Synthesized answer
The provided passages do not contain enough information to fully answer the question about the central thesis of "Genera Plantarum" [1].
The passages only offer the title and author of the work [1]. To determine the central thesis, further content from the book would be required, such as an introduction, preface, or summaries of its core arguments.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: Genera Plantarum, Fifth Edition, 1754 by Carl von Linné