In 1937 he received his Ph.D. From 1941 to 1959 he was the curator of the Botanical Museum of the University of Helsinki.
[2] In 1963, on the occasion of his seventieth birthday, the 38th volume of the Memoranda Societatis pro Fauna et Flora Fennica was dedicated to him.
[4] Gunnar Marklund specialised in two difficult apomictic groups, the genus Taraxacum (dandelions) and the Ranunculus auricomus group (goldilock buttercups).
[5] He published four monographs, in which he described about two hundred new species,[6] among them for example Ranunculus mendax (Markl.)
& Julin],[13] a goldilock buttercup species known from Sweden and Estonia, and Taraxacum marklundii Palmgr.,[14] a dandelion species described from the Åland Islands,[15] are named in his honour.