How to use IndexOf()

  Hi all i have a quick question,why does my code not able to return "Cactaceae" it will return the whole sentence instead "Cactaceae, Cactus"?

  string plantName = "Cactaceae, Cactus"; 

  int stringPosition = plantName.IndexOf("Cactaceae"); // to return Cactaceae

  string commonName = plantName.Substring(stringPosition); //to return Cactaceae

  Console.WriteLine(commonName);//to return Cactaceae