Repeat after me: I will never use the following plants, and I will gently but decisively encourage friends and neighbors to follow my lead. Trust me, it's a resolution that takes pretty much NO effort, and is a small step towards creating a safer home and a better world.
OK, maybe not a better world. But it will certainly stop all of us from making it worse.
On second thought, perhaps this should be a group effort. I'll start the New Year's ball rolling, how 'bout you add on ...
Castor Bean Plants (Ricinus communis) with looks that kill
English Ivy (Hedera helix), invasive, unimaginative, overused and — oh yeah! — sometimes toxic
Tree of Heaven (Ailanthus altissima), perhaps the most Orwellian-named plant on the planet
Junipers, first and foremost, because life is too short.
Bittersweet (Celastrus orbiculatus), wanted dead or alive across North America ... and beyond ...