Blueberries

English is really a fine language for poetry. It’s got a heavy stress — much heavier than the more evenly settled syllables in French or Italian — and that means that you needn’t always count the syllables in an English line. What matters for a lot of English poems is not the number of syllables, which can vary, but the number of STRONG BEATS, with one or two (and in folk songs, even three) light beats in between. We can call it ACCENTUAL meter.
A lot of English folk songs work like that. Think of the merry sea chanty:

WHAT shall we DO with a DRUNK-en SAIL-or?

And the answer may be:

GIVE him a DOSE of SALT and WA-ter!

See, you get four strong beats per line, and the syllables in between fill up the same length of musical time, so that if you’ve got two, they’re like eighth notes to the strong beat’s quarter note, and you have to pronounce them twice as fast, and if you’ve got three, well, three times as fast. So it happens in this sort of song, the more syllables you have, …