Gustav Adolf Hugo Dahlstedt was a Swedish botanist who worked at the Bergianska Trädgården and Naturhistoriska Riksmuseet in Stockholm. In 1907 he received his honorary doctorate.
Dahlstedt specialized in research of the plant genera Taraxacum and Hieracium, of which he circumscribed many species. The botanical genus Dahlstedtia from the subfamily Faboideae is named in his honor, as are taxa with the specific taxa of dahlstedtii, an example being Taraxacum dahlstedtii, a plant sometimes referred to as "Dahlstedt's dandelion".