Keller was born in
Saint Petersburg in the
Russian Empire, but grew up in
Volsk and
Saratov where his father was a physician. He graduated from the Saratov Gymnasium in 1892 with a gold medal and joined
Moscow University to study medicine. He however failed in 1892–1993 and moved to the natural sciences under Professor
Ivan Nikolaevich Gorozhankin. For his role in student politics, he was expelled in December 1894 and was arrested in 1896 but released for want of evidence. He moved to the Petrovsky district and worked as a private tutor, and later as a clerk in a book store. In 1898, he received permission to enter university again and joined
Kazan University studying botany under . He graduated in 1902 and taught at Kazan until 1913. In 1907 he worked in collaboration with
Nikolai Dimo on the semi-desert regions. He examined the phytogeography of the steppe and examined classification of the vegetation. He introduced the concept of vegetation complexes that form a distinct layer with species sharing a similar life form, which were later termed as "
synusia". He took a special interest in grasses and plants that are drought and salt tolerant. He then joined the and served at the
University of Voronezh from 1919. In 1931 he was posted as director of a new institute under the
Academy of Sciences of the Soviet Union which was later called the
Komarov Institute. He helped found efforts to produce a Flora of the Soviet Union. He headed the from 1935 and worked at the
Moscow botanical gardens from 1937 until his death. In 1945 he received the
Order of the Red Banner of Labour. == References ==