Hop (Humulus lupulus L.) is a perennial plant cultivated for its use in beer production. The plant is dioecious, and the female plants produce cones containing substances that enhance the taste and durability of beer. Beer was long an essential part of food supply in Northern Europe, and hop has thus been a very important crop during the last 1,000 years. In Sweden, hop cultivation was, by law, mandatory for farmers from 1414 till 1860. Today, Swedish hop cultivation is negligible, but historical remnant hop plants can still be found as feral populations. Using historical maps and documents, we have located ten historical hop yards from the 15 super(th) to 18 super(th) century where hop plants still persist as now feral populations. Some fifteen plants of each population were sampled and genotyped with ten SSR markers and one marker diagnostic for sex type. In addition, 25 genebank preserved clones of older landraces and cultivars from Europe were genotyped. Genotyping results show abundant clonality and low rates of sexual reproduction within the feral populations. Two of the populations had markedly higher genetic diversity and a higher number of haplotypes, and in these populations a mix of female and male plants was also found. The populations were all clearly differentiated, with no haplotypes shared between populations and little evidence of exchange of genetic material. These results indicate that natural spread and genetic recombination is uncommon or slow in Sweden, and that the feral plants could be remnants of the original historical cultivations. In the assembly of European genebank clones, several clones showed identical genotypes and overall limited genetic diversity. The Swedish populations were in most cases genetically clearly different from the genebank clones. This contrasts with historical records of massive introductions of hop clones from continental Europe during the 19 super(th) century and shows that these imports did not replace the original hops being cultivated. A possible better adaption of the Swedish hops and primitive historical breeding are discussed.Original Abstract: Humle (Humulus lupulus L.) aer en flerarig vaext som odlas for anvaendning i olproduktion. Vaexten aer tvabyggare och honplantorna producerar kottar som innehaller aemnen som forbaettrar olets smak och hallbarhet. Oel var laenge en viktig del av livsmedelsforsorjningen i norra Europa, varfor humle varit en mycket betydelsefull groda under de senaste 1000 aren. I Sverige var humleodling enligt lag obligatorisk for jordbrukare fran ar 1414 till 1860. I dag aer den svenska odlingen av humle forsumbar men forvildade humleplantor fran historiska odlingar kan fortfarande hittas. Med hjaelp av historiska kartor och dokument har vi aterfunnit humlebestand fran tio historiska humleodlingar fran 1400- till 1700-talet. Prov togs fran ett femtontal plantor av varje population och genotypades med tio SSR markorer och en markor diagnostisk for kon. Dessutom genotypades 25 kloner av gamla lantsorter och sorter fran Europa bevarade i genbanker. Resultaten visar pa hog grad av klonalitet och lag frekvens av sexuell reproduktion inom populationerna. Tva populationer hade markant hogre genetisk diversitet och ett storre antal haplotyper, i dessa populationer forekom ocksa en blandning av han- och honplantor. Populationerna var alla tydligt differentierade fran varandra och inga haplotyper forkom i mer aen en population, vilket pavisar lagt utbyte av genetiskt material. Dessa resultat tyder pa att naturlig spridning och genetisk rekombination aer ovanligt eller sker langsamt i Sverige. Analysen av de europeiska klonerna fran genbanker visade att flera kloner hade identiska genotyper och totalt sett begraensad genetisk diversitet. De svenska populationerna var i de flesta fall genetiskt klart saerskiljbara fran genbanksklonerna. Detta resultat kontrasterar mot informationen i historiska dokument som beskriver massiv introduktion av humlekloner fran kontinentala Europa under 1800-talet och visar att denna import inte ersatte den humle som tidigare odlats. En mojlig baettre klimatanpassning av de ursprungliga svenska humlesorterna och en eventuell primitiv historisk foraedling diskuteras.