Halves is a noun. It's the plural form of half.
"Two halves of the same walnut" comes from President Harry Truman's speech promoting the Truman Doctrine and the Marshall Plan.
Dicot refers to the seed which has two halves the two leaves associated with the seed are part of the halves.
part of speech
The part of speech for this particular word is a noun.
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
The part of speech for "explicit" is an adjective.
The part of speech for "twirl" is a verb.
The part of speech for "unfamiliar" is an adjective.
The part of speech of "came" is a verb.
The part of speech for "lecturer" is a noun.