From Goodreads:

An audacious, comic fantasy, satirizing the ways of society, and parodying the mannerisms of certain popular writers. Gay men in turn-of-the-century Paris wore green carnations in their buttonholes. On a visit to Egypt in the winter of 1893-1894 for his health, Hichens met Lord Alfred Douglas and was introduced by him to Oscar Wilde, who was already the most renowned author of his age. Hichens returned to England and wrote The Green Carnation---epigrammatic and keenly satirical in tone---as a parody of Wilde's style, with Douglas burlesqued as Reggie Hastings and Wilde portrayed as Esme Amarinth. The book was a huge success, and it launched Hichens' fiction-writing career. Robert Smythe Hichens (1864-1950) is also the author of The Garden of Allah. Although at the age of seventeen he wrote a novel which was actually published, he seems to have been most bent on a musical career; but he wearied of music and turned to journalism.