LESSER BURDOCK

Arctium minus

Daisy & Dandelion Family [Asteraceae]

Flowers:
month8jul month8july month8aug month8sep month8sept

Pappus: pappusZpossible (yellow, short, inconspicuous)
pappus8sep pappus8sept pappus8oct pappus8nov pappus8dec

status
statusZnative
 
flower
flower8purple flower8mauve
 
inner
inner8green
 
morph
morph8actino
 
petals
petalsZMany
 
type
typeZglobed
 
stem
stem8round
 
stem
stem8ribbed
 
stem
stem8hollow
leaf stalk
toxicity
toxicityZmedium
 
contact
contactZlowish
 

5th July 2015, Rimrose Valley Country Pk, Sefton Coast. Photo: © RWD
A native which grows 60-130cm tall.


11th Aug 2015, arable fields, Burscough Bridge, Lancs. Photo: © RWD
All alone in a field.


5th July 2015, Rimrose Valley Country Pk, Sefton Coast. Photo: © RWD
Branches alternate on the stem. The size of the leaves varies; smaller near the top of the plant or the extremities of the branch and larger towards the bottom or near the main stem. [To the right is the un-related purple-flowered Hemp-agrimony (Eupatorium cannabinum)]


5th July 2015, Rimrose Valley Country Pk, Sefton Coast. Photo: © RWD
Stem reddish-brown (or greenish), with many small ridges, the ridges having very short white hairs.


5th July 2015, Rimrose Valley Country Pk, Sefton Coast. Photo: © RWD
Branches have flowers near the extremities of smaller branch.


5th July 2015, Rimrose Valley Country Pk, Sefton Coast. Photo: © RWD
On Lesser Burdock the flowers are clustered together on short (typically 0 to 2cm or more) flower stalks whereas on Greater Burdock they are much longer at 2.5cm or longer (on terminal flowers in main clusters) and the cluster are flat-topped on Greater Burdock.


5th July 2015, Rimrose Valley Country Pk, Sefton Coast. Photo: © RWD
The flower clusters have their flower-heads at various levels (whereas on Greater Burdock they are in flat-topped clusters).


5th July 2015, Rimrose Valley Country Pk, Sefton Coast. Photo: © RWD
Typical shape of upper leaf.


5th July 2015, Rimrose Valley Country Pk, Sefton Coast. Photo: © RWD
The flowers will eventually be nearly globed with green bracts (actually phyllaries) radiating out and a tuft of many purple florets slightly sticking proud of the apex. The flowers of Lesser Burdock are on overall average smaller (at 15-32mm across) than those of Greater Burdock (at 27-40mm across on average).


5th July 2015, Rimrose Valley Country Pk, Sefton Coast. Photo: © RWD
The bracts around the flower are thin and taper to a wire with burred tip (the curled-over tip catches on fur to be carried wherever the animal goes and to later fall off and with it the fatter seed which each bract carries at its base).


5th July 2015, Rimrose Valley Country Pk, Sefton Coast. Photo: © RWD
The hooked burrs are all the better to latch on to fur, hair and clothing to be carried far before getting dropped to perchance take seed.


15th July 2009, Martin Mere, Burscough Bridge, Lancs. Photo: © RWD
Some flowers are white, others are red, or purple or pink.


10th Aug 2012, Tideswill, White Peaks, Derbyshire. Photo: © RWD
Some flowers are lilac. The white styles which project above the flower are split into two at the end and curled over abruptly similar to the way the burs are curled over.


10th Aug 2012, Tideswill, White Peaks, Derbyshire. Photo: © RWD
The white styles.


10th Aug 2012, Tideswill, White Peaks, Derbyshire. Photo: © RWD
Each floret is a disc-floret. There are no ray-florets on Burdock flowers.


11th Aug 2015, arable fields, Burscough Bridge, Lancs. Photo: © RWD
The burrs have reddened by autumn and are now ripe.


15th July 2009, Martin Mere, Burscough Bridge, Lancs. Photo: © RWD
The burrs are abruptly and sharply hooked at the end. Some burrs have a network of white threads between neighbouring burrs.


5th July 2015, Rimrose Valley Country Pk, Sefton Coast. Photo: © RWD
Leaves in slightly-elongated Ace-of-Spades shapes. Basal leaves are larger but not nearly as large as the largest of Greater Burdock. Unlike those of Greater Burdock, the lower leaf-stalks are hollow on Lesser Burdock.


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:

  • 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
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.

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.

Whereas 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 which 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:

  • Sulfur-containing polyacetylenes (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).
  • Podophyllin-type Lignans and DiLignans such as Arctigenin
  • Sesquiterpene Lactones
  • Organic Acids: Acetic Acid, Butyric Acid, Caffeic Acid, Chlorogenic Acid, IsoValeraic Acid, Linoleic Acid, Linolenic Acid, Myristic Acid, Oleic Acid, Palmitic Acid, Propionic Acid, Stearic Acid, Tiglic Acid,
  • Aldehydes
  • Phytosterols
  • Carbohydrates (up to 50% Inulin is found within the roots, a sugar which does not invoke a diabetic response)

POLYYNES (POLYACETYLENES)

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 Arctinol A, Arctinol B, Arctinal, Arctinol, Arctinon A, 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.

SESQUITERPENE LACTONES


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


4-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 Glycine.



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.


  Arctium minus  ⇐ Global Aspect ⇒ Asteraceae  

Distribution
 family8Daisy & Dandelion family8Asteraceae

 BSBI maps
genus8Arctium
Arctium
(Burdocks)

LESSER BURDOCK

Arctium minus

Daisy & Dandelion Family [Asteraceae]