In 1761 Dahl began school in Skara. During school he and his friends were very intrested in natural science. Andreas Dahl, Johan Abraham and Leonard Gyllenhaal, Johan Afzelius, Daniel Naezén and Olof Knös founded on the 13th of December 1769, together with the parish priest and naturalist Clas Bjerkander, "The Swedish Topographic Society in Skara". The members wrote reports about plant- and animallife, geography, topography, historical monuments and economic life mostly from Västergötland. During these years (around 1770) Dahl wrote several essays in different subjects, most of them are unpublished.
On the 3rd of April 1770 Andreas Dahl was enrolled at the University of Uppsala. There he was one of Carl Linnaeus' students. After his father's death in 1771 his family fell into a financial crisis and Andreas had to prematurely end his education. On the 1st of May 1776 he passed a preliminary candidate examination of medicine.
Thanks to recommendations from Linnaeus, Dahl was after his exam employeed as a curator at Claes Alströmer's natural cabinett and botanical garden at Kristinedal in Gamlestaden outside Gothenburg. Andreas Dahl followed Claes Alströmer when he in 1785 moved to his estate Gåsevadsholm outside Kungsbacka, after that he had fallen into a bad economical predicament.
In 1786 Dahl was confered a honorary doctor's degree of medicin in Kiel and in 1787 he became associate professor and botanical demonstrator at the university of Turku (Åbo). To Turku he brought his herbarium which later was destroyed in the big fire in Turku in 1827. Parts of Dahl's collections are preserved and kept in Sahlberg's herbarium in the Botanical Museum at the University of Helsinki and in Giseke's herbarium in the Royal Botanical Garden Edinburgh.
Dahl died in 1789 in Turku in the age of 38.
Andreas was at an early age interested in botany. Anders Tidström, associate professor and disciple of Linnaeus met during his second journey through Västergötland in 1760 the then nine year old Andreas. Tidström tells in his travel diary about Andreas' intrest in botany and his collection of plants recived from his uncle Anders Silvius, chemist in Skara.
After the decease of the son of Carl Linnaeus in 1783 Claes Alströmer recived the so called "herbarium parvum"". This herbarium consisted of duplicates sorted out from Linnaeus herbarium and other plants collected by the younger Linnaeus himself. Alströmer had helped Linnaeus son financially under his journey to England in 1781 and as a thanks Alströmer inherited the herbarium. Dahl has, on every sheet in Alströmer's herbarium written with his legible handwriting whether the sheets came from "a Linné P." or from "a Linné f.", where "P" stands for "Pater" and "f." for "filius". In some cases Dahl himself has recived specimens.
Dahl's friend from school, Adam Afzelius, who in 1785 was employed at the University of Uppsala, was working on a new edition of Linnaeus's Flora Svecica. Andreas Dahl contributed with information about species and plant localities from the Swedish West Coast. He also contributed to the description of several species and to their position in the Flora according to Linnaeus sexual system.
Some of the papers Dahl wrote during his student years in Skara and Uppsala are now kept in the Olof Knös Collection in the county library of Skara. Among those are some inventories over the flora around Skara and Saleby. In the minute-book of "The Swedish Topographic Society in Skara", which is also kept in the Olof Knös Collection, there are also some papers written by Dahl. Inspired by Linnaeus, Dahl wrote a Horologium Florae, a flower-clock over Skara. This paper was posthumous published in "Ny Journal uti Hushållningen", in May-June 1790. The article was probably published by Olof Knös who was the keeper of the minute-book. Also Johan Abraham Gyllenhaal's collections in the university library of Uppsala contain some papers written by Dahl.
On the 3rd of January 1777, an extract from an anonymous letter was published in Inrikes Tidningar. The writer had during his journey from Stockholm to Gothenburg in July 1776 visited "Himmels-Källan" in Varnhem. The quality of the spring was described in the letter and 58 species from the swamp around the spring are noted. Since Andreas Dahl often visited Varnhem and his friend Jonas Odhner it is most likely that the letter came from him.
Andreas Dahl's only publication during his time in Gothenburg was a diary over draggings in the archipelago of Bohuslän published in Trangrum-Acten (Stockholm, 1784). Dahl was one of three members in a commission who wrote a regulation of the waste from the try houses. The wastes from the manufacturing of herring oil was a major problem during the big herring fishing periods and was the cause of sea bed deaths and stinking water. This document was the first Swedish step towards a restriction of industrial waste.
During his few years in Turku Dahl published his most important work: Observationes botanicae circa systema vegetabilium divi a Linne Gottingae 1784 editum, quibus accedit justae in manes Linneanos pietatis specimen. (Kopenhagen, 1787).
In the 1780's, Dahl's friend from Uppsala, Carl Peter Thunberg, named a plant from the plant family Hamamelidaceae after Dahl, Dahlia crinita, but did not publish the name until 1792. The species epithet crinita comes from the Latin word for longhaired which aimed at Dahls big beard. The name Dahlia was though already used in 1791 by the Spaniard Cavanilles for a genus of composite plants introduced to Europe from Mexico in 1784. To the right you can see a specimen of Thunberg's plant, now called Trichocladus crinitus (Thunb.) Pers., from the collections of Swedish Museum of Natural History.
Text: Louise Petrusson
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