View source for Humulus lupulus

{{Short description|Species of flowering plant}}
{{Italic title}}
{{speciesbox
|name = Common hop
|image = Hopfen1.jpg
|genus = Humulus
|species = lupulus
|authority = [[Carl Linnaeus|L.]]
|synonyms =
  {{Plainlist | style = margin-left: 1em; text-indent: -1em; |
* ''Humulus cordifolius'' <small>Miq.</small>
* ''Humulus volubilis'' <small>Salisb.</small> nom. illeg.
* ''Humulus vulgaris'' <small>Gilib.</small>
* ''Lupulus amarus'' <small>Gilib.</small>
* ''Lupulus communis'' <small>Gaertn.</small>
* ''Lupulus humulus'' <small>Mill.</small>
* ''Lupulus scandens'' <small>Lam.</small> nom. illeg.
  }}
|synonyms_ref = <ref>{{ThePlantList |id=kew-2855039 |taxon=Humulus lupulus |authority=L. |access-date=2 February 2016}}</ref>
}}
[[File:Humulus lupulus male flowers RF.jpg|thumb|male inflorescences]]
'''''Humulus lupulus''''', the '''common hop''' or '''hops''', is a [[species]] of [[flowering plant]] in the hemp family, [[Cannabaceae]]. It is a [[perennial]], herbaceous [[climbing plant]] which sends up new shoots in early spring and dies back to a cold-hardy [[rhizome]] in autumn.<ref name=":2">{{Cite web |first=Andrew |last=Sewalish |url=http://bioweb.uwlax.edu/bio203/s2009/sewalish_andr/humulus%20lupulus%20-%20common%20hops/Habitat%20&%20Adaptation.html |title=Habitat & Adaptation |website=Humulus lupulus profile<!-- no title actually given -->|access-date=2017-04-13}}</ref> It is [[dioecious]] (having separate male and female plants) and native to [[West Asia]], [[Europe]] and [[North America]].

As the female cone-shaped flowers ([[hops]]) are used to preserve and flavor [[beer]], the species is widely cultivated for the [[brewing industry]].<ref name=":2" />

== Description ==
''Humulus lupulus'' is a perennial [[herbaceous plant]] up to {{Convert|10|m|abbr=off}} tall, living up to 20 years.<ref name="Food for Thought">{{Cite web |last1=Conway |first1=Sean |last2=Snyder |first2=Reid |date=2008 |title=Humulus lupulus - Hops |url=http://academics.hamilton.edu/foodforthought/Our_Research_files/hops.pdf |access-date=July 31, 2008 |website=College Seminar 235 Food for Thought: The Science, Culture, & Politics of Food |publisher=Hamilton College}}</ref> It has simple [[leaves]] with 3–5 deep lobes that can be opposite or alternate.<ref name="gobotany">{{Go Botany |genus=Humulus |species=lupulus |common=common hop, hops |access-date=2017-04-13}}</ref> The species is triggered by the longer summer days to flower,<ref>{{Cite web |title=HerbalGram: Hops (Humulus lupulus): A Review of its Historic and Medicinal Uses |url=http://cms.herbalgram.org/herbalgram/issue87/article3559.html?ts=1491676763&signature=2e9ee1bc86397f678c6439775de66cdd |access-date=2017-04-08 |website=cms.herbalgram.org }}{{Dead link|date=December 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> usually around July or August in the Northern Hemisphere.<ref>{{Cite web |title=Hop, Humulus lupulus - Flowers |url=http://www.luontoportti.com/suomi/en/kukkakasvit/hop |access-date=2017-04-13 |website=NatureGate}}</ref> The plant is [[dioecious]], with male and female flowers on separate plants. The fragrant flowers are [[wind-pollinated]].<ref>{{Cite web |title=Hops, Humulus lupulus, plant facts |url=https://www.edenproject.com/learn/for-everyone/plant-profiles/hops |access-date=2017-04-12 |website=Eden Project}}</ref> The staminate (male) flowers do not have petals, while the pistillate (female) flowers have petals enveloping the fruit. The female flower cones (or [[strobili]]) are known as [[hops]].<ref name="Food for Thought" /> The fruit is an [[achene]], meaning that it is dry and does not split open at maturity.<ref name="gobotany"/> The achene is surrounded by tepals and lupulin-secreting glands are concentrated on the fruit.<ref>{{cite web |title=''Vitis riparia'' |url=http://climbers.lsa.umich.edu/?p=465 |website=CLIMBERS: Censusing Lianas in Mesic Biomes of Eastern Regions |first=Robyn J. |last=Burnham |date=2014 |publisher=University of Michigan College of Literature, Sciences and the Arts  |access-date=2017-04-02}}</ref><ref name=":0">{{Cite web|url=https://hort.purdue.edu/newcrop/duke_energy/Humulus_lupulus.html |title=''Humulus lupulus'' |website=NewCROP, the New Crop Resource Online Program |access-date=2017-04-02}}</ref>

The species is sometimes described as a [[bine (botany)|bine]] rather than a vine because it has stiff downward facing hairs that provide stability and allow it to climb.<ref name="Food for Thought" />

=== Chemistry ===
''H.&nbsp;lupulus'' contains [[myrcene]], [[humulene]], [[xanthohumol]], [[myrcenol]] and [[linalool]],<ref>{{cite journal |doi=10.1016/j.jep.2008.01.011 |title=Pharmacognostic and pharmacological profile of Humulus lupulus L |date=2008 |last1=Zanoli |first1=Paola |last2=Zavatti |first2=Manuela |journal=Journal of Ethnopharmacology |volume=116 |issue=3 |pages=383–396 |pmid=18308492 }}</ref> as well as less defined [[tannin]]s and [[resin]].

[[Hops]] are unique for containing [[Secondary metabolite|secondary metabolites]], [[flavonoid]]s, [[oil]]s, and [[polyphenol]]s that impact the flavor of the products they are common in, such as [[beer]].<ref name=":3">{{Cite journal |last1=Eriksen |first1=Renée L. |last2=Padgitt-Cobb |first2=Lillian K. |last3=Townsend |first3=M. Shaun |last4=Henning |first4=John A.  |last12=Hendrix |first12=David A. |date=December 2021 |title=Gene expression for secondary metabolite biosynthesis in hop (Humulus lupulus L.) leaf lupulin glands exposed to heat and low-water stress |url= |journal=Scientific Reports |language=en |volume=11 |issue=1 |pages=5138 |bibcode=2021NatSR..11.5138E |doi=10.1038/s41598-021-84691-y |issn=2045-2322 |pmc=7970847 |pmid=33664420}}</ref> The bitter flavors in hops can be accounted for by acids composed of [[Prenylation|prenylated]] [[polyketide]]s (a group of secondary metabolites), which highly impact the taste of hop-based products.<ref>{{Cite journal |last1=Goese |first1=Markus |last2=Kammhuber |first2=Klaus |last3=Bacher |first3=Adelbert |last4=Zenk |first4=Meinhart H. |last5=Eisenreich |first5=Wolfgang |date=1999-07-15 |title=Biosynthesis of bitter acids in hops. A 13C-NMR and 2H-NMR study on the building blocks of humulone |journal=European Journal of Biochemistry |volume=263 |issue=2 |pages=447–454 |doi=10.1046/j.1432-1327.1999.00518.x |issn=0014-2956 |pmid=10406953|doi-access=free }}</ref> Multiple genes have been identified as factors in the expression of taste including {{Nowrap|[[Catechol-O-methyltransferase|O-methyltransferase 1]]}}, geranyl diphosphate [[synthase]], and [[chalcone]] synthase. [[Genomic]] analyses have shown evidence that the intervention of humans in the selection process of the hop over the thousands of years it has been cultivated have provided noticeable enhancements in aroma and bitterness as well as selection of varieties with high yield rates.<ref name=":5">{{Cite journal |last1=Natsume |first1=S. |last2=Takagi |first2=H. |last3=Shiraishi |first3=A. |last4=Murata |first4=J. |last5=Toyonaga |first5=H. |last6=Patzak |first6=J. |last7=Takagi |first7=M. |last8=Yaegashi |first8=H. |last9=Uemura |first9=A. |last10=Mitsuoka |first10=C. |last11=Yoshida |first11=K. |date=2014-11-20 |title=The Draft Genome of Hop (Humulus lupulus), an Essence for Brewing |journal=Plant and Cell Physiology |volume=56 |issue=3 |pages=428–441 |doi=10.1093/pcp/pcu169 |issn=0032-0781 |pmid=25416290 |doi-access=}}</ref>

==== Flowering, growth, and stress response ====
[[File:Hop plant by Kent Ditch - geograph.org.uk - 5892896.jpg|thumb|''Humulus lupulus'', in Kent, England. Taken in late August, showing light-green cones.]]
Predicted genes in [[Homologous chromosome|homologous]] primary contigs have been identified as accounting for various traits [[Gene expression|expressed]] via variation in the growth, flowering, and stress responses in the plant. These homologous primary contigs correspond to regions with large amounts of [[Sequence homology|sequence variation]]. [[Gene|Genes]] in the hop that contain higher rates of [[Sequence homology|sequence divergence]] in homologous primary contigs (overlapping [[DNA sequences]] inherited by a common ancestor) have been attributed to the expression of flowering, growth and responses to (both [[Abiotic stress|abiotic]] and [[Biotic stress|biotic]]) stress in the plant. The responses to stress are thought to manifest in the distinct differences and difficulties in the cultivation processes between geographically popular varieties of the hop plant.<ref name=":6">{{Cite journal |last1=Padgitt-Cobb |first1=Lillian K. |last2=Kingan |first2=Sarah B. |last3=Wells |first3=Jackson |last4=Elser |first4=Justin |last5=Kronmiller |first5=Brent |last6=Moore |first6=Daniel |last7=Concepcion |first7=Gregory |last8=Peluso |first8=Paul |last9=Rank |first9=David |last10=Jaiswal |first10=Pankaj |last11=Henning |first11=John |last12=Hendrix |first12=David A. |date=2021-02-18 |title=A draft phased assembly of the diploid Cascade hop ( Humulus lupulus ) genome |journal=The Plant Genome |volume=14 |issue=1 |pages=e20072 |doi=10.1002/tpg2.20072 |issn=1940-3372 |pmid=33605092 |doi-access=free |s2cid=231962731}}</ref> Outside environmental stress, such as changes in temperature and water availability has also been shown to significantly alter the [[transcriptome]] and incite reductions in genes known to be involved in the synthesis of [[Secondary metabolite|secondary metabolites]] (including bitter acids), which are [[Organic compound|organic compounds]] produced that do not impact development or reproduction of hops. Environmental stress has also been shown to reduce [[Gene expression|expression]] of the [[valerophenone]] [[synthase]] [[gene]], which is known to be an essential genetic component in the regulation of bitter acid production. This shows that impacts of outside stress on ''H.&nbsp;lupulus'' likely has a direct implication of the expression of the bitter flavor that remains an essential component of the popularity of the plant.<ref name=":3" />

==== Research ====
* ''Humulus lupulus'' contains xanthohumol, which is converted by large intestine bacteria into the [[phytoestrogen]] [[8-prenylnaringenin]], which may have a relative binding affinity to [[estrogen]] receptors<ref>{{cite journal |vauthors=Milligan SR, Kalita JC, Heyerick A, Rong H, De Cooman L, De Keukeleire D |date=June 1999 |title=Identification of a potent phytoestrogen in hops (Humulus lupulus L.) and beer |journal=J Clin Endocrinol Metab |volume=84 |issue=6 |pages=2249–52 |doi=10.1210/jcem.84.6.5887 |pmid=10372741 |doi-access=free}}</ref> as well as potentiating effects on [[GABAA receptor|GABA<sub>A</sub> receptor activity]]<ref>{{Cite journal |last1=Benkherouf |first1=Ali Y. |last2=Soini |first2=Sanna L. |last3=Stompor |first3=Monika |last4=Uusi-Oukari |first4=Mikko |date=February 2019 |title=Positive allosteric modulation of native and recombinant GABAA receptors by hops prenylflavonoids |journal=European Journal of Pharmacology |volume=852 |pages=34–41 |doi=10.1016/j.ejphar.2019.02.034 |issn=0014-2999 |pmid=30797788 |s2cid=73456325}}</ref>
* ''Humulus lupulus'' extract is antimicrobial, an activity which has been exploited in the manufacture of natural deodorant.<ref>{{cite web |title=Hops &#91;CO2&#93; Extract |url=http://www.tomsofmaine.com/products/ingredient-detail.aspx?id=110&amp;name=Hops%20%5BCO2%5D%20extract |url-status=dead |archive-url=https://web.archive.org/web/20131224112745/http://www.tomsofmaine.com/products/ingredient-detail.aspx?id=110&amp%3Bname=Hops%20%5BCO2%5D%20extract |archive-date=December 24, 2013 |access-date=2009-06-06 |publisher=Toms of Maine}}</ref>
* Spent ''H. lupulus'' extract has also been shown to have [[antimicrobial]] and anti-[[biofilm]] activities, raising the possibility this waste product of the brewing industry could be developed for medical applications.<ref name="pmid24175280">{{cite journal |vauthors=Rozalski M, Micota B, Sadowska B, Stochmal A, Jedrejek D, Wieckowska-Szakiel M, Rozalska B |year=2013 |title=Antiadherent and Antibiofilm Activity of Humulus lupulus L. Derived Products: New Pharmacological Properties |journal=BioMed Research International |volume=2013 |pages=1–7 |doi=10.1155/2013/101089 |pmc=3794639 |pmid=24175280 |doi-access=free}}</ref>
* Extracts of  the bitter alpha-acids present in ''H. lupulus'' have been shown to decrease nocturnal activity, acting as a sleep aide, in certain concentrations.<ref>{{Cite journal |last1=Franco |first1=L. |last2=Sánchez |first2=C. |last3=Bravo |first3=R. |last4=Rodriguez |first4=A. |last5=Barriga |first5=C. |last6=Juánez |first6=Javier Cubero |date=2012-06-01 |title=The sedative effects of hops (Humulus lupulus), a component of beer, on the activity/rest rhythm |journal=Acta Physiologica Hungarica |volume=99 |issue=2 |pages=133–139 |doi=10.1556/APhysiol.99.2012.2.6 |issn=0231-424X |pmid=22849837}}</ref>
Because of the growing understanding regarding the hop's overlap in gene structures with [[cannabidiolic acid synthase]], the precursor structure to [[cannabidiol]], there is a gap in general understanding about potential unknown compounds and benefits in hops. As the understanding of the health benefits available in cannabidiol increases, there is a growing demand to further investigate the overlap between cannabidiolic acid synthase and ''H.&nbsp;lupulus''.<ref name=":7">{{Cite web |title=Advancing understanding of hop genome to aid brewers, medical researchers |url=https://www.sciencedaily.com/releases/2021/02/210222092258.htm |access-date=2021-04-09 |website=ScienceDaily |language=en}}</ref>

===== Limitations =====
The [[genome]] of ''H. lupulus'' is relatively large and has been shown to be a similar size to the [[human genome]]. The complexity of the hop genome has made it difficult to understand and identify unknown genetic properties, however with the growing availability of accessible [[DNA sequencing|sequencing]], there is room for more advanced understanding of the plant.<ref name=":7" /> Because of the growing concern of [[climate change]], and the assumption that there will be an increase of [[Heat wave|heat waves]], it is likely that growing large yields of hops could become more difficult. This could result in changes to the [[transcriptome]] of the hop, or result in a decrease of certain varieties, leaving less room for further research.<ref name=":3" />

== Taxonomy ==

=== Relation to ''Cannabis sativa'' ===
The hop is within the same family of plants such as [[hemp]] and [[Cannabis (drug)|marijuana]], called [[Cannabaceae]].<ref name=":6" /> The hop plant diverged from ''[[Cannabis sativa]]'' over 20 million years ago and has evolved to be three times the physical size.<ref>{{Cite journal |last1=Divashuk |first1=Mikhail G. |last2=Alexandrov |first2=Oleg S. |last3=Razumova |first3=Olga V. |last4=Kirov |first4=Ilya V. |last5=Karlov |first5=Gennady I. |date=2014-01-21 |title=Molecular Cytogenetic Characterization of the Dioecious Cannabis sativa with an XY Chromosome Sex Determination System |url= |journal=PLOS ONE |volume=9 |issue=1 |pages=e85118 |bibcode=2014PLoSO...985118D |doi=10.1371/journal.pone.0085118 |issn=1932-6203 |pmc=3897423 |pmid=24465491 |doi-access=free}}</ref><ref>{{Cite journal |last1=Murakami |first1=A |last2=Darby |first2=P |last3=Javornik |first3=B |last4=Pais |first4=M S S |last5=Seigner |first5=E |last6=Lutz |first6=A |last7=Svoboda |first7=P |date=2006-05-10 |title=Molecular phylogeny of wild Hops, Humulus lupulus L. |journal=Heredity |volume=97 |issue=1 |pages=66–74 |doi=10.1038/sj.hdy.6800839 |issn=0018-067X |pmid=16685279 |doi-access=free |s2cid=11920277}}</ref><ref name=":5" /><ref>{{Cite journal |last1=Pisupati |first1=Rahul |last2=Vergara |first2=Daniela |last3=Kane |first3=Nolan C. |date=2018-02-21 |title=Diversity and evolution of the repetitive genomic content in Cannabis sativa |url= |journal=BMC Genomics |volume=19 |issue=1 |page=156 |doi=10.1186/s12864-018-4494-3 |issn=1471-2164 |pmc=5822635 |pmid=29466945 |doi-access=free }}</ref> The hop and ''C.&nbsp;sativa'' are estimated to have approximately a 73% overlap in genomic content.<ref>{{Cite journal |last1=Laverty |first1=Kaitlin U. |last2=Stout |first2=Jake M. |last3=Sullivan |first3=Mitchell J. |last4=Shah |first4=Hardik |last5=Gill |first5=Navdeep |last6=Holbrook |first6=Larry |last7=Deikus |first7=Gintaras |last8=Sebra |first8=Robert |last9=Hughes |first9=Timothy R. |last10=Page |first10=Jonathan E. |last11=van Bakel |first11=Harm |date=2018-11-08 |title=A physical and genetic map of Cannabis sativa identifies extensive rearrangements at the THC/CBD acid synthase loci |url= |journal=Genome Research |volume=29 |issue=1 |pages=146–156 |doi=10.1101/gr.242594.118 |issn=1088-9051 |pmc=6314170 |pmid=30409771}}</ref> The overlap between [[Enzyme|enzymes]] includes [[Polyketide|polyketide synthases]] and [[Prenyltransferase|prenyltransferases]].<ref>{{Cite journal |last1=Marks |first1=M. David |last2=Tian |first2=Li |last3=Wenger |first3=Jonathan P. |last4=Omburo |first4=Stephanie N. |last5=Soto-Fuentes |first5=Wilfredo |last6=He |first6=Ji |last7=Gang |first7=David R. |last8=Weiblen |first8=George D. |last9=Dixon |first9=Richard A. |date=2009-07-06 |title=Identification of candidate genes affecting Δ9-tetrahydrocannabinol biosynthesis in Cannabis sativa |url= |journal=Journal of Experimental Botany |volume=60 |issue=13 |pages=3715–3726 |doi=10.1093/jxb/erp210 |issn=1460-2431 |pmc=2736886 |pmid=19581347}}</ref> The hop and ''C.&nbsp;sativa'' also have significant overlap in the [[cannabidiolic acid]] synthase gene, which is expressed in the tissues of the leaves in both plants.<ref name=":6" />

=== Varieties ===
[[File:Humle (Humulus lupulus)-2017-Ystad.jpg|thumb|Cultivation of hops in [[Ystad|Ystad, Sweden]] 2017]]
[[File:Humulus lupulus 'Aurea' - Golden Hop.jpg|thumb|'Golden' hop]]
The five varieties of this species (''Humulus lupulus'') are:
* ''H. l.'' var. ''lupulus'' – Europe, western Asia
* ''H. l.'' var. ''cordifolius'' – eastern Asia
* ''H. l.'' var. ''lupuloides'' (syn. ''H. americanus'') – eastern North America
* ''H. l.'' var. ''neomexicanus'' – western North American.<ref>{{PLANTS |symbol=HULUN |taxon=Humulus lupulus'' var. ''neomexicanus |access-date=May 5, 2016}}</ref>
* ''H. l.'' var. ''pubescens'' – midwestern and eastern North America<ref>{{GRIN |access-date=2018-07-31}}</ref><ref>{{PLANTS |symbol=HULUP |taxon=Humulus lupulus'' var. ''pubescens}}</ref>

Many [[cultivar|cultivars]] are found in the [[list of hop varieties]]. A yellow-leafed ornamental cultivar, ''Humulus lupulus'' 'Aureus', is cultivated for garden use. It is also known as golden hop, and holds the [[Royal Horticultural Society]]'s [[Award of Garden Merit]] (AGM).<ref name="RHS">{{cite web|url= https://www.rhs.org.uk/Plants/91715/Humulus-lupulus-Aureus/Details |title=Humulus lupulus 'Aureus' AGM|work=RHS Plant Selector|publisher=[[Royal Horticultural Society]]|access-date=25 August 2020}}</ref><ref>{{cite web  | url= https://www.rhs.org.uk/plants/pdfs/agm-lists/agm-ornamentals.pdf | title = AGM Plants - Ornamental | date = July 2017 | page = 43 | publisher = Royal Horticultural Society | access-date = 3 March 2018}}</ref>

=== Etymology ===
The genus name ''Humulus'' is a medieval name that was at some point Latinized after being borrowed from a Germanic source exhibiting the '''h•m•l''' consonant cluster, as in Middle Low German ''homele''. 

According to Soviet Iranist [[Vasily Abaev]] this could be a word of [[Sarmatian]] origin which is present in the modern Ossetian language ({{langx|os|Хуымæллæг}}) and derives from proto-Iranian ''hauma-arayka'', an ''[[Aryans|Aryan]] [[haoma]]''.<ref>Абаев В. И. Историко-этимологический словарь осетинского языка. Т. 4. М.—Л., 1989. С. 261-262.</ref> 

From Sarmatian dialects this word spread across Eurasia, thus creating a group of related words in Turkic, Finno-Ugric, Slavic and Germanic languages (see {{langx|ru|хмель}}, [[Chuvash language|Chuvash]] ''хăмла'', [[Finnish language|Finnish]] ''humala'', [[Hungarian language|Hungarian]] ''komló'', [[Mordovian]] ''комла'', [[Avar language|Avar]] ''хомеллег'').

The specific epithet ''lupulus'' is Latin for "small wolf".<ref name=":1">{{Cite web |title=Humulus lupulus |url=http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=f191 |access-date=2017-04-12 |website=Plant Finder |publisher=Missouri botanical Garden}}</ref> The name refers to the plant's tendency to strangle other plants, mainly [[common osier|osiers]] or basket willows (''Salix viminalis''), like a wolf does a sheep.<ref name="Food for Thought" /> Hops could be seen growing over these willows so often that it was named the willow-wolf.<ref name=":1" />

The English word ''hop'' is derived from the [[Middle Dutch]] word {{lang|dum|hoppe}}, also meaning ''Humulus lupulus''.<ref>{{OEtymD|hop}}</ref>

== Distribution and habitat ==
The plant is [[Native species|native]] to Europe, western Asia and North America.<ref name=":1" />

It grows best in the latitude range of 38°–51° in full sun with moderate amounts of rainfall.<ref name=":2" />

== Ecology ==
The flowers attract [[butterflies]],<ref name=":1" /> amongst other insects.

=== Animal pests ===
* Damson hop aphid (''[[Phorodon humuli]]'')
* Two spotted spider mite (''[[Tetranychus urticae]]'')
* Japanese beetle (''[[Popillia japonica]]'')
* Comma butterfly (''[[Polygonia c-album]]'')
* Pale tussock moth (''[[Calliteara pudibunda]]'')
* Currant pug moth (''[[Currant pug|Eupithecia assimilata]]'')
* Buttoned snout moth (''[[Hypena rostralis]])''
* Buff ermine moth (''[[Buff ermine|Spilosoma lutea]]'')

=== Diseases ===
{{main|List of hop diseases}}
* [[Downy mildew]] (''[[Pseudoperonospora humuli]]'')
* [[Powdery mildew]] (''[[Podosphaera macularis]]'')

== Toxicity ==
''H. lupulus'' can cause dermatitis to some who handle them. It is estimated that about 1 in 30 people are affected by this.<ref name=":0" />

== Uses ==
=== In alcohol brewing===
{{main|Hops}}

''H. lupulus'' is first mentioned in 768 CE when [[Pepin the Short|King Pepin]] donated hops to a monastery in Paris. Cultivation was first recorded in 859 CE, in documents from a monastery in [[Freising]], Germany.<ref name=":4">{{Cite journal |last=Behre |first=Karl-Ernst |year=1999 |title=The history of beer additives in Europe - a review |url=https://www.researchgate.net/publication/226208521 |journal=Vegetation History and Archaeobotany |volume=8 |issue=1–2 |pages=35–48 |doi=10.1007/BF02042841 |bibcode=1999VegHA...8...35B |s2cid=129429552}}</ref>

The chemical compounds found in ''H. lupulus'' are the main components in flavoring and bittering beer. The fragrant flower cones, known as hops, impart a bitter flavor and also have aromatic and preservative qualities.<ref>{{cite journal |vauthors=Langezaal CR, Chandra A, Scheffer JJ |date=1992 |title=Antimicrobial screening of essential oils and extracts of some Humulus lupulus L. cultivars |journal=Pharm Weekbl Sci |volume=14 |issue=6 |pages=353–356 |doi=10.1007/bf01970171 |pmid=1475174 |s2cid=12561634}}</ref> Some other compounds help with creating foam in beer. Chemicals such as [[linalool]] and [[aldehyde]]s contribute to the flavor of beer. The main components of bitterness in beer are [[Alpha acid|iso-alpha acids]], with many other compounds contributing to beer's overall bitterness.<ref>{{Cite journal|url=http://onlinelibrary.wiley.com/store/10.1002/j.2050-0416.2011.tb00471.x/asset/j.2050-0416.2011.tb00471.x.pdf?v=1&t=j1qr8dsg&s=f82746474fe24332c8d300aa8504f97861f3892b|doi=10.1002/j.2050-0416.2011.tb00471.x|title=125th Anniversary Review: The Role of Hops in Brewing|journal=Journal of the Institute of Brewing|volume=117|issue=3|pages=259–267|year=2011|last1=Schönberger|first1=C.|last2=Kostelecky|first2=T.|doi-access=free}}</ref> Until the Middle Ages, many varieties of plant were used to flavor beer, including most commonly ''[[Myrica gale]]''.<ref name=":4" /> ''H.&nbsp;lupulus'' became favored because it contains preserving agents which prolong the viability of a brew.

===Outside alcohol production===
Buds or hops of ''Humulus lupulus'' are used in Iranian ethnomedicine as a [[sedative]].<ref>{{cite journal |last1=Buso |first1=Piergiacomo |last2=Manfredini |first2=Stefano |last3=Reza Ahmadi-Ashtiani |first3=Hamid |last4=Sciabica |first4=Sabrina |last5=Buzzi |first5=Raissa |last6=Vertuani |first6=Silvia |last7=Baldisserotto |first7=Anna |title=Iranian Medicinal Plants: From Ethnomedicine to Actual Studies |journal=[[Medicina (journal)|Medicina]] |date=26 February 2020 |volume=56 |issue=3 |page=18 |doi=10.3390/medicina56030097|doi-access=free |pmid=32110920 |pmc=7143749 }}</ref>

==In culture==
''H. lupulus'' was voted the [[County flowers of the United Kingdom|county flower]] of [[Kent]] in 2002 following a poll by the wild flora conservation charity [[Plantlife]].<ref>Plantlife website [http://www.plantlife.org.uk/wild_plants/county_flowers/ ''County Flowers page''] {{webarchive|url=https://web.archive.org/web/20150430170312/http://www.plantlife.org.uk/wild_plants/county_flowers/ |date=2015-04-30 }}</ref>

== References ==
{{Reflist}}

=== Bibliography ===
* "Czech hop varieties". Žatec: Chmelařský institut, 2012. [http://www.chizatec.cz/download/page5021.pdf on-line]
* Barchet, Ron. "German hops in craft brewing". Wolnzach: Hopfen-Rundschau, 2014.
* Biendl, Martin. "Hops and health". Wolnzach: German Hop Museum, 2013.
* Hieronymus, Stan. "For the love of hops: The practical guide to aroma, bitterness and the culture of hops". Boulder, CO: Brewers Publications, a division of the Brewers Association, 2012.
* Kopp, Sylvia. "Barley & hops: The craft beer book". Berlin: Gestalten, 2014.
* Melnychuk, M. D.; Boyko, A. L.; Hryhoryuk, I. P.; Likhanov, A. F.; Klyuvadenko, A. A.; Martyn, H. H.; Kukovenko, V. I. "Hop (''Humulus lupulus'' L.): From cell to plant". Kyiv: Printeko, 2013.
* Nesvadba, Vladimír. "Development and tradition of Czech hop varietes". Žatec: Hop Research Institute, 2013.
* Neve, Ray A. "Hops". London: Chapman and Hall, 1991.
* Skomra, Urszula. "Polish hop cultivars". Puławy: Institute of Soil Science and Plant Cultivation, 2010. 

== External links ==
{{Commons}}
* [https://hort.purdue.edu/newcrop/duke_energy/Humulus_lupulus.html Purdue University article]
* [http://www.botanical.com/botanical/mgmh/h/hops--32.html Botanical.com - a wealth of information on the Hop plant and its past and modern uses]
* [http://www.armeniapedia.org/index.php?title=Humulus_lupulus Armeniapedia.org - Medicinal uses of hops in Armenia]
* 2005-10-25 Oregon State University ''[https://web.archive.org/web/20070121185641/http://oregonstate.edu/dept/ncs/newsarch/2005/Oct05/beerandcancer.htm Anti-cancer Compound in Beer Gaining Interest]''

{{Authority control}}
{{Taxonbar|from=Q104212}}

[[Category:Hop varieties|lupulusa]]
[[Category:Plants described in 1753]]
[[Category:Taxa named by Carl Linnaeus]]
[[Category:Humulus|lupulus]]
[[Category:Cannabaceae]]
[[Category:Perennial plants]]