Heard it through the grapevine
The above expression is a way of saying something you told another actually came from an informal source. The saying has an interesting origin. It first began in reference to the telegraph. In 1844 Samuel Morse provided the first public demonstration of the telegraph by sending a message from Washington D. C. to Baltimore. It became popular as a rapid means of communicating a message over long distances. The term “telegraph” is the combination of the two Greek words “tele” and “graphein.” .The word “tele” means far; and “graphein” has reference to a written message. Thus combined as telegraph it means a message sent from a far distance.
But someone may be ready to say, “What is the relationship of the telegraph to the expression “Heard it through the grapevine”? Not long after the telegraph was invented the expression “grapevine telegraph” became commonly used in reference to it. The expression was first found in an American dictionary in 1852. The telegraph lines used to carry a message over a distance were described as vines. It made an indirect reference to people who lived among grapevines, the poor folks.
Again, the expression: “Heard it through the grapevine” means I obtained it from an informal source; not from an officially, or directly from the person or persons in consideration. Negatively, I didn’t hear it “straight from the horse’s mouth.”