In my library alone there are at least a hundred books on the subject of medicinal plants. There are thousands more out there in the world. Just as plants became a sustaining factor for the existence of life on earth, medicinal plants were the basis for most medicine to date.

Herbal medicine in Earth's history was a hit-or-miss occupation. Five thousand years ago they were putting moldy bread (penicillin) on wounds ... twenty years ago they were prescribing peach pits containing cyanide to cancer patients (no, it didn't work). Nothing here is going to be solely based on fact--in other words, keep this in your game only don't try any of this on real-life situations.

Emergencies

Most herbal medicine for use in-game can be divided into two categories: Instant and Not. Since most campaigns won't involve illnesses that require long-term treatment, this article is going to predominantly be about emergency herbal medicine out in the wilderness.

Most outdoorsy types will have a working knowledge of the emergency herbal aid of their area, passed to them from their experts in their field. Any characters that were raised indoors or in the city would carry salves or ointments out on their adventure. More on salves later.

A character in the woods gets slashed with a knife, bitten by a wolf or a snake, or burned by a spell involving fire. Now a player can keep rolling dice until he or she can announce the healer has returned x many hit points to the wounded warrior, or the dice can take a back seat to playing and the healer rips some leaves off a plant and binds them to the wound.

Most traditions believe in not wasting magic when a mundane solution can work just as well, and anyone who knows some healing spells, probably has also been shown some tricks as well. Also, a healer who staunches a wound with some plants and then tries to heal it with a spell should have an easier time than one who has to deal with a gaping hole gushing blood. A gamemaster should either increase the healer's likelihood of making the initial roll, or add a +1 or +2 bonus onto the effects.

What to use?

It is said that to treat an insect bite, wound, or rash, take three different leaves and rub them on the wound. This is because all green leaves contain chlorophyll and this substance is itself an antiseptic. Most leaves also contain tannic acid, which is astringent and helps staunch bleeding. For any wound the characters receive, leaves should be the first thing anyone grabs.

While it's true that some leaves are poisonous and cause rashes, most wilderness-going adventurers in their native region can identify and avoid these plants. A gamemaster should slow down or stop removing hit points from a wounded character once a handful of crushed leaves is bound to the wound. These wounds are also less likely to fester and become infected, leaving the character injured, but not incapacitated by fevers and loss of movement.

The next best thing to leaves in case of injury is bark, wood, and resins from various trees. The essential oils from most woods are antiseptic, even killing airborne diseases. Resin is the quickest to collect, using a knife to slash the tree’s trunk and then gathering the sap. A character can also chip off pieces of the trunk, set them in water or boil them and then use the water/pulverized wood as a poultice.

Roots usually have stored concentrated active compounds. This is where you usually find the most potent treatments and most deadly poisons. A healer may be able to identify a root by its aerial parts, but there is also a risk of mistaking one plant for another or finding a root without its identifying flower or leaves. Also, in winter and early spring, roots will be deep under the ground without any aerial parts to identify.

Flowers are usually used for much subtler treatments, or used to soften the skin and soothe burns and wounds rather than heal them. They can be used to reduce some of the pain of an injury. Seeds, fruits, and nuts mostly contain nutritional substances, enzymes, and stimulants and although some are useful as painkillers and wound healers, they are more likely to be used by the characters for long-term treatment.

If the player announces in any given area that the healer is going to grabs some leaves or bark and try to staunch the bleeding, a gamemaster can roll to see how likely there is a plant in the area with better chance of doing the job. The gamemaster rolls his die, choosing high or low for good to bad: hitting the average just means the chlorophyll or resin does its normal astringent, antiseptic job. Closer to the success end of the scale and the character selects a plant that is known for its wound-healing abilities. Closer to failure and the plant does less, with a critical failure causing poison damage to the poor victim.

Types of Emergencies

Slashing injuries

Number uno on this list is wound binding/healing. Thankfully, this is where plants are best used. Most plants are applied as a poultice for these types of ouchies, crushed and applied directly, or mashed up, placed on a cloth, and then applied.

Tundra/Alpine: Balsam Fir, Alpine Forget-Me-Not, Water-Arum
Mountains: Ground Pine
Taiga: Tamarack
Savannahs: Eucalyptus, Centella Water-retentive Temperate: Purple Loosestrife, Butterbur
Warm Coastal Swamplands: Cajeput
Bogs/Moors: Curved Leaf Moss
Temperate Coastlands: Sea Buckthorn, Sea Holly (root poultice)
Chaparrals: Hyssop, Greater Periwinkle, Yarrow, Hypericum
Hot Arid Conditions: Neem, Aloe
Northern Grasslands: Harebell (root), Woolly grass, Giant Puffballs
Temperate: Bullace, Pangium, Poplar, Oak, Witch Hazel
Temperate High Altitudes: Paper Plant
Moist Woodlands or Meadows: Bugle, Lady’s Mantle, Bistort
Drought-ridden areas: Pagoda Tree
Rocky Soils: Rue, Polygonatum, Stonecrop, Woad
Tropics: Derum, Patchouli, Sugar Cane
Wasteland: White Dead Nettle, Plantain, Silverweed

Sometimes wounds get infected, and these require more potent treatments. It stands to reason that most characters with an infected wound will find professional help or use a first-aid spell, but sometimes this just doesn't happen. The characters could also come upon an NPC with a festering wound and, again, a wilderness-oriented character may be expected to know something of fixing it. The plants listed above will certainly help keep the infection from spreading further thanks to their antiseptic qualities, but the plants below are available in large quantities in their climes and have extra potential.

Arctic: Sorrel
Northern Woodlands: Bloodroot
Damp Woodland: Knotted Figwort, Adder's Tongue
Tropics: Muskseed
North to Tundra: Burdock
Wastelands: Common Ragweed, causes 90% of allergies in America so make a check against health for allergic reaction.

Other Traumatic Injuries

Characters receive a lot of injuries that don't bleed, including bruises, welts, swellings, and broken bones. They're lumped together here, but comfrey is really the only medicinal plant that is known for speeding the knitting of broken bones.

Swellings/Bruising:
Damp Grasslands, Riverbanks: Comfrey
Wastelands: Mignonette
Chaparral: Bay
Temperate to Alpine: Burdock, Rue

Many of the plants above used for open wounds can also be used on burns to keep infection at bay. Raw potatoes (Everywhere), Aloe (Arid), Eglantine (Temperate), and Muskseed (Tropics) are considered especially useful for burns.

Bites and Stings

While not a medical emergency for most, a GM could probably apply these types of histamine-raising injuries to giant insect monsters as well.

Dry, thin soil (Rocky ground): Houseleek
Chaparral: Alecost, Basil
Hot Swamplands: Wild Yam
Forests: Maidenhair Fern
Savannahs: Baobob leaves
Salt Marshes/Wastelands: Purple Orach
Fields: Onion bulb
Tropics: Pineapple Leaves (spider bites)
Monsoon Regions: Turmeric

For most animal bites, a healer with magic is probably necessary, but in the event that one is not available, a GM could pump up the potency of one of these herbs as well. Temperate: Annual Chamomile, Catsfood (poisonous reptile bites), Horehound (dog or snakebite), Sea Holly (snakebite)
Temperate Wed Woods: Maidenhair Fern (centipede bites, insect stings, even snakebite)
Tropics: Matico (leech bites)
Warm Temperate: Ironwood Tree (mosquito bites to snakebites)
Wasteland: Wormwood (bites, including sea-serpent bites)
Wet Tundra: Water-Arum (snakebite)

Poison Control

Several plants are claimed to be antidotes or treatments to poisoning. Certainly the characters could use some of this information after getting kicked out onto the streets after a night of feasting and carousing.

Honeysuckle flowers and stems (berries poisonous), can treat food poisoning; found in Oriental regions.

Soya: Warm temperate zones. Soybeans. Treat food poisoning
Milk Thistle: Protects liver from poisons, including deathcap mushroom.
Galangal: Food poisoning (tropics)
Annatto: Tropics, Antidote to Prussic Acid poisoning (from cassavas, cherry pits, etc.)
Purple Loosestrife: Food poisoning (along temperate riverbanks).
Tea: Food poisoning (maybe available a lot in your realm)
Black Drink Plant Berried emergency medicine causing vomiting in cases of poisoning (temperate to northern).
Levant Nut: Itself poisonous, this vine is used as an antidote for morphine poisoning
Clematis: Used for alcohol poisoning (temperate).

Other Quick Fixes

These are plants that have remedies attached to them that may be useful to your campaign.

Wild Cabbage: Antibacterial, speeds tissue growth on wounds, poultice of raw leaf eases pain of muscle strain, sprains, headache. Can be used for internal bleeding. Regular cabbage grown in garden can be used in same way.
Fleabane: Stops hemorrhaging in lungs and throat, good externally as well.
Snake Tongue Grass: Aerial parts treat swelling, inflammation; snakebite, appendicitis, infected skin, traumatic bruises (wet ditches).
Khella: Morning-after contraceptive (arid conditions).
Fig Tree: Remedy for mad dog bites and other venomous beasts.
Mulberry: Bark heals intestinal wounds and snakebites (temperate).

Next Up: Plants as Medicines, or Ow! Is there a Leech in the House? Part Two (Getting the Professionals)