five head of cattle v.s. five heads of cattle

five head of cattle (said by ranchers)
ten stem of roses (said by florists)
three pair of pants (or pairs)

Note that the preceding measure words are singular in form. If they were plural, the first two phrases would have different meanings.

I wonder what the different meanings would be if plural is used. Can someone please explain?
Thank you.

five head of cattle - five animals.
five heads of cattle - just their heads, no bodies.

ten stem of roses - ten flowers.
ten stems of roses - just the stems, no flowers.

Incidentally, I’ve never heard anyone refer to two or more pair of pants, always two or more pairs of pants.

Thank you, Beeesneees.
But would the following become ambiguous?

one head of cattle ==> Is the body included?
one stem of rose ==> Is the flower included?

If they refer to the first meanings (body is included; flower is included), how to express the second meanings?

They are not ambiguous in the contexts given. Theuy are specialist terms.

My question is how to say a single one head of cattle without its body? I asked because I thought we cannot say “[color=red]one heads of cattle,” can we?

I just found another way to say:
a/one cattle head
a/one rose stem

No -
one head of cattle - one animal
one stem of roses - one flower
as used by the rancher/florist)

one cow’s head - no body
one rose stem - no flower
the ‘different meaning’.