Excerpted From Botany Rutabagas are of the genus Brassica and family Cruciferae . The genus includes turnips broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, mustard, kohlrabi and others.
Rutabaga have bluish, thicker and smooth leaves.
Rutabagas are higher in total dry matter and total digestible nutrients than turnips. Neither is as high in sugar as the table beet, sugar beet or stock beet. Both turnips and rutabagas normally behave as biennials, forming seed the second year. He thinks it was introduced into this country after the beginning of the 19th century. It was then called Swedish turnip or Lapland turnip or rutabaga.