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Darwin 's use of Sprengel 's ideas and reference to this book in the seminal work on the Fertilisation of Orchids established Sprengel 's book as one of the most important works in the field of pollination ecology and its author as a founding father of this field The fact that flowers have a sexual role had been recognised earlier by Linnaeus who did not investigate any functional significance of the visits of insects , but by Sprengel 's time it was known that they were sometimes involved in fertilisation .
 Darwin, Sprengel, Sprengel, Linnaeus, Sprengel
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Darwin, Sprengel, Sprengel, Linnaeus, Sprengel