"bracken by the load,..."
See in text (Text of the Poem)
The noun “bracken” refers to ferns. It can suggest a single plant or an entire layer of fern growth, the latter of which is most likely the case here. The description of the bracken as “withered” points to the broader condition of terrestrial life, suggesting its harsh nature and cycles of decay and renewal. Such earthly life stands in stark contrast to the heavenly states glimpsed briefly at various points in the poem.