Edvard August Vainio (born Edvard Lang; 5 August 1853 – 14 May 1929) was a Finnish lichenologist. His early works on the lichens of Lapland, his three-volume monograph on the lichen genus Cladonia, and, in particular, his study of the classification and form and structure of lichens in Brazil, made Vainio renowned internationally in the field of lichenology.

Young Vainio's friendship with university student Johan Petter Norrlin, who was nearly eleven years older, helped him develop an impressive knowledge of the local cryptogams (ferns, mosses, algae, and fungi, including lichens) and afforded him ample opportunity to hone his collection and identification techniques at an early age. It was through this association that Vainio met Norrlin's teacher, the prominent lichenologist William Nylander, who supported his early botanical efforts. Vainio's earliest works dealt with phytogeography—elucidating and enumerating the local flora—and are considered the earliest publications on phytogeography in the Finnish language. In these early publications he demonstrated an attention to detail and thoroughness that would become characteristic of his later work.

After graduating from the University of Helsinki in 1880, Vainio became a docent, meaning he was qualified to teach academically, but without a regular salary. Despite his scientific successes and the international recognition he gained through his research, he never obtained a permanent position in this university. This was a result, he said, of his intense Finnish nationalism and desire to promote the use of the Finnish language in academia during a time of language strife, when Latin dominated the scientific literature, and Swedish was the predominant language of administration and education. Disillusioned with his prospects for permanent academic employment, and faced with the reality of having to provide for his family, he was obliged to accept a position with the Russian censorship authority, which led to his ostracism by the Finnish scientific community.

Vainio described about 1900 new species, and published more than 100 scientific works. He made significant scientific collections of lichens, and, as a result of his many years of work as herbarium curator at both the University of Helsinki, and later the University of Turku, he catalogued and processed other collections from all over the world, including the Arctic and Antarctica. Because of the significance of his works on lichens in the tropics and other locales, he has been called the Father of Brazilian lichenology and the Grand Old Man of lichenology.

Edvard Lang was born on 5 August 1853 in Pieksämäki in the eastern Grand Duchy of Finland, part of the Russian Empire. Brought up in a poor home, he was one of several children of bailiff Carl Johan Lang and his wife Adolfina Polén. Edvard's early interest in natural history was manifested in his interest in flowers and his mineral collection; his favourite flower was the marsh willowherb (Epilobium palustre). His eldest brother, Joel Napoleon Lang [fi], was also an avid naturalist, and would later become a well-known legal scholar. In the early 1860s, the family relocated to the municipality of Hollola near Lake Vesijärvi in southern Finland due to his father's work, settling in a farm near the neighbouring municipality of Asikkala. Here Edvard met Johan Petter Norrlin, the son of a neighbour. At the time, Norrlin, who was 11 years his senior, was a university student studying phytogeography, or the geographical distribution of plant species. Norrlin would marry Lang's sister in 1873.

Norrlin had become interested in cryptogams after hearing university lectures given by the well-known lichenologist William Nylander at the Imperial Alexander University (today known as the University of Helsinki), and he became Nylander's student. Norrlin developed an expertise in the local cryptogam flora, particularly the lichens, which are quite diverse in Finland. Lang accompanied and assisted him during field trips in the summers of 1868 and 1869 in the vicinity of Lake Vesijärvi, eagerly absorbing and accumulating knowledge. When Norrlin published Beiträge zur Flora des südöstlichen Tavastlands ("Writings on the flora of south-eastern Tavastia Province") in 1870, he credited Lang—at the time still a schoolboy—for numerous and valuable contributions to his work.

Lang graduated from the Jyväskylä Secondary School [fi] in Jyväskylä in 1870. He began his studies at the Imperial Alexander University the same year, and under the guidance of Norrlin studied botany, phytogeography, and lichenology. As a young student, in 1871, Lang was granted membership in the Societas pro Fauna et Flora Fennica (Finnish Association for Science and Flora), which is the oldest scientific society in Finland. Lang was particularly skilled at identifying and collecting specimens in the field. During the summers of 1873 and 1874 he collected 472 different lichen species from the parishes of Luhanka and Korpilahti in Central Finland, and in spring of the following year, he recorded 324 species in the vicinity of Vyborg. In one of Nylander's publications, eleven new species were described based on the collections of "E. Lang". A grateful Nylander ordered and sent Lang a microscope in the summer of 1874 to help him with his botanical studies. In letters between Norrlin and Nylander, the latter praised Lang's collecting ability, writing "He is a sharp and fit collector of lichens. With a little work and the help of a decent microscope, he will probably soon surpass everyone else in the North, where no one is better than he in this respect." Lang received his Candidate of Philosophy in 1874 and began work on his licentiate degree.

During his time as a graduate student, Vainio, who had by now given up his original surname, published two works on the cryptogams of Finland: Lichenes in viciniis Viburgi observati ("Lichens observed in the vicinity of Viburg") (1878) and Florula Tavastiae orientalis ("Flora of east Tavastia") (1878), which dealt with the results of his collecting excursions. In these publications, Vainio analysed and identified the lichen material he collected from the Vyborg region, including new species observations, without assistance from Norrlin or Nylander. Another early publication, Adjumenta ad Lichenographiam Lapponiae fennicae atque Fenniae borealis ("Adjustments to the lichens of Finnish Lapland and northern Finland"; published in two parts in 1881 and 1883) was based on material he had collected in 1875 and 1877 in desolate locations near the border of the Grand Duchy of Finland and Russia, including North Karelia, Kainuu, Koillismaa, eastern Lapland, and Russian Karelia. Vainio included 626 species in this publication, of which 70 were new to science. He had botanical explorations in Kuusamo and along the Paatsjoki River, but his time on the Russian side of the border was cut short because of lack of funding.