In the third verse, the text here is "There grow such sweet and pleasant flow'rs." "Sweet" is sung with a melisma (A Bb), giving a sense of degree (for the modifying "such"). In the fourth verse, the text here is "There evermore the angels dwell." Both "evermore" (D C A Bb) and "dwell" (D C) are sung with melismas, giving a sense of duration.
In fact, every "(for)evermore" in the fourth verse (one in each line) has this feature. I won't include notation for all of them, though.