lactones result with two fused 6-membered rings. If, however, the cross-link is put elsewhere, then the Zaluzanins and CostusLactone form might be produced. These have fused 5- and 7-membered rings, as does Azulene. Costunolide is also found in Lettuce but was first found in Costus (Saussurea costus) a South Asian thistle.

Reynosin is another Sesquiterpene Lactone belonging to the Eudesmanolide group. It is found particularly in Bay Laurel and in Magnolia grandiflora, another tree much more decorative than bay and therefore much more often planted in gardens but which does not grow wild in the UK.

Santamarine is also found in the garden tree Magnolia grandiflora and in Feverfew (Tanacetum parthenium) and has a similar skeletal structure as Parthenolide which is found in Feverfew. Santamarine exhibits anti-cancer activity. Anti-mycobacterial activity against Mycobacterium tuberculosis (Mtb) is possessed by both Reynosin and Santamarine, but Reynosin is the more active.

Another Eudesmane derivative it contains is named as: 3-alpha-AcetoxyEudesma-1,4(15),11(13)-trien-12,6-alpha-+++olide, but your Author could not be bothered figuring out the chemical structural formula of it. The same is true for the alpha-Santonin derivative it also contains: 3-OxoEudesma-1,4,11(13)-trien-12,6-alpha-olide.

  Laurus nobilis  ⇐ Global Aspect ⇒ Lauraceae  

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Laurus nobilis

Bay Family [Lauraceae]