seed corn

from The Century Dictionary.

• noun Corn or grain for seed; seed-grain; ears or kernels of maize set apart as seed for a new crop.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Seed that is saved from one year's harvest for the subsequent year's planting, rather than being used to make flour etc.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun good quality seeds (as kernels of corn) that are reserved for planting