bunch vs bunch together

bunch is a noun but bunch together is not a noun.

Word	Noun	Adjective	Verb	Adverb
bunch	Yes	No	Yes	No
bunch together	No	No	Yes	No

As verbs, bunch and bunch together are synonyms defined as:

Other synonyms of bunch include bunch up.

bunch (noun)	bunch together (noun)
a grouping of a number of similar things
an informal body of friends
any collection in its entirety

bunch (verb)	bunch together (verb)
gather or cause to gather into a cluster	form into a bunch
form into a bunch