The plants and herbsGeralt can gather and use in The Witcher games are not unique to the game. Even in the first book translated to English, The Last Wish, there are mentions of numerous plants.
In the short story "The Witcher", a couple are mentioned as ingredients of potions, but most of the mentions occur in the sixth part of the framing story, "The Voice of Reason" where Nenneke discusses the plants found in the grotto with the witcher and climate change in the world.
Some of them can easily be matched with the plants found in the game, but not nearly all of them. A good number of them are also plants found in the real world.
a genus of flowering mostly herbaceous perennial plants 0.3–1.5 m (0.98–4.9 ft) tall, but some are annual plants and a few are shrubs up to 3 m (9.8 ft) tall
most likely deadly nightshade, but possibly any of an economically important family of flowering plants. Certain species are universally known for their medicinal uses, their psychotropic effects, or for being poisonous
"The modest yellow-grey brushes peering from chests deeply sunken into the ground revealed scarix, a root with powerful and universal medicinal qualities."
"clusters of nematodes", in the books, it is not exactly clear is these are meant to refer to plants or animals, these are usually tiny wormlike organisms and not plants.
a composite organism consisting of a fungus (the mycobiont) and a photosynthetic partner (the photobiont or phycobiont) growing together in a symbiotic relationship