The "sprouts" from Section 29 must have been grass sprouts, because now Whitman is talking about "leaves of grass" again.
(As you read the poem carefully, you'll notice how things connect in very subtle and unexpected ways. The poem began with questions about grass, and now the speaker returns to the growth of grass following a discussion of reproduction and growth.)
He creates another list of natural things to explain how they are better than any kind of human creation like statues or machines.
He says that things can never truly escape from him. There's no escape from Whitman! He can make things that seemed distant close again.
He creates yet another list of distant things, to show how their distance is "in vain." These things include everything from "shyness" to migratory birds. He'll stalk those birds on jagged cliffs if he has to – they're not getting away from him.