Arctium lappa – Burdock pappus bristles can cause skin
irritation and burdock ophthalmia
Contact with and handling of burs (the flowering heads or infructescences) from the
greater burdock (Arctium lappa L., Asteraceae) and other members of the same genus, is a
potential hazard for humans, horses, and dogs. The minute, sharply-pointed, bristly
pappus hairs easily detach from the top of the 'seeds' and are carried by the slightest
breeze – attaching to skin, mucous membranes, and eyes where they can cause severe
dermal irritation, possible respiratory manifestations, and ophthalmia.
PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.1871v1 | CC-BY 4.0 Open Access | rec: 17 Mar 2016, publ: 17 Mar 2016
Arctiumlappa–Burdockpappusbristlescancauseskin
irritationandburdockophthalmia
TheodorC.H.Cole1,*,ShanSu1,2,andHartmutH.Hilger3
Contactwithandhandlingofburs(thefloweringheadsorinfructescences)fromthe
greaterburdock(ArctiumlappaL.,Asteraceae)andothermembersofthesamegenus,
isapotentialhazardforhumans,horses,anddogs.Theminute,sharply-pointed
pappushairseasilydetachfromthetopofthe'seeds'andarecarriedbytheslightest
breeze–attachingtoskin,mucousmembranes,andeyeswheretheycancausesevere
dermalirritation,possiblerespiratorymanifestations,andophthalmia.
Burdockisawidespreadruderalweedthroughoutthenortherntemperatezone.
BurdockrootiscommonlyeateninJapan(
"gobo"),China(
"niúbàng"),and
Korea(
"ueong")andextensivelygrownandcultivatedthere.Today,inthesecountries,
shreddedfreeze-driedburdockrootispopularlyeateninsoupsandmanyotherdishes.
MostmembersofthetribeCardueaeinAsteraceaebeararingofmoreorlessbarbed
pappushairsorbristlesatthetopofthedeveloping'seeds'.Theseseemtoservethe
purposeofdefenseagainstpossibleintrudinginsects(plant-feedingbugsasbyour
observation)probingfromthetopoftheburtowardstheseeds.
Inthecourseofcollectinglargeramountsofburdock'seeds'(actually:single-seededfruits
calledachenes,originatingfrommanyflowerssurroundedbyinvolucralleaves)fora
researchproject,webecameafflictedwithadiscomfortingskinandeyeirritationwhich
noneofuscouldinitiallyattributetoanyassociatedagent.Apossiblesuspectcouldhave
beenchiggers(harvestmitelarvaeoftheTrombiculidae).However,inremovingtheseeds
fromthedriedburswenoticedlargeamountsofminuteyellow'chaff'thatseparatedinthe
seed-extractionandsiftingprocess.Thisfinematerialhadanoticeableaggregatingproperty
whichdidnotseemtobeduetoanygummyorresinoussubstance.Westartedtobecome
curiousaboutthemorphologyandmicroscopicallyinvestigatedtheassociatedstructures.
Afirstsimplelightmicroscopicpreparationrevealedthebarbednatureofthesestructures,
laterconfirmedandmoreclearlyrevealedbyscanningelectronmicroscopy(Figs.1–3).
Obviouslythesepappushairsweretobeheldresponsiblefortheencounteredsymptoms.
Thepossiblehazardofthesepappusbristleshasvariouslybeenreportedintheliteratureas
burdockophthalmia(nodularconjunctivitis,ulcerative/non-ulcerativekeratitis)in
humans,butalsoinaveterinariancontextregardinghorsesanddogs(1–6).
Itisadvisabletostayclearfrommatureburdockplantsinthewild,torefrainfromplaying
withmatureburs,andusingaccordingprotectivegearwhencuttingorharvestingtheplants
ingardeningsettingsorintheagriculturaldomaintoavoidcontactandpotentialharmfrom
theminutebardedpappusbristlescontainedwithinmatureburs.
(1) Munk CE (1926) Injuries to the conjunctiva by spines from the common burdock. Am J Ophthalmol 9(7):507–510
(2) Miklos A (1931) Klettenconjunctivitis. Klin Wochenschr 10(33):1555
(3) Havener WH, Falls HF, McReynolds WU (1955) Burdock bur ophthalmia. AMA Arch Ophthalmol 53(2):260–263
(4) Breed FB, Kuwabara T (1966) Burdock ophthalmia. Arch Ophthalmol 75(1):16–20
(5) Pickett JP, Crisman MV, Furr MO (1993) Conjunctival foreign body (burdock pappus) induced keratitis in horses: 10 cases. J Equine Vet Sci 13(2):88–91
(6) Foster CS, Vitale AT (2013) Diagnosis and Treatment of Uveitis, 2nd edn. Jaypee, New Delhi/London
*Correspondingauthor,email:[email protected]
1HeidelbergUniversity,InstituteofPharmacyandMolecularBiotechnology(IPMB),Dept.ofBiology,INF364,69120Heidelberg,Germany
2RutgersUniversity,ErnestMarioSchoolofPharmacy,Dept.ofPharmaceutics,WilliamLevineHall,160FreilinghuysenRd.,Piscataway,NJ08854,U.S.A.
PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.1871v1 | CC-BY 4.0 Open Access | rec: 17 Mar 2016, publ: 17 Mar 2016
3FreieUniversitätBerlin,InstituteofBiology,PlantMorphologyandSystematics,Altensteinstr.6,14195Berlin,Germany
Fig.1
TCHCole
Fig.2
PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.1871v1 | CC-BY 4.0 Open Access | rec: 17 Mar 2016, publ: 17 Mar 2016
Fig.3
HHHilger,FUBerlin
PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.1871v1 | CC-BY 4.0 Open Access | rec: 17 Mar 2016, publ: 17 Mar 2016
Fig.5
Fig.4
TCHCole
HHHilger,FUBerlin
Fig.6
PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.1871v1 | CC-BY 4.0 Open Access | rec: 17 Mar 2016, publ: 17 Mar 2016
TCHCole
Fig.7
TCHCole
Fig.8
TCHCole
Figurelegends
Fig.9
Fig.1.LMofbarbedpappusbristles
Fig.2.SEMofpappusbristles
Fig.3.LongisectionoffruitingArctiumhead;
redarrowpointstopappusbristles;incurvedtips
ofinvolucralbractsactas"velcro"hooks
Fig.4.Bulldozeredentire,matureplants
incl.taproots
Fig.5.Bloomingplantwithimmatureburs
Fig.6.Freshlycutfruitingheads
(redarrowindicateschaffypappushairs)
Figs.7&8.Driedfloweringheads
(redarrowspointtoaggregationsofpappal
bristles;bluearrowpointstothecrownofpappus
PeerJ Preprintsbristlesstillattachedontopofasingleachene)
| https://doi.org/10.7287/peerj.preprints.1871v1 | CC-BY 4.0 Open Access | rec: 17 Mar 2016, publ: 17 Mar 2016
TCHCole
Fig.9.Siftedburdock"seeds"(about2kg)