Easily mistaken for :
Garden Honeysuckle (Lonicera × italica), a hybrid between
Perfoliate Honeysuckle (Lonicera caprifolium) and
Etruscan Honeysuckle Lonicera etrusca, which is also perfoliate (the two opposite leaves totally encircle their stem) and appears not to have any existence in the UK apart from perhaps in gardens.
Easily mis-identified as :
Garden Honeysuckle (Lonicera × italica), and indeed, the Author is not 100% sure that he has not.
Related to : Himalayan Honeysuckle (Leycesteria formosa) [a plant with similar name in the same family but in a differing Genus, Leycestaria].
In the daytime the flowers have hardly any fragrance but this changes in the evening when they emanate a strong floral essence to attract the Sphinx Moth (Sphingidae) which hovers whilst drinking the nectar whilst at the same time pollinating the flowers.
The essential oil of Honeysuckle contains Eugenol, Vanillin the terpenes Ocimene and Linalool, the sesquiterpenes α-Farnesene, Germacrene D, and the Jasmonoid compounds (-)-Methyl Jasmonate, (+)-epi-Methyl Jasmonate, Jasmone, and (-)-
These jasmonoids make important contributions to the high fragrance of Honeysuckle.
(-)-Methyl Jasmonate and (+)-epi-Methyl Jasmonate are stereoisomers of each other and are air-borne signalling molecules and plant auxins (see Jasmonate Plant Hormones).
Jasmone has both the odour of
Jasmine flowers and occurs in them, produced in the metabolism of Jasmonates. It can exist in two stereoisomers , cis-Jasmone and trans-Jasmone, but in nature exists as just the cis-steroisomer. It is used in cosmetics and perfumes. It has the ability to attract certain insects whilst repelling others.
Jasmin Lactone (aka (Z)-2-Pentenylpentan-5-olide or Z-Dec-7-en-5-olide ) is also used as a flavouring compound and as a fragrance with a sweet and warm odour. It's optical antipode ((+)-(S)--(Z)-Dec-7-en-5-olide) occurs in
Tuberose (Polianthes tuberosa) flowers which are native to Mexico. Note that both oxygen atoms have been re-arranged in comparison to the other three Jasmonoids. Methyl Jasmone and Jasmin Lactone also occur in Ceylon Tea (Sri Lankan Tea).