Editing Doctrine of signatures (section)

== Linked remedies ==
{| class="wikitable"
|+
!Name
!Link to doctrine
!History of use
!Effectiveness
|-
|[[Scrophularia nodosa|Common figwort]] ([[Scrophulariaceae]])<ref name=":13">{{Cite journal |last1=Blanco-Salas |first1=José |last2=Hortigón-Vinagre |first2=María P. |last3=Morales-Jadán |first3=Diana |last4=Ruiz-Téllez |first4=Trinidad |date=2021-07-02 |title=Searching for Scientific Explanations for the Uses of Spanish Folk Medicine: A Review on the Case of Mullein (Verbascum, Scrophulariaceae) |journal=Biology |language=en |volume=10 |issue=7 |pages=618 |doi=10.3390/biology10070618 |doi-access=free |pmid=34356473 |pmc=8301161 |issn=2079-7737 }}</ref> [[File:Scrophularia capillaris.jpg|center|thumb|242x242px|Sample of ''Scrophularia capillaris'' and root structure]]
|Figwort's roots have small nodules that resemble nodes within the lymph system or swelling.<ref name=":13" />
|Used in Spain to treat hemorrhoids, digestive conditions, respiratory conditions, and skin conditions.<ref name=":132">{{Cite journal |last1=Blanco-Salas |first1=José |last2=Hortigón-Vinagre |first2=María P. |last3=Morales-Jadán |first3=Diana |last4=Ruiz-Téllez |first4=Trinidad |date=2021-07-02 |title=Searching for Scientific Explanations for the Uses of Spanish Folk Medicine: A Review on the Case of Mullein (Verbascum, Scrophulariaceae) |journal=Biology |language=en |volume=10 |issue=7 |pages=618 |doi=10.3390/biology10070618 |doi-access=free |pmid=34356473 |pmc=8301161 |issn=2079-7737 }}</ref> In ancient China, ''[[Scrophularia ningpoensis]]'', another member of the Scrophulariaceae family, was used for sore throats, abscesses, carbuncles, and constipation.<ref>{{Cite journal |last1=Ren |first1=Dan |last2=Shen |first2=Zhan-yun |last3=Qin |first3=Lu-ping |last4=Zhu |first4=Bo |date=2021-04-06 |title=Pharmacology, phytochemistry, and traditional uses of Scrophularia ningpoensis Hemsl |url=https://linkinghub.elsevier.com/retrieve/pii/S0378874120335765 |journal=Journal of Ethnopharmacology |volume=269 |pages=113688 |doi=10.1016/j.jep.2020.113688 |pmid=33338592 |issn=0378-8741|url-access=subscription }}</ref> Native American women in the Shenandoah Valley would use this plant after childbirth to prevent bleeding and cramps or as a calming tonic.<ref>{{Cite book |last1=Simpson |first1=Ann |url=https://books.google.com/books?id=tChfEAAAQBAJ&dq=Scrophulariaceae+doctrine&pg=PP1 |title=Wildflowers of Shenandoah National Park: A Field Guide to the Park's Wildflowers |last2=Simpson |first2=Rob |date=2022-07-01 |publisher=Rowman & Littlefield |isbn=978-1-4930-6031-3 |language=en}}</ref> The treatment linked to the doctrine of signs was for inflammation and conditions that cause lymph node swelling, which are thought to resemble the root nodules.<ref>{{Cite book |last=Graves |first=Julia |url=https://books.google.com/books?id=8ybT6QU1l3gC&q=figwort&pg=PT12 |title=The Language of Plants: A Guide to the Doctrine of Signatures |date=2012 |publisher=Steiner Books |isbn=978-1-58420-103-8 |language=en}}</ref>
|Study of this plant has correlated it with anti-inflammatory effects.<ref name=":133">{{Cite journal |last1=Blanco-Salas |first1=José |last2=Hortigón-Vinagre |first2=María P. |last3=Morales-Jadán |first3=Diana |last4=Ruiz-Téllez |first4=Trinidad |date=2021-07-02 |title=Searching for Scientific Explanations for the Uses of Spanish Folk Medicine: A Review on the Case of Mullein (Verbascum, Scrophulariaceae) |journal=Biology |language=en |volume=10 |issue=7 |pages=618 |doi=10.3390/biology10070618 |doi-access=free |pmid=34356473 |pmc=8301161 |issn=2079-7737 }}</ref> This is potentially linked to the fact that this species has [[iridoid]]s, which can exhibit anti-inflammatory and antioxidant properties.<ref>{{Cite journal |last1=Thabet |first1=Amany A. |last2=Ayoub |first2=Iriny M. |last3=Youssef |first3=Fadia S. |last4=Al-Sayed |first4=Eman |last5=Efferth |first5=Thomas |last6=Singab |first6=Abdel Nasser B. |date=2022-08-01 |title=Phytochemistry, structural diversity, biological activities and pharmacokinetics of iridoids isolated from various genera of the family Scrophulariaceae Juss. |journal=Phytomedicine Plus |volume=2 |issue=3 |pages=100287 |doi=10.1016/j.phyplu.2022.100287 |issn=2667-0313|doi-access=free }}</ref>
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|[[Euphrasia|Eyebright]] aka Euphrasy/Euphrasia (''[[Euphrasia rostkoviana]]'')<ref name="ScienceMus2">{{cite web |title=Doctrine of Signatures |url=http://www.sciencemuseum.org.uk/broughttolife/techniques/doctrine.aspx |url-status=dead |archive-url=https://web.archive.org/web/20140103201719/http://www.sciencemuseum.org.uk/broughttolife/techniques/doctrine.aspx |archive-date=January 3, 2014 |access-date=February 8, 2014 |publisher=Science Museum}}</ref> [[File:Euphrasia stricta kz10.jpg|center|thumb|226x226px|Euphrasia flower]]
|Named "eyebright" because its flower blossoms resemble eyes.<ref name="ScienceMus2" />
|Used in medieval Europe to treat conditions that have to do with irritated or swollen eyes, like cataracts or conjunctivitis. They also were used for digestive conditions, jaundice, diabetes, and respiratory conditions. Some of these treatments are not eye-related and thus do not reflect the doctrine.<ref name=":32">{{Cite journal |last1=Gruľová |first1=Daniela |last2=De Feo |first2=Vincenzo |date=2017 |title=Euphrasia Rostkoviana Hayne Active Components and Biological Activity for the Treatment of Eye Disorders |url=https://www.researchgate.net/publication/320102226 |journal=Scientific Bulletin of the Uzhhorod University |via=Research Gate}}</ref>
|Contains [[flavonoid]]s and [[polyphenol]]s, which have been linked to lowered inflammation by interacting with [[cytokine]]s.<ref name=":32" /> Extracts of the plant have successfully shown antibacterial properties, specifically with [[gram-positive bacteria]]. It is still used and effective within [[conjunctivitis]]<ref name=":32" /> and [[blepharitis]]<ref name=":32" /> treatments through eye drops.
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|Swallowwort ([[Papaveraceae]])<ref>{{Cite book |last=Wood |first=Matthew |url=https://books.google.com/books?id=Czw-DwAAQBAJ&dq=Chelidonium+%22doctrine+of+signatures%22&pg=PR9 |title=The Book of Herbal Wisdom: Using Plants as Medicines |date=2017-12-19 |publisher=North Atlantic Books |isbn=978-1-62317-124-7 |language=en}}</ref> [[File:Chelidonium majus 4 RF.jpg|center|thumb|Swallowwort plant|208x208px]]
|Linked through animal behavior, "some say that this [the name] was because it flowered at about the time the swallows reappeared and finished when they left; but there grew a story that swallow mothers bathed their blind nestlings with its [figwort's] juices to help them see."<ref>{{Cite book |last=Hart-Davies |first=Christina |url=https://books.google.com/books?id=dxf7EAAAQBAJ&q=nestling&pg=PP1 |title=The Herbal Year: Folklore, History and Remedies |date=2024-04-02 |publisher=Yale University Press |isbn=978-0-300-26586-6 |language=en}}</ref><ref>{{Cite book |last=Leyel |first=C. F. |url=https://books.google.com/books?id=8kz6q3Alkm4C&q=swallow&pg=PA11 |title=Cinquefoil |date=2007 |publisher=Health Research Books |isbn=978-0-7873-1413-2 |language=en}}</ref><ref>{{Cite book |last=Richardson |first=Rosamond |url=https://books.google.com/books?id=sFAmEAAAQBAJ&q=swallowwort&pg=PT4 |title=Britain's Wild Flowers: A Treasury of Traditions, Superstitions, Remedies and Literature |date=2017-04-13 |publisher=National Trust |isbn=978-1-911358-34-3 |language=en}}</ref> Swallowwort may also be referred to as celandine (species ''[[Chelidonium majus]]'' in the family Papaveraceae), and this is cited as being linked to the doctrine because of the yellow latex believed to link with jaundice and liver bile.<ref>{{Cite book |last=Wood |first=Matthew |url=https://books.google.com/books?id=Czw-DwAAQBAJ&dq=Chelidonium+%22doctrine+of+signatures%22&pg=PR9 |title=The Book of Herbal Wisdom: Using Plants as Medicines |date=2017-12-19 |publisher=North Atlantic Books |isbn=978-1-62317-124-7 |language=en}}</ref>
|In traditional Chinese medicine, this plant was used for the treatment of jaundice, accumulation of fluids, or clots. In other regions it was used for ulcers, liver conditions, digestive complaints,<ref name=":52">{{Cite journal |last1=Pantano |first1=Flaminia |last2=Mannocchi |first2=Giulio |last3=Marinelli |first3=Enrico |last4=Gentili |first4=S. |last5=Graziano |first5=Silvia |last6=Busardò |first6=F. P. |last7=Di Luca |first7=Natale Mario |date=2017 |title=Hepatotoxicity induced by greater celandine (Chelidonium majus L.): a review of the literature |url=https://iris.uniroma1.it/handle/11573/968547 |journal=European Review for Medical and Pharmacological Sciences |volume=21 |issue=1 |pages=46–52}}</ref> oral infections, tuberculosis, and dermatological conditions.<ref name=":42">{{Cite journal |last1=Kwon |first1=Haejin |last2=Sathasivam |first2=Ramaraj |last3=Yoon |first3=Jiwon |last4=Park |first4=Chanung |last5=Park |first5=Nam Il |last6=Chung |first6=Yong Suk |last7=Park |first7=Sang Un |date=2024-03-01 |title=Expression Analysis of Phenylpropanoid Pathway Genes and Phenylpropanoid Accumulation in Different Organs of Chelidonium majus L. |journal=Natural Product Communications |language=EN |volume=19 |issue=3 |pages=  |doi=10.1177/1934578X241239835 |issn=1934-578X|doi-access=free }}</ref>
|"[[Isoquinoline alkaloids]], flavonoids, [[carotenoid]]s, [[saponin]]s, organic acids, and vitamins A and C are the distinct biologically active compounds of ''C. majus''. According to the metabolites identified, it has been found to possess a range of pharmacological effects such as antimicrobial activity, anti-inflammatory, analgesic, natriuretic, antidiuretic, and anticancer effects."<ref name=":42" /> The plant has been linked with [[hepatotoxicity]]. Due to the cause of this side effect being under investigation, medicinal use in high or consistent doses is unusual due to potential health effects.<ref name=":52" />
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|Birthwort (''[[Aristolochia clematitis]]'')<ref name=":03">{{Cite journal |last=Durant |first=Owen |date=2017-12-01 |title=Cataloguing nature's 'library': The doctrine of signatures in Western thought and practice |url=https://www.ingentaconnect.com/content/bshp/ph/2017/00000047/00000004/art00004 |journal=Pharmaceutical Historian |volume=47 |issue=4 |pages=95–98}}</ref> [[File:Aristolochia clematitis 002.JPG|center|thumb|184x184px|''Aristolochia clematitis'']]
|Said to resemble the womb and birth canal in shape and believed to provide a good birth.<ref name=":03" />
|Utilized in India, Greece, and China to induce menstruation ([[emmenagogue]]s), induce labor, abortive measures, contraception, fever reduction ([[febrifuge]]), bladder stones, edemas, and gout.<ref name=":6">{{Cite journal |last1=Scarborough |first1=John |last2=Fernandes |first2=Andrea |date=2011 |title=Ancient Medicinal Use of Aristolochia: Birthwort's Tradition and Toxicity |url=https://www.jstor.org/stable/23645794 |journal=Pharmacy in History |volume=53 |issue=1 |pages=3–21 |jstor=23645794 |pmid=22702021 |issn=0031-7047}}</ref> It was also combined with quicklime and used as fish poison.<ref name=":6" />
|This plant has been linked with [[aristolochic acid]] [[Kidney disease|nephropathy]], which can cause [https://www.thoracic.org/education-center/ild/pdf/2020_ats_pf-ild_v13_web.pdf progressive interstitial fibrosis]—a lung disease—and bladder, kidney, or urethral cancers.<ref>{{Citation |last1=Nortier |first1=Joëlle L. |title=Aristolochic Acid Nephropathy and Balkan Nephropathy |date=2022 |work=Tubulointerstitial Nephritis |pages=207–216 |editor-last=Atta |editor-first=Mohamed G. |url=https://link.springer.com/chapter/10.1007/978-3-030-93438-5_16 |access-date=2025-04-18 |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-030-93438-5_16 |isbn=978-3-030-93438-5 |last2=Vanherweghem |first2=Jean-Louis |last3=Jelakovic |first3=Bojan |editor2-last=Perazella |editor2-first=Mark A.|url-access=subscription }}</ref> Specifically, it is linked to urothelial neoplasms, a precancerous cell in the urinary system.<ref>{{Citation |last1=Stegelmeier |first1=Bryan L. |title=Chapter 7 - Poisonous Plants |date=2023-01-01 |work=Haschek and Rousseaux' s Handbook of Toxicologic Pathology (Fourth Edition) |pages=489–546 |editor-last=Haschek |editor-first=Wanda M. |url=https://linkinghub.elsevier.com/retrieve/pii/B9780443161537000071 |access-date=2025-04-21 |publisher=Academic Press |doi=10.1016/b978-0-443-16153-7.00007-1 |isbn=978-0-443-16153-7 |last2=Davis |first2=T. Zane |editor2-last=Rousseaux |editor2-first=Colin G. |editor3-last=Wallig |editor3-first=Matthew A. |editor4-last=Bolon |editor4-first=Brad|url-access=subscription }}</ref>
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|[[Hedge woundwort]] (''Stachys sylvatica'')<ref>{{cite web |author=McDougal, Kevin |date=2013 |title=Hedge Woundwort |url=http://www.incredible-edible-todmorden.co.uk/apothecary/hedge-woundwort |url-status=dead |archive-url=https://web.archive.org/web/20131215110138/http://www.incredible-edible-todmorden.co.uk/apothecary/hedge-woundwort |archive-date=December 15, 2013 |access-date=February 8, 2014}}</ref> [[File:Stachys sylvatica 3 RF.jpg|center|thumb|''Stachys sylvatica'']]
|Believed to treat wounds and bruises because the plants themselves have holes in the leaves.<ref>{{Cite journal |last=Bagli |first=Marco |date=2021 |title=Wort Plant Names in Contemporary English |url=https://ricerca.unistrapg.it/handle/20.500.12071/45068?mode=simple |journal=Iperstoria |issn=2281-4582}}</ref><ref name=":7">{{Cite book |last=Hughes |first=Jon G. |url=https://books.google.com/books?id=GolgEAAAQBAJ&dq=woundwort+%22doctrine+of%22&pg=PT4 |title=Witches, Druids, and Sin Eaters: The Common Magic of the Cunning Folk of the Welsh Marches |date=2022-09-20 |publisher=Simon and Schuster |isbn=978-1-64411-429-2 |language=en}}</ref>
|During the medieval period, flowers were ground, mixed with salt, and used on spear and sword wounds.<ref>{{Cite book |last=Barnes |first=Simon |url=https://books.google.com/books?id=TZxZEAAAQBAJ&dq=woundwort+%22doctrine+of%22&pg=PT3 |title=The History of the World in 100 Plants |date=2022-10-27 |publisher=Simon and Schuster |isbn=978-1-3985-0549-0 |language=en}}</ref><ref>{{Cite book |last=Brown |first=Michael |url=https://books.google.com/books?id=ZWuEEAAAQBAJ&q=woad |title=Medieval Plants and their Uses |date=2022-12-02 |publisher=White Owl |isbn=978-1-5267-9459-8 |language=en}}</ref>
|Both the flower and leaf extract show antibacterial and antioxidant attributes, which help to control [[oxidative stress]] and risk of infection in healing.<ref>{{Cite journal |last1=Ouerfelli |first1=Manel |last2=Majdoub |first2=Nesrine |last3=Aroussi |first3=Jihen |last4=Almajano |first4=María Pilar |last5=Bettaieb Ben Kaâb |first5=Leila |date=2021-09-01 |title=Phytochemical screening and evaluation of the antioxidant and anti-bacterial activity of Woundwort (Anthyllis vulneraria L.) |url=https://link.springer.com/article/10.1007/s40415-021-00736-6 |journal=Brazilian Journal of Botany |language=en |volume=44 |issue=3 |pages=549–559 |doi=10.1007/s40415-021-00736-6 |bibcode=2021BrJBo..44..549O |issn=1806-9959|hdl=2117/356661 |hdl-access=free }}</ref>
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|Liverwort ([[Marchantiophyta]] or ''[[Hepatica]]'')<ref name=":8">{{Cite book |last=Wilbraham |first=Joanna |url=https://books.google.com/books?id=zfRGEQAAQBAJ&dq=liverwort+%22doctrine+of%22&pg=PP1 |title=Mosses, Liverworts, and Hornworts of the World: A Guide to Every Order |date=2025-08-05 |publisher=Princeton University Press |isbn=978-0-691-26877-4 |language=en}}</ref> [[File:Illustration.Hepatica nobilis.jpg|center|thumb|Illustration of Hepatica plant|268x268px]]
|The mat-forming liverworts resembled lobes of the liver.<ref name=":8" />
|"Antimicrobial, antifungal, antipyretic, antidotal activity; used to cure cuts, burns, scalds, fractures, swollen tissue, poisonous snake bites and gallstones".<ref>{{Cite journal |last1=Jacek |first1=Drobnik |last2=Adam |first2=Stebel |date=2021 |title=Four Centuries of Medicinal Mosses and Liverworts in European Ethnopharmacy and Scientific Pharmacy: A Review |url=https://www.mdpi.com/2223-7747/10/7/1296 |journal=Plants |language=en |volume=10 |issue=7 |doi=10.3390/plant |doi-broken-date=25 April 2025 |doi-access=free |issn=2223-7747 |archive-url=http://web.archive.org/web/20250207003405/https://www.mdpi.com/2223-7747/10/7/1296 |archive-date=2025-02-07}}</ref>
|There is some scientific support for specific species having properties that can aid treatment of hepatitis, blisters, gastrointestinal complaints, and fever. This is linked to antibacterial and antifungal properties. Liverworts also have metabolites that interact with the central nervous system and thus can have serious side effects.<ref>{{Cite journal |last1=Bandyopadhyay |first1=Anustup |last2=Dey |first2=Abhijit |date=2022-05-01 |title=The ethno-medicinal and pharmaceutical attributes of Bryophytes: A review |journal=Phytomedicine Plus |volume=2 |issue=2 |pages=100255 |doi=10.1016/j.phyplu.2022.100255 |issn=2667-0313|doi-access=free }}</ref>
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|[[Lungwort]] (''Pulmonaria officinalis'')<ref name=":03" /><ref name="Birmingham">{{cite web |title=The Tudors |url=http://www.birminghambotanicalgardens.org.uk/wp-content/uploads/2009/10/tudors.pdf |url-status=usurped |archive-url=http://web.archive.org/web/20210904213217/http://www.birminghambotanicalgardens.org.uk/wp-content/uploads/2009/10/tudors.pdf |archive-date=4 September 2021 |access-date=11 November 2014 |publisher=Birmingham Botanical Gardens}}</ref> [[File:Pulmonaria officinalis 800.jpg|center|thumb|192x192px|Lungwort plant]]
|The spotted leaves resemble structures within the lungs.{{cn|date=April 2025}}
|Was used in Europe to treat [[Phthisis pulmonalis|phthisis]], another name for tuberculosis.<ref>{{Cite journal |date=1873 |title=The Doctrine Of Signatures |url=https://www.jstor.org/stable/25233757 |journal=The British Medical Journal |volume=1 |issue=627 |pages=19 |jstor=25233757 |issn=0007-1447}}</ref>
|Within a 2022 systematic review of scientific research, Chauhan and associates concluded that "safety studies and clinical trials are missing for lungworts to establish most of their potential biological properties."<ref>{{Cite journal |last1=Chauhan |first1=Shweta |last2=Jaiswal |first2=Varun |last3=Cho |first3=Yeong-Im |last4=Lee |first4=Hae-Jeung |date=2022-07-01 |title=Biological Activities and Phytochemicals of Lungworts (Genus Pulmonaria) Focusing on Pulmonaria officinalis |journal=Applied Sciences |language=en |volume=12 |issue=13 |pages=6678 |doi=10.3390/app12136678 |doi-access=free |issn=2076-3417}}</ref>
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|[[Spleenwort]] (''Asplenium'')<ref>{{cite book |last1=Irvine |first1=Alexander |url=https://books.google.com/books?id=u8cgAQAAMAAJ |title=The Phytologist: A Botanical Journal, Volume 4 |date=1860 |publisher=William Pamplin |page=308 |quote=As late as 1657 we find William Coles, who was a herbarist ... speaking of Spleenwort, or Miltwort, tells us that the learned Crollius, amongst the signatures of parts, doth set down Ceterach to have the signature of the spleen, and that therefore it is profitable for all diseases thereof;}}</ref> [[File:Asplenium viride RF.jpg|center|thumb|177x177px|''Spleenwort'' plant]]
|The grass is said to resemble both hair and worms and is used to treat worms or hair loss.<ref name=":9">{{Cite book |url=https://doi.org/10.52305/zdnj1623 |title=Ferns: Growth, Diversity and Ecological Importance |date=2023 |publisher=Nova Science Publishers |doi=10.52305/zdnj1623 |isbn=979-8-88697-554-3 |editor-last=Kumar Srivastava |editor-first=Shobhit |editor-last2=Prakash Srivastava |editor-first2=Gyan}}</ref>
|Usually ingested as a tea used to relieve stomach issues and parasitic worm infections in both Europe and China.<ref name=":9" /><ref>{{Citation |last1=Ye |first1=Huagu |title=Medicinal Ferns of Parkeriaceae, Athyriaceae, Thelypteridaceae, Aspleniaceae, Blechnaceae, Dryopteridaceae, and Davalliaceae |date=2021 |work=Common Chinese Materia Medica: Volume 1 |pages=93–125 |editor-last=Ye |editor-first=Huagu |url=https://link.springer.com/chapter/10.1007/978-981-16-2062-1_6 |access-date=2025-04-21 |place=Singapore |publisher=Springer Nature |language=en |doi=10.1007/978-981-16-2062-1_6 |isbn=978-981-16-2062-1 |last2=Li |first2=Chuyuan |last3=Ye |first3=Wencai |last4=Zeng |first4=Feiyan |last5=Liu |first5=Fangfang |last6=Wang |first6=Faguo |last7=Ye |first7=Yushi |last8=Fu |first8=Lin |last9=Li |first9=Jianrong |editor2-last=Li |editor2-first=Chuyuan |editor3-last=Ye |editor3-first=Wencai |editor4-last=Zeng |editor4-first=Feiyan|url-access=subscription }}</ref>
|As of 2021, systematic reviews of different medicinal applications showed no scientific consensus that they are effective in treating any conditions.<ref>{{Cite journal |last1=Flores-González |first1=Mathias |last2=Simirgiotis |first2=Mario |last3=Torres-Benítez |first3=Alfredo |date=2021-07-14 |title=Systematic Review: Antioxidant and Neuroprotective Capacity of Species of the Genus Asplenium (Monilophyta: Aspleniaceae) |url=https://www.mdpi.com/2673-9992/8/1/14 |journal=Plants |language=en |publisher=MDPI |pages=14 |doi=10.3390/IECBS2021-10665|doi-access=free }}</ref><ref>{{Cite journal |last1=Petkov |first1=Venelin |last2=Batsalova |first2=Tsvetelina |last3=Stoyanov |first3=Plamen |last4=Mladenova |first4=Tsvetelina |last5=Kolchakova |first5=Desislava |last6=Argirova |first6=Mariana |last7=Raycheva |first7=Tsvetanka |last8=Dzhambazov |first8=Balik |date=2021-05-25 |title=Selective Anticancer Properties, Proapoptotic and Antibacterial Potential of Three Asplenium Species |journal=Plants |language=en |volume=10 |issue=6 |pages=1053 |doi=10.3390/plants10061053 |doi-access=free |issn=2223-7747 |pmc=8225096 |pmid=34070269|bibcode=2021Plnts..10.1053P }}</ref>
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|[[Walnut]]s (Juglans)<ref name=":7" /><ref>{{Cite journal |last=Bennett |first=Bradley C. |date=2007-09-01 |title=Doctrine of Signatures: An explanation of medicinal plant discovery or Dissemination of knowledge? |url=https://link.springer.com/article/10.1663/0013-0001(2007)61%5B246:DOSAEO%5D2.0.CO;2 |journal=Economic Botany |language=en |volume=61 |issue=3 |pages=246–255 |doi=10.1663/0013-0001(2007)61[246:DOSAEO]2.0.CO;2 |issn=1874-9364|url-access=subscription }}</ref> [[File:Walnuts - whole and open with halved kernel.jpg|center|thumb|200x200px|Walnut nut and shell]]
|Believed to treat brain-related conditions because the seed resembles a brain or gastrointestinal complaints because of the appearance of the intestines.<ref name=":7" />
|Used to treat headaches.<ref>{{Cite journal |last=Marabini |first=Camilla |date=2024-12-10 |title=Food in Shakespeare: a Study of Culinary References in the Bard's Plays |url=https://unitesi.unive.it/handle/20.500.14247/15246 |journal=Ca'Foscari University of Venice}}</ref>
|Walnuts contain fatty acids, which are valuable for the brain.<ref>{{Cite journal |last1=Chauhan |first1=Abha |last2=Chauhan |first2=Ved |date=2020-02-20 |title=Beneficial Effects of Walnuts on Cognition and Brain Health |journal=Nutrients |language=en |volume=12 |issue=2 |pages=550 |doi=10.3390/nu12020550 |doi-access=free |issn=2072-6643 |pmc=7071526 |pmid=32093220}}</ref><ref>{{Cite book |last1=Mukherjee |first1=Soumya |url=https://www.taylorfrancis.com/books/9781003300502 |title=Plant-based Foods and their Implications in Brain Health |last2=Ramakrishna |first2=Akula |last3=Bhattacharjee |first3=Atanu |date=2024-11-19 |publisher=CRC Press |isbn=978-1-003-30050-2 |edition=1 |location=New York |language=en |doi=10.1201/9781003300502}}</ref> From a medicinal standpoint, there is not a significant evidence base that it can prevent cognitive decline.<ref>{{Cite journal |last1=Cahoon |first1=Danielle |last2=Shertukde |first2=Shruti P. |last3=Avendano |first3=Esther E. |last4=Tanprasertsuk |first4=Jirayu |last5=Scott |first5=Tammy M. |last6=Johnson |first6=Elizabeth J. |last7=Chung |first7=Mei |last8=Nirmala |first8=Nanguneri |date=2021-01-01 |title=Walnut intake, cognitive outcomes and risk factors: a systematic review and meta-analysis |journal=Annals of Medicine |volume=53 |issue=1 |pages=972–998 |doi=10.1080/07853890.2021.1925955 |issn=0785-3890 |pmc=8211141 |pmid=34132152}}</ref>
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It is worth noting that it is possible that these are post hoc attributions—the appearance and treatment linked after the medicinal property was discovered.<ref name=":03" /> Depending on the article, remedies connected to the doctrine vary in number and consistency.