Finnish entomologist and botanist (lichenologist), brother of botanist Fredrik Nylander. William Nylander followed his brother in studying natural history and medicine and was initially interested in entomology. As a student he travelled much of Finland in search of insects and, in 1846, published a long treatise on the ants of northern Europe. At the same time he was active within the Societas pro Fauna et Flora Fennica (the natural history society of Finland) and was an instigator of the society's publication, of which the first volume was half taken up with his own papers on insects.

Soon after receiving his PhD (1847) Nylander's attention turned almost exclusively to the plants of Finland, and he set about publishing the first coherent flora for the country. E. Fries had recently published a Scandinavian flora, which covered some aspects of Finnish vegetation, although there was much to be added and Nylander did so in his Animadversiones circa distributionem plantarum Fennia (1852). Soon afterwards he published a flora of Helsinki and one of Karelia, both of which were seminal in their inclusion of cryptogamic plants. Continuing this theme he started to focus on lichens.

Studying abroad between 1851 and 1859, he visited London, Brussels, Berlin, Uppsala and, significantly, Paris. Here, working in the Jardin des Plantes, he developed quite a name for himself and soon entered into international correspondence on the subject. By 1854 he was able to publish an important work on Lichen classification entitled Essai d'une nouvelle classification des Lichens and set to work on a grand ambition of his, to produce a synopsis of all known lichen species.

From 1857 his money began to run low and, although Nylander desperately wanted to stay in Paris, he decided to apply for the botany and zoology professorship which remained vacant at the Imperial Alexander University in Helsinki. He was appointed that same year but remained in France until 1858, before returning home. Setting to work developing the museum and garden of the university, Nylander worked tirelessly and in 1859 brought out a catalogue of all the specimens held in their herbarium. Made president of the Societas pro Fauna et Flora Fennica, he set about organising field trips around Finland as well as to Russian Lapland and Karelia.

Over the following years he returned to Paris twice in order to work on his lichen monograph and published part one of this Synopsis in 1860. The same year Nylander published Lichenographia scandinavica but in 1862 he abruptly resigned from the university and remained in Paris where he became a world authority on lichens. As his reputation grew during the 1870s, Nylander began receiving specimens from all over the globe. Unfortunately, due to the sheer number received, he was never able to complete his Synopsis: the task was simply too great for one man, however industrious he was.

Nylander was completely obsessive about his work and a solitary man; locking himself away for long periods he was completely unwilling to accept the results of any other scientists. He made a lot of enemies in Paris because of his obstinacy and the ease with which he would take offence. These traits may have contributed to his inability to complete his Synopsis, but his contributions to lichenology were great. Producing some 300 publications he described 3,689 species during his life. After his resignation the university granted Nylander a lifelong pension in return for his herbarium, and the 50,000 or so varieties collected during his lifetime are still held by what is now the University of Helsinki (H).

Sources:
R. Colander, 1965, The History of Botany in Finland.