rootstock

Plural: rootstocks

Noun

• a horizontal plant stem with shoots above and roots below serving as a reproductive structure
• root or part of a root used for plant propagation; especially that part of a grafted plant that supplies the roots
• A healthy and vigorous-rooted plant that is used in grafting, most commonly as a sound base to support a scion that bears desirable fruit in orchard culture.
• The necessary basis for something to develop.

Synonyms

rhizome, rootstalk