The Different Forms of Flowers on Plants of the Same Species

The Different Forms of Flowers on Plants of the Same Species is a book by Charles Darwin first published in 1877. It is the fifth of his six books devoted solely to the study of plants (excluding The Variation of Animals and Plants under Domestication).

These writings contributed to Darwin's pursuit of evidence that would support his theory of natural selection. There were only two more books to follow: The Power of Movement in Plants (1880) and The Formation of Vegetable Mould through the Action of Worms (1881). He conducted a wide range of experiments and observations and the results of these form the framework of the book. He was assisted in this work by his son, Francis Darwin who also wrote a preface for the second edition which was published two years after his father's death in 1882. The book was dedicated to his longtime friend and colleague, Harvard botany professor Asa Gray "as a small tribute of respect and affection".

Using the four classifications established by Carl Linnaeus (hermaphroditic, monoecious, dioecious, polygamous), Darwin concentrated on two divisions of the hermaphroditic class, namely the cleistogamic and heterostyled.

Darwin’s reflections indicate the economy of nature through a process of gradual modification of plants, their structures being modified and degraded for the purpose of the large scale production of seed which is necessary and advantageous for survival. Darwin states (p. 227): "Cleistogamic flowers ... are admirably fitted to yield a copious supply of seed at a wonderfully small cost to the plant."

Francis Darwin indicated that the work on heterostylism had given his father extreme pleasure, especially as it had been one of the most puzzling bits of work he ever carried out. Darwin thought that hardly anyone had seen the full importance of heterostylism.

In 1883, Alfred Russel Wallace wrote a tribute to Darwin (entitled 'The Debt of Science to Darwin’) who had died the year before. One such tribute appeared in 'The Century', an illustrated monthly magazine. As part of this article he included a summary of Darwin's work relating to this book (p. 428):

...
Wikipedia