I thought that "slow" would be the adjective, but I don't know what it's modifying...

I don't think there is an adverb in the sentence. Adverbs have to modify verbs, adjectives, or other adverbs. The only choice would be "Japanese" because it modifies "maple" which modifies the implicit "tree" but I think that's a stretch because the whole noun is "Japanese maple tree"

The - article
Japanese - adjective (or adverb?)
maple - adjective (or noun?)
is - verb
slow - adjective describing Japanese maple
to - infinitive
shed - verb
its - adjective for leaves
leaves - object

Good luck

There seems to be no adverb in this sentence. Japanese is an adjective of the noun maple. There is no other word that enhances the effect of anothernoun/adjective/adverb, and so this sentence has no adverb.

There is no adverb in that sentence. 'Slow' is an adjective.

If the sentence were re-worded to "The Japanese maple sheds its leaves slowly" then 'slowly' would be the adverb.
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