Well, flowers are basically the elaborate stage settings for the sex organs of plants. In the case of orchids, the blatant carnality of the flowers is immediately evident, even to the untrained eye. George Bernard Shaw compared orchids to courtesans, Marcel Proust associated the plants to harlots and homosexuals, while John Ruskin considered orchids to be prurient apparitions. Orchids are all of these things, and much more. They can put on lascivious displays with their gaudy colors, intoxicating scents, veined pouches, erect curving shafts, glistening pink labial folds and inviting orifices.
Orchids have some of the most immodest and outrageous flowers in the plant kingdom.
But apart from how they smell, and what they look like, they have always been associated with sexuality. This is a reference to the paired, underground tubers that are found on many terrestrial orchids. Learned scholars in the middle ages even argued that orchids grew from the sperm of wild animals that had fallen to the ground. Even today, Shalimar, Jicky, and many other famous perfumes use vanilla to make the finished fragrance more lush and sensual. The book has entire chapters devoted to the subject of why these flowers are so sexy.