Baret was an accomplished botanist herself, although her expertise was self-taught. The book credits Baret with the "discovery" of the bougainvillea plant, which Commerson named in honor of the expedition captain, Louis-Antoine de Bougainville. While Commerson was laid up with leg ulcers, Baret went ashore alone collecting plants and insects near Rio de Jainero. She returned to the ship with several boughs of the showy vine as well as seeds, which ultimately led to the plant's introduction to the rest of the world. Ridley speculates that Baret collected the plant because she thought it might have some healing properties with which she could treat Commerson's nearly gangrenous leg. Turns out that the plant has no such medicinal properties, but has been a success as an ornamental in tropical and sub-tropical gardens.
Baret was an accomplished "herb woman", familiar with plants in her native France and plant-based remedies for various ailments. The beginning of the book makes the point that much of the botanical (and associated medical) knowledge of the time resided with such women. Men who enjoyed professional positions as professors of botany or medical doctors got much of their information about plants and their properties from these female experts (typically in secret). Apparently, many of these male professors and doctors never bothered to go out in nature to observe plants, preferring instead to study about them in books and classrooms. The more enlightened ones recognized the value of this knowledge that had been painstakingly gathered over generations; so they regularly visited herb women to get information or to purchase dried herbs for use in their medical practices. This is how Commerson apparently became acquainted with Baret, who ultimately became his housekeeper and lover.
Baret never received credit for the discovery of bougainvillea, nor for anything else, including surviving a grueling two-year trip around the world with a boat load of suspicious seamen. She hid her feminine physique under tight bindings around her breasts (which led to a horrendous case of eczema) and a loose, bulky sailor outfit. Rumors still broke out among the seamen about a woman being on board (naval law prohibited women from sailing on any vessel). She apparently countered this rumor with a clever story about being a eunuch, which played into the fears of every man on board, who immediately recoiled from any further investigation into Baret's gender (although not all ship occupants were so convinced).
That's about as far as I've gotten in the book. My impression is that Ridley has done extensive research, but has filled in a lot of blanks based on deductive reasoning and educated guesses. It's a fascinating story and one that makes our modern trials and tribulations as women in science look pretty minor. Perhaps I'll have more thoughts on that after I finish the book.