'Kernel' in the Bible

“For behold, I am commanding,And I shall shake and sift the house of Israel among all nations [and cause it to tremble]Like grain is shaken in a sieve [removing the chaff],But not a kernel [of the faithful remnant] shall fall to the ground and be lost [from My sight].

The seed you sow is not the body (the plant) which it is going to become, but it is a bare seed, perhaps of wheat or some other grain.