Sentence:  On the tip of each corn kernel is a <WSD>hilum</WSD>, collectively known as the "black layer," where it is attached to the cob. While corn is growing, nutrients are being transferred from the rest of the cob to the kernels through the <WSD>hilum</WSD>. 
Meaning of the word marked with <WSD> tags:  The eye of a bean or other seed; the mark or scar at the point of attachment of an ovule or seed to its base or support.