In 1729 his botanical knowledge was brought to the attention of Olaf Rudbeck, professor of botany in the University of Upsala, by a short paper on the sexes of plants which Linnaeus had prepared.

Rudbeck was so impressed by some of the ideas expressed in this paper that he appointed the author as his assistant the following year.
This was the beginning of Linnaes's career as a botanist.

The academic gardens were thus thrown open to him, and he found time at his disposal for pursuing his studies between lecture hours and in the evenings.

It was at this time that he began the preparation of his work the Systema naturae, the first of his great works, containing a comprehensive sketch of the whole field of natural history.

When this work was published, the clearness of the views expressed and the systematic arrangement of the various classifications excited great astonishment and admiration, and placed Linaeus at once in the foremost rank of naturalists.