Hoffstad was born in
Stjørdalshalsen,
Nordre Trondhjems Amt, a son of the tradesman Oliver Hoffstad (1830–1878) and his wife Anne Birgitte Øydahl (1843–1932). In 1883, then aged 18, the young Hoffstad
finished secondary education at
Trondhjem Cathedral School, graduating with a
cand.real. degree five years later. He subsequently taught at girls' schools in
Trondhjem,
Egersund,
Haugesund and
Røros for shorter periods before and after 1890. In the latter year he married Valborg Olsen, a photographer's daughter three years his junior. They had a son,
Einar Hoffstad, who became an economist and encyclopedist. On 1 August 1892 he was employed by the
Sandefjord Upper Secondary School (), at which school he would teach for the remainder of his productive life. From the beginning he was hired as secondary teacher , but advanced positions over time, becoming both adjunct teacher and lecturer. In 1924, then aged 59, he was appointed principal of the school—he quit teaching at Sandefjord Technical Evening School () in the same year, where he had lectured concurrently with his teaching at the Upper Secondary School. In 1891, he published
Norsk Flora, a
flora for Norwegian schools which was published in eight further editions before Hoffstad's decease in 1943. He also published another illustrated Flora for Norwegian schools, entitled
Flora for skoler (1899). In the summers of 1896 and 1897, Hoffstad travelled from the estuary of the
Trondheimsfjord to
Leka Municipality, at the border between
Nordland and Nord-Trøndelag counties. He wrote an article for the journal
Nyt Magasin for Naturvidenskaberne in 1899 where he described what he had observed, amongst other things the discovery of
Utricularia ochroleuca in Northern Norway. Hoffstad was also engaged in politics. In 1894, he became leader of a conservative youth league in Sandefjord. He became a member of Sandefjord city council in 1897, and became deputy mayor already in 1898. From 1911 to 1934, he served as mayor for Sandefjord, the longest time any major not born in the city ever had served. Whilst serving as mayor, Hoffstad wrote two treatises on the management of municipal finances in the city:
Kommunale finanser (1926) and
Sandefjords kommunale økonomi i tiåret 1922—1932 (1933). He also represented the
Conservative Party in the
Parliament of Norway as a deputy representative in the 1919–21, 1922–24 and 1931–33 terms. His constituency was
Larvik og Sandefjord, from 1922 changed to the
Market towns of Vestfold county. He chaired the board of the newspaper
Sandefjords Blad, and was a board member of
Vestfold Kraftselskap from 1921 to 1929, Sandefjord Sparebank, the local gas works, electricity plant and cinema as well as the teachers' union
Filologenes og Realistenes Landsforening. He founded a regional branch of the
Union of Norwegian Cities in 1921, and chaired it until 1934. He died of a
heart attack in September 1943. At the deathbed, he proofread the ninth edition of
Norsk Flora, which was published posthumously in 1944. ==References==