Veronia Noveboracensis known as New York Ironweed is the one I am familiar with. Most of the Veronia species contain Vernolid A which has been shown to inhibit cincer. V Noveboracensis does not contain as much as the others. This is the only species I have seen in person.
Veronia Amygdalina and V. Cinerea were the most potent of the Veronia species.
V Amygdalina reduces oxidative stress and helps with diabetes.
V Cinerea can help with nicotine addiction.
V Amygdalina can reduce oxidative stress.
V amydalina is hepaprotective.
Have not seen toxicity studies on the other Veronia species but V. Cinerea shows no toxicity.