And yet all around me is that odor that I have not smelled since I was eleven, but have never forgotten—have dreamed, more than once. Then I pull myself up the bank by a gray-leafed bush, and I have it. The tantalizing and ambiguous and wholly native smell is no more than the shrub we called wolf willow, now blooming with small yellow flowers.
The author is reminiscing of his childhood, and the smell of the wolf willow is the thing that he remembers from his childhood. Its the smell of the wolf willow what reminds him of home.