There are a wide variety of toxic plants with have a wide range of symptoms, and some can be fatal. Sometimes a part of a plant can be edible while another part is not, e.g., you can eat the flower but not the stem. In others perhaps they are only edible when cooked a certain way etc.
In fact, there are so many plants and so many variables that for a majority of them, no specific treatment exists.
As a rule, do not touch, and especially do not ingest any plant that you are not 100% sure about.
Treatment for Toxic Plant Contact
Treat symptoms.
Use local knowledge.
For skin irritants, e.g., poison oak:
Thoroughly wash area.
Use alcohol to neutralize.
If ingested:
Take the following history:
Ø Amount and part of plants ingested.
Ø Initial symptoms.
Ø Method of preparation, e.g., drying, cooking, boiling.
Ø Number of persons who ate the same plant, and their symptoms.
Ø Time between ingestion and onset of symptoms.
Ø Time of ingestion.
Do not induce vomiting unless it is a specific treatment, but be prepared for it as a symptom.
Activated charcoal is preferable. If that is unavailable, mix tea and wood charcoal (not briquettes) and add milk of magnesia if available.
Note: be extra careful of passing on the toxin, e.g., touching your mouth or face after handling, giving rescue breaths.
You can learn more about plants at SurviveTravel.com/Useful-Plants.