Tubers form at the base of roots and store energy in the form of starch to support new stem growth for the plant. Examples of tubers include Jerusalem artichokes, jicama, yams, and potatoes.
JERUSALEM ARTICHOKES: Jerusalem Artichokes are not associated with either Jerusalem OR Artichokes. Helianthus tuberosus aka sunroot, sunchoke, earth apple, or topinambour, is actually species of sunflower native to eastern North America. This tuber a source of iron, almost on a par with meat, but without any fat content.
JICAMA: Jicama is actually a member of the legume family. It contains important vitamins like folates, riboflavin, pyridoxine, pantothenic acid, and thiamin, along with several important minerals. They should be used sparingly because they are high in carbohydrates.
YAMS: These are NOT the same as Sweet Potatoes (SPs) and are not as packed with vitamins as the SP. Yams are higher in phosphorus, potassium, Vitamin C, folate, and Vitamin K but the SP is a better choice overall.
POTATOES: White potatoes are mostly water and carbohydrates (mostly from starch). Raw they do provide a good helping of B6 and Vitamin C, but those are usually lost in baking/cooking. Bottom line is they aren't something we feed our birds.