Possible Clues:

• In kitchen ban every herb that could be lethal?
• Plant a man carries in Parisian bar
• Poisoner next to be executed? Judge finally supports injunction
• Female outlaw having drug as source of poison
• This plant stores poison? Then ban edible contents
• Poisonous plant in the nightshade family
• Egg producer's embargo on eastern plant that's poisonous
• Common name of Hyoscyamus niger, a plant formerly associated with witchcraft
• Layer on diseased bean plant
• Plant that's death to poultry