Easily confused with : Yew [a bush with similar height, jizz and leaves, but the leaves of (most species of) Common Juniper are sharp (to the point of hurting) at the tip]
Easily mistaken for :
Chinese Juniper (Juniperus chinensis) but has leaves in two differing forms. Young leaves look similar to the needle leaves of Common Juniper, but are less sharp, and peel away gradually from the stem rather than at right-angles. But older specimens lack these needle leaves altogether and have knobbly green bulges (scale leaves) along the stem much like many
Cypress bushes possess.
Common Juniper comes in three sub-species:
Your Author was told that those Junipers shown on here which your Author found east of Coniston Lake in the Torver Common area are of 'Hybrid Juniper'. Unfortunately, there is no 'Hybrid Juniper'!!
- Juniperus communis ssp. communis - Spreading shrub to erect tree. Leaves tapering to a very sharp point! Underside of leaf (in stomatal band) grey-white. Very localised, but found throughout much of Britain and Ireland on either acid or limestone soils. Absent from most of South West Britain, Central and Southern England.
- Juniperus communis ssp. hemisphaerica - Low compact shrub, not a tree. Leaves tapering to a very sharp point! Underside of leaf (in stomatal band) pure-white. Found only in sea cliffs of West Cornwall. [Similar plants found in Pembrokeshire are probably extreme forms of ssp. communis]
- Juniperus communis ssp. nana (
Dwarf Juniper) - Procumbent matted shrub, lower than either above. Leaves abruptly tapered so that the point is not sharp or painful to touch like the other 2 above. Underside of leaf (in stomatal band) pure-white. Found in NW Wales, NW England, West & North of Ireeland, Central & NW Scotland.
Your Author thinks the above photos are all of Juniperus communis ssp. communis. (Now confirmed as true for all 17 photos).
The bark or berries of Juniper yield a brown dye when using chrome mordants.
Common Juniper (or just Juniper) is by far the most common, but is in decline in the Lake district where it is commonly found due to the grazing of seedlings by sheep. A program of planting is underway under the stewardship scheme in an attempt to halt the decline in these areas. Chinese Juniper is only found in very few hectads in England. A sub-species of Common Juniper,
Dwarf Juniper (Juniperus communis subsp. nana), is found in Cumbria and in Western Scotland and Snowdonia. Another sub-species Juniperus communis subsp. hemisphaerica, is found in only 4 hectads in the extreme west of Wales and Cornwall.
The plant smells aromatic when crushed. It has blue-black cones which look more like berries, and indeed are often called 'Juniper Berries'. These cones look similar to the bluish berries of Blackthorn, but are about half the diameter, and look more like black peppercorms when ripe. The cones are used for culinary purposes, and are put in spirits to impart the 'gin' flavour of gin. Indeed, the word 'Gin' is derived from the name Juniper. Juniper berries are also used as a spice. They are extremely hard and normally require grinding in a spice mill. The spice is a popular flavouring agent for Quail, Pheasant, Rabbit, Venison, Veal and other meat dishes.
Juniper trees are popular as bonsai plants, for they readily form contorted and old-looking tree-like shapes when miniaturised.
The flowers are small and yellow, and usually appear on separate shrubs. It is found on low Western coastal cliffs and on heaths and moorland in the west.
Skin contact with Juniper leaves (they are sharp and prickly) (or with the wood) can cause erythema and skin irritation in some individuals, sometimes leading to blisters or even to excessive burns. This is a hypersensitivity response. The same is true for the essential oil of Juniper. It is probably caused by phenolic compounds found within.
Juniper is dioecious with male and female flowers appearing on separate plants.
The essential oil distilled from the berries contains the following: 40.5% α-Pinene 40.5%, 18% Sabinene, 13.5% Myrcene, 5.1% Limonene, 2.5%
1-Terpinen-4-ol, 2.3% para-Cymene, 2.2%
BicycloGermacrene (aka Lepidozene), 1.2% Terpinolene (aka delta;-Terpinene), 1.1% β-Elemene, 1.0%
α-Cubebene, 0.6% β-Caryophyllene, 0.6% α-Humulene, 0.6% γ-Cadinene, 0.6%
δ-Cadinene and 0.1% Germacrene D. There were 8.6% un-identified components of which α-Thujone was possibly a small component.
The oil obtained from the leaf differs from that in the berries. Again, α-Pinene was the major constituent at 38%, but
α-Cedrol was the next most abundant at 31%. Monoterpenes accounted for a total of 41%, followed by oxygenated sesquiterpenes at 32%.
Oils obtained from both leaf and berries are used in perfumes. A tea can be made from Juniper Berries which aids digestion, but also has a diuretic effect thought to be due to the presence of Terpinen-4-ol.
Because Oil of Juniper is expensive to produce, it is frequently adulterated, which can make it very toxic!
There are four isomers of
γ-Terpinene and δ-Terpinene which depend on the positions of the two double-bonds. They are known as Terpenes. As far as has been ascertained β-Terpinene is not found in the natural world. Juniper contains γ-Terpinene and δ-Terpinene (which is otherwise also known as Terpinolene). α-Terpinene is found in
Cardamom and Marjoram but not Juniper.
SESQUITERPENES and SESQUITERPENOIDS
Cadinene has several isomers including α, β, γ, δ and ε which also depend on the positions of the two double-bonds. (β-Cadinene and ε-Cadinene seem to be relatively uncommon). They have the Cadalane skeleton. If stereoisomers are included, then there are many more isomers, with each set of stereoisomers having one of four names: Cadinene (as here), Muurolene, Amorphene and Bulgarene, depending only upon the stereo-positioning of the two lone hydrogen atoms. Juniper contains only Cadinenes, and only two out of the three. The Cadinenes were originally discovered in Cade Oil, hence the name. See Cadinene for fuller explanation. Some isomers of Cadinene are used as flavours and in perfumes.
Cubabene, instead of possessing two double bonds of the Cadalane skeleton has but one double bond. In place of a second double-bond it has a 'short-circuit' forming a cyclo-propane 3-membered ring. It is thus a highly strained molecule. It is thought to be only mildly hazardous, causing skin irritation or dermatitis and allergic skin reactions. It contributes to the aroma of Juniper.
Copaene has a similar short-circuit, but one between the two rings, this time forming a cyclo-butane 4-membered ring structure. It is an oily liquid found in the essential oil of several plants, its name deriving from the tropical
Copalba (Copalfera langsdorfii) resin-producing tree. α-Copaene strongly attracts the Mediterranean Fruit fly Ceratitis capitata, a major pest of fruit orchards the World over, it is therefore used commercially to ensnare them before subsequent elimination.
Germacrenes A, B, C and D are volatile sesquiterpenes with aromas synthesized by many plants for their insecticidal and anti-bacterial properties. They also play a role in insect pheromones. Germacrene D is present in Juniper but high concentrations are present in Red Dead-Nettle (Lamium purpureum)
Bicyclogermacrene again has two double bonds but a missing bond between the two halves, so has a 10-membered ring, but with the methyl-ethane addition being bound to the main ring by a strained cyclo-propane 3-membered ring.
Cedrol has two fused cyclopentane groups fused to a cyclohexane and additional exo-cyclic methyl groups and the single hydroxy group making this an alcohol. It is present not only in Juniper but also evergreen trees belonging to the Cypress Family (Cupressaceae) and at a concentration of about 17% in Cedarwood Oil and has been detected in a relative of Oregano. It is used for its resinous aroma.
The (+)-stereoisomer of Sabinene is also present which additionally has a cyclo-propane 3-membered ring, and is hence a strained contorted molecule. It is one of the three main aroma components of Juniper Berry Oil, the others being (+)-
1-Terpinene-4-ol (aka Terpinen-4-ol) and (+)-α-Pinene which has a 4-membered cyclo-butane ring (and is therefore also strained).