Easton's Bible Dictionary (1897)
(Ex. 9:31), meaning “swollen or podded for seed,” was adopted in the Authorized Version from the version of Coverdale (1535). The Revised Version has in the margin “was in bloom,” which is the more probable rendering of the Hebrew word. It is the fact that in Egypt when barley is in ear (about February) flax is blossoming.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
BOL'LED . Ex 9:31. The expression flax was boiled means that it was podded or nearly in a state to be gathered, and of course the loss of it was much more severe than it would have been at an earlier stage of its growth.