Those two plantains sure have different flowerstalks! The seeds of the broadleaf plantain are so much bigger and it's satisfying to strip them off that stalk, lol.

These plantain plants are closely related to commercially grown Plantago species. Those farmed Plantago are grown for their seeds to produce Psyllium -- the working ingredient in Metamucil! So those seeds are a "dietary fiber", for sure! It's great having the wild relatives to use for food!