Definition of "rootstalk"

All these species are climbing, briery plants, having long slender roots, which proceed in all directions from a common rootstalk or rhizome.

1868, George Bacon Wood, A Treatise on Therapeutics, and Pharmacology, Or Materia Medica, Philadelphia: J. B. Lippincott & Company, page 432

For Theophrastus insists that the scion's relation to the rootstalk is not essentially different from that of any other plant's relation to the earth. The rootstalk simply provides nourishment, just as the earth does, while the formation and growth of the scion are both due to the power of the scion itself.

2016, James Wilberding, Forms, Souls, and Embryos‎, Routledge