Swollen. (Anglo Saxon, bolla, a bowl.) Hence “joints bolne-big” (Golding), and “bolne in pride” (Phaer). The seed capsule or pod of flax is called a “boll.”
“The barley was in the ear, and the flax was bolled.”- Exod. ix. 31.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894