The above poem has a very unusual and complex internal rhyme scheme. Here's another copy of the song arranged to emphasize the meter and rhyme:

My love to my bride / with dear caresses,
And pride, / shall ever be shown,
Each virtue most rare / her soul possesses,
And fair / and sweet has she grown.
My thoughts used to rove / in boyish folly
Ere ever her love / I'd known,
But now I'm her own, / my heart is wholly
My darling's alone, / alone.

Where woodlands are green / with trees well nourished
A scene / of beauty to view,
I found with delight / one stem that flourish'd,
Of bright / and beautiful hue:
That bough from above, / desiring greatly,
Unto me with love / I drew;
None else could that tree / have mov'd so stately.
'Twas only for me / [that] it grew.

In the version that lesley posted above (which was apparently copied and pasted from http://www.contemplator.com/folk/maribhan.html), the pattern breaks down in the last few lines. I have restored what I think was the intended pattern by moving a few words around. Now it scans perfectly, but I'm still a bit dissatisfied with the result. "So stately" would make more sense modifying "tree" than "mov'd".