The plants and herbs Geralt 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 and the climate change in the world with the witcher.

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.

Name	Description
Absenta	Artemisia absinthium, or wormwood, used in aphrodisiacs (also known as absinthe)
Acacia	"the acacias along the road to town"
Arenaria	"shoots of arenaria strewn with berries as red as blood"
Aspen	"you should burn juniper, broom and aspen in the fireplace"
Banewart	possibly deadly nightshade
Barberry	"at a green spot of barberry among the trees, heavy with bunches of red berries."
Belladonna	deadly nightshade that when mixed with hellebore, hemlock, sulfur, pitch and tacks, becomes poisonous
Bohun Upas	a tree with poisonous sap
Broom	"you should burn juniper, broom and aspen in the fireplace"
Celandine	a common plant with medicinal properties
Conynhaela	magical herb with healing properties, used with knitbone
Damiana	small flowering shrub whose blooms are used in aphrodisiacs
Eucalyptus	"greenish mush smelling sharply of eucalyptus"
Eyebright	found in alpine or sub-alpine meadows where snow is common, used to treat eye infections
Fastaim	"the meaty, thickly-veined leaves of fastaim"
Hawthorn	likely Hawthorn (Crataegus)
Hemlock	a plant that when mixed with hellebore, belladonna, sulfur, pitch and tacks, becomes poisonous
Hemp	"'A field of this size emits a strong aura against magic. Most spells will be useless here.'"
Honeysuckle	"breaking an overhanging twig of honeysuckle."
Hops	"'Those are hops — their pollen has the same effect.'"
Juniper	"you should burn juniper, broom and aspen in the fireplace"
Knitbone	magical plant with healing properties, used with conynhaela
Lungwort	used in decoctions said to help with one's haemorrhoids.
Mandrake	root with magical properties
Measure-me-not	"the crimson-golden ovals of measure-me-nots"
Melilote	"stretches of star-leafed melilote"
Monk's hood	also known as "wolfsbane", is a druids' herb.
Monkshead	possibly a type of lily, but also possibly a variant name for monk's hood
Mousetail orchid	"the tiger-striped petals of the mousetail orchid"
Pondblood moss	"pinnated pondblood moss huddled against stone blocks"
Puffhead	"compact balls of puffheads pouring out of huge flowerpots"
Raven's eye	"the glistening tubers of raven's eye"
Sand-spurry flybush	"huge pinnated leaves of sand-spurry flybush"
Sawcut	"the dark arrows of sawcuts"
Spurge	annual or perennial herb, woody shrubs or trees with a caustic, poisonous milky sap
Stramonium	is known as the hallucinogenic "jimsonweed"
True-love	Most likely: true lover's knot, Paris quadrifolia
Veratrum	interestingly also known as "false hellebore"

Subterranean plants

Name	Description
Reachcluster	"reachcluster, an antidote to every known toxin and venom."
Scarix	"The modest yellow-grey brushes peering from chests deeply sunken into the ground revealed scarix, a root with powerful and universal medicinal qualities."
Sewant mushroom	"In the shady part of the grotto bulged caps of the sewant mushroom, grey as the stones in a field."

Aqueous plants

Name	Description
Bitip	"Glass reservoirs full of gnarled rhizomes of the hallucinogenic bitip"
Cryptocorine	"slender, dark-green cryptocorines"
Hornwort	"vats full of hornwort"
Liverwort	"tanks covered in a compact skin of liverwort, fodder for the parasitic giant oyster."
Turtle duckweed	probably tiny green water plants which tend to grow on the surface of ponds

Organisms

Name	Description
Nematode	"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.
Phycomycete	a type of fungus
Algae
Moulds
Swamp lichen