Erik Acharius was born in Gävle 1757 and began his studies at Uppsala in 1773. He soon came under the influence of Linneus, and in 1776 he defended the thesis "Planta aphyteja", the last dissertation chaired by Linnaeus. Acharius had financial problems and as he was a skilled artist, in 1778 he took a job as illustrator of natural history objects for the Royal Swedish Academy of Sciences. He continued his studies, however, and prepared for a medical degree which was successfully defended in Lund in 1782. His most important medical appointment was as provincial doctor at Vadstena in 1789, where he remained for the rest of his life. Acharius did much to improve health-care, and he was particularly concerned about the treatment of venereal diseases. A special hospital for this was founded by him at Vadstena in 1795.

Acharius is best known, however, as the "Father of lichenology". How he became interested in lichens is not known with certainty. It could hardly have been Linnaeus who inspired him, for Linnaeus lumped the few lichens known to him into one genus (Lichen). It is probable that he was encouraged to study lichens by his friend Olof Swartz, the botanist with whom Acharius most often discussed his ideas on lichens, which eventually led to his splitting of the collective genus Lichen into some 40 lichen genera. Although he was critized by some contemporary botanists, his work has proved to be of lasting value. Acharius' studies were carefully done, and he had a keen sense for characters distinguishing the species. His four major books are the foundation-stones of lichenology, as is his rich herbarium now in Helsinki (with duplicates at Uppsala University and in the Natural History Museum in London). This well-preserved collection is still actively studied by specialists.

With regard to his private life, Acharius was known to be a gentle and patient person. He was married twice and had ten children. He was made professor in 1803 and, in 1809, he was awarded the Wasa Orden. After 1814 his health began to fail, and in 1819 he died from a stroke, after having spent his last hours studying lichens with his microcope, not noticing the heat of the burning sun.

He was buried with great ceremonial at Vadstena, but his grave there is unmarked today, probably as a result of subsequent reorganisatinn of the churchyard.

In connection with a symposium held by the International Association for Lichenology at Båstad in 1993 a memorial of Acharius was installed on the house where he lived in Vadstena by Prof. Bengt Jonsell of the Swedish Linnaeus Society.

Erik Acharius föddes i Gävle 1757 och började sina studier vid Uppsala universitet redan som 17-åring (1773). Han kom tidigt i kontakt med Linné och 1776 försvarade han avhandlingen "Planta aphyteja", den sista som Linné presiderade för. Acharius var en framstående tecknare och för att tjäna sitt uppehälle vid sidan om fortsatta studier tog han anställning som illustratör (naturalhistoria) vid Kungliga Vetenskapsakademien 1778. Medicine doktorsgrad försvarades framgångsrikt i Lund 1782 och från och med 1789 hade Acharius anställning som provinsialläkare i Vadstena. Främst kom Acharius att ägna sig åt att förbättra hälsovården och 1795 grundade han ett specialsjukhus för att bekämpa veneriska sjukdomar.

Erik Acharius är dock mest känd som grundare av lavforskningen (lichenologien). Hur hans intresse kom att fokuseras mot lavarna vet vi inte med säkerhet men det kan knappast vara Linné som inspirerade eftersom de "lägre växterna" inte lockat Linné i någon högre grad. Troligen uppmuntrades han av sin vän Olof Swartz, som Acharius ofta diskuterade sina nya teorier med och som så småningom ledde till uppdelningen av det kollektiva släktet Lichen i omkring 40 väl avgränsade släkten. Acharius publicerade åtskilliga arbeten men fyra grundläggande verk kom att bilda basen för den moderna lavforskningen, vilket renderat honom epitetet "lichenologiens fader". Hans huvudsamlingar finns i Helsingfors men material finns även vid Uppsala universitet och i London.

I det privata ansågs Acharius vara en vänlig och tålmodig person. Han var gift två gånger och hade tio barn. Han utnämndes till professor 1803 och tilldelades Vasaordern 1809. Efter 1814 började hälsan att svika och han avled 1819 efter att ha suttit i sin trädgård och studerat lavar utan att märka den kraftiga solvärmen.

Erik Acharius fick en ståtlig begravning i Vadstena men hans grav kan idag inte lokaliseras på Vadstena kyrkogård.

Ett minnesmärke över Acharius avtäcktes 1993 i Vadstena på det sk. Acharius-Bergenstrålska huset av Svenska Linnésällskapets ordförande, prof. Bengt Jonsell, i samband med ett internationellt lavsymposium i Båstad (se Svenska Linnésällskapets årsskrift 1992-1993). R.M.