As the article says… one of the frequently made “mistakes”
Frankly, I can understand confusion, when the French is flowing much too fast. (I’ve been there, done that…)
Marrons can be delicious - and come from the Châtaigne tree. (chestnut)
Conkers/horse chestnuts are poisonous and come from the Marrons d’Inde tree. (marrons???) 
