a poisonous plant is dangerous
poisonous_plant is plant. poisonous_plant is not plant. aconite is poisonous_plant. poison_ash is poisonous_plant. dogbane is not poisonous_plant. aconite is not poisonous_plant. poisonous_gas is toxic_substance. poisonous_gas is not toxic_substance. poisonous_gas is chemically_harmful_substance. poisonous_gas is not chemically_harmful_substance.