Could a 400-year-old obscure botany book contain the only surviving portrait of William Shakespeare, one of the world's most prominent literary figure? Writer Mark Griffiths certainly thinks so, according to The Guardian.

The book, titled "Generall Historie of Plantes," or also known simply as "The Herball," was written by horticulturist John Gerard in 1598. It features four men holding various plants and flowers engraved in its cover.

Griffiths, whose claim first appeared in Country Life magazine in which he is a regular contributor, decided to write a book about Gerard, a pioneer in the field of botany and horticulture. In his research, he came across Gerard's book and was intrigued by the figures shown on the cover.

"I began to look at the title page engravings and realized it was full of allusions to people who had been involved in the creation of the book," Griffiths said. "And four of the figures on the title page were, in fact, real persons."

One of the men featured in the cover is Gerard himself. Another figure is Rembert Dodoens, a Flemish botanist. The third man is identified as Lord Burghley, a patron of Gerard who is also Queen Elizabeth's chief minister. When it came to the fourth male, however, Griffith was stuck.

"He's dressed as a Roman, wearing laurels and meant to make us think of Apollo and poetry. I couldn't think of anybody really who was a direct intimate of Gerard's and was involved in writing his book," he said.

However, Griffiths began to look at clues from the Elizabethan society and found out that the people who lived in that era were fond of encoding hidden meanings through symbols. He then turned his attention to the details that surrounded the fourth male to conclude that the person is indeed William Shakespeare.

"For me, it is not about doubt or supposition," Griffiths said. "I'm faced with a series of facts that I can't gainsay, as much as I try. This is what these facts are, these are what the plants are, this is what they signify, this is what the symbol decodes as. All of that adds up to Shakespeare. I can't make that - and believe me I've tried - add up to anybody else but Shakespeare," he explained.

Griffiths believe that Shakespeare posed for the cover of the book at the height of his career which was when he had just finished writing "A Midsummer's Night Dream" and before "Hamlet." He added that the poet was 33 years old at the time of the portrait.

The writer further said that a probable reason as to why Shakespeare was involved in a botany book is that the poet and the horticulturist may had been in similar social circles - thanks to Burghley. Shakespeare, whose literary career may had been helped by the powerful Lord Burghley, could had introduced the former to Gerard who was also an acquaintance.

Before Griffith's sensational claim, the portraits of Shakespeare that the public have seen are all rendered by artists after the poet's death.