Sentence:  Basked in the sun, or plunged into thy stream's    [1.20] / Alternate, all a summer's day, or coursed / Over the sandy fields, and dashed the flowers / Of yellow <WSD>grunsel</WSD> ... 
Meaning of the word marked with <WSD> tags:  Variant of groundsel, any of several species of "Senecio", a genus of the daisy family.