Easily mistaken for : several other Burdocks such as with
Greater Burdock (Arctium lappa) and especially with
Wood Burdock (Arctium nemerosum) and the hybrid between
Greater Burdock and Lesser Burdock. Even for experts the distinction between some of the species and sub-species is less than obvious and many botanists refuse to differentiate between some of them.
Any hybrids between the very similar Lesser Burdock and
Wood Burdock are not proven.
There are two similar sub-species of Lesser Burdock:
However, most botanists refuse to try to tell those sub-species apart and instead group them under Lesser Burdock, provided of course they have positively ID'd it as Lesser Burdock.
- Arctium minus ssp. minus
- Arctium minus ssp. pubens - but this may be another (but fertile) hybrid between Great and Lesser Burdocks, in which case it should be named
Arctium × pubens
Hybridizes with :
Greater Burdock (Arctium lappa) to produce
Intermediate Burdock aka
Arctium × nothum which occurs infrequently in the South of Britain and combines the flat-topped flowers of
Greater Burdock with the hollow lower leaf stems of Lesser Burdock.
Some similarities to : Knapweeds but the leaves are arrow-shaped and the flower heads have burrs with hooks on the end.
Lesser Burdock has a greater range than does
Greater Burdock, stretching as far north as the tips of Scotland whereas
Greater Burdock is not found north of Tebay. Lesser Burdock can be found all over the UK and Ireland apart from inland mountainous areas of Scotland since it can tolerate a greater range of soils than can
Greater Burdock. Lesser Burdock grows in waysides, woods, wasteland, rough ground, beside roads and by hedges.
Greater Burdock grows taller, may have much larger leaves (especially near the base) and has larger flowers in flat-topped clusters than does Lesser Burdock, Lesser Burdock conversely has hollow basal leaf-stems. For sizes and details see photo captions.
Children pick burrs from the plants, which come away easily as whole globes in autumn. They then hurl them at their friends (and possibly into the hair of their enemies) where they stick tenaciously to hair or woolly clothes by means of the hooked burrs. If pulled off, some of the individual burrs will break free from the burr-globe and remain on clothes or in the hair, complete with seed at the bottom. This is how the plant is able to spread, although it also spreads locally by underground rhizomes. The individual burrs or whole burr globes also readily attach to passing animal fur should they brush passed the plant in autumn.
The popular drink 'Dandelion and Burdock' can be prepared with Burdock and Dandelions, but the process must be strictly controlled so as to exclude or reduce the toxins within Burdock! It is made from the long and tough underground rhizomes of the Burdock plant which extend deeply in several directions and those of Dandelion which are not as extensive. Bottles of Dandelion and Burdock in shops are seldom made from real ingredients but rather from synthetic flavourings and colourings, except for Fentimans 'Dandelion and Burdock' which contains the original ingredients and from Fitzpatrick's Temperance Bar (the only remaining temperance bar in the UK) which is located in Rawtenstall, Lancashire (lovely it is too). [Root Beer (American) is synonymous with Sarsaparilla tastes totally different and used to be made from the non-native tree (
Sassafras albidium) but that process was banned because of the carcinogenic Safrole which that contains but is now made from synthetic ingredients. Safrole has a 'sweet-shop' aroma.)
The burrs of burdock inspired the Swiss inventor George de Mestral to invent Velcro. The name 'vecro; is an amalgamation of 'velvet' (velours) with crotchets (hooks).
Burdock contains a plethora of differing secondary metabolites:
polyynes) account for between 0.1 to 0.002%. Ten other hydrocarbon polyacetylenes and their epoxides are also present.
Polysaccharides and Mucilages such as
Xyloglucan (which are huge molecules).
DiLignans such as
- Sesquiterpene Lactones
- Organic Acids: Acetic Acid,
Butyric Acid, Caffeic Acid,
IsoValeraic Acid, Linoleic Acid,
Myristic Acid, Oleic Acid, Palmitic Acid,
Propionic Acid, Stearic Acid, Tiglic Acid,
Carbohydrates (up to 50% Inulin is found within the roots, a sugar which does not invoke a diabetic response)
There are several hydrocarbon polyacetylenes (polyynes) with between 2 and 4 alternate triple-bonds produced within Greater Burdock, but the above is the most important. Some are 13-carbon (as above) whilst others are 15-carbon and 17-carbon atom polyynes. Some of their epoxides are also present where a bridging oxygen atom straddles across where a double-bond used to exist, replaced by a single bond. All are toxic phytoalexins.
There are also twelve slightly differing unusual, sulfur-containing, Propynyl BiThienyls found within Burdock. The groups which can substitute the -R are shown to the right. All are toxic to some degree.
Arctinol is the 4th Propenyl BiThienyls as shown above and may be more abundant in Burdock than the others since it has a common chemical name - being named after the Burdock genus. But then, a year after your Author wrote that last sentence, he found another 5 named derivatives, now depicted in the amended diagram above. Thus there are
Arctinon B, The observant will note there are still some lacking a common chemical name.
Lappaphen A an amalgamation of the polyyne Arctinol shown above with the sesquiterpene lactone
DeHydroCostusLactone shown below. All three compounds are found within
Greater Burdock (Arctium lappa), from which it takes its common name. Lappaphen B also occurs in Lesser Burdock, but that is just a stereoisomer of Lappaphen A on the orientation of the only -OH and un-shown H bonds.
Arctiopicrin is similar to
DehydroCostusLactone shown alongside it except for the additional moieties attached to the main ring, which has had a link removed to produce a 10-membered ring instead of 5-membered ring fused to a 7-membered ring which is DehydroCostusLactone.
These are just two of several Sesquiterpene Lactones found within Greater Burdock (and since burdocks are so similar, perhaps Lesser Burdock too). It has similarities to
Achillin and other sesquiterpene lactones.
Arctigenin is one of several
lignans found within
Greater Burdock (the fruits are rich in lignans). Lignans can form polymers. One such is
DiArctigenin, which is also found in Burdock.
Arctiin is the glycoside of Arctigenin. These particular lignans are also lactones. Burdock has long been used in the treatment of inflammatory conditions. All three are inhibitors of the production of Nitric Oxide within the human body, which eliminates the nitric oxide induced effects such as pro-inflammatory actions and vasodilation.
MISC SECONDARY METABOLITES
GuanidinoButyric Acid (aka γ-GuanidinoButyric Acid) is an acid widely distributed in nature such as edible fruits, bakers yeast, insects and higher mammals and of course Burdock. It is a plant hormone and amino acid - the N-amidino derivative of the Amino acid
Fukinone (aka Eremophil-7(11)-en-8-one)is a sesquiterpene ketone which is also found in Giant Butterbur (Petasites japonicus).
Baicalin is the glycouronide of
Baicalein, a flavone. Within the human body both compounds exhibit positive allosteric modulation of the benzodiazepan site and other receptors in the brain, exhibiting anxiolytic effects (anti-anxiety effects such as that exhibited by alcohol in the initial stages of exposure). It also has anti-inflammatory effects.
Aplotaxene is one of a number of similar unsaturated aliphatic hydrocarbons found within Burdock and some species of Thistles in both the Cirsium and Carduus genera.