valleylynn said: 
Wow, I'm not really sure what you just said Rick. But I will learn. 
It's analogous to the more common:
--- All azaleas are rhododendrons, but not all rhododendrons are azaleas.
Meaning: azaleas are a subgroup of rhododendrons.
So:
--- All cymes (cymous) are sympodia (sympodial), but not all sympodia are cymes.
Meaning: cymes are a subgroup of sympodia (that refer only to the inflorescence).
And:
--- All racemes (racemous) are monopodia (monopodial), but not all monopodia are racemes.
Meaning: Racemes are a subgroup of monopodia (that refer only to the inflorescence).
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Remember too, that in Latin, --ium is singular, --ia is plural. So:
--- monopodium, sympodium (singular nouns)
---monopodia, sympodia (plural nouns)
