Sentence:  In a well-known chapter on phyllotaxis, Coxeter (1969) calls the appearance of the <WSD>Fibonacci sequence</WSD> in botany a "fascinatingly prevalent tendency," called by Cook (1914) the "Law of Wiesner." The prevalence of the <WSD>Fibonacci sequence</WSD> in phyllotactic patterns is often referred to as “the mystery of phyllotaxis,” and “the bugbear of botanists.” 
Meaning of the word marked with <WSD> tags:  The sequence of integers, each of which is the sum of the preceding two, the first and second numbers both being 1.