Answer: The author wants to use imagery as a way of portraying what the leaves of the tree may look like.
Step-by-step explanation:
By looking at what the author wrote we can conclude that the leaves are pointy and dense. We conclude they are pointy because he describes them as "bayonet pointed" aka sharp as a bayonet is a knife.
He uses "fence of daggers" aswell to show they are pointy, yet by referring to them as a fence we can conclude they are dense and impassible because like a fence, we cannot pass through the leaves.