I'm not quite sure if @hjon knew the can of worms he was opening up when requesting Lo, How a Rose E'er Blooming for today's carol. The truth is, I have been avoiding covering it, even though it is one of my favorite musical compositions, since the history behind the hymn can be thought of almost as a literal "war of the roses" (between Catholics & Protestants).
The original German version of the hymn Es ist ein Ros entsprungen emerged in the 1580's with the documented inspiration for the words coming from the Song of Solomon 2:1 - "I am a rose of Sharon, a lily of the valleys". Here is the literal translation of the German:
A rose has sprung up, from a tender root. As the old ones sang to us, its lineage was from Jesse; and it has brought forth a floweret - in the middle of the cold winter - right upon midnight.
The rosebud that I mean (of which Isaiah told) is Mary, the pure, who brought us the floweret. At God's immortal word, she has become borne a child remaining a pure maid.
The floweret, so small, that smells so sweet to us; with its clear light dispels the darkness. True man and true God! He helps us from all trouble, saves us from sin and death.
Between the scriptural dedication and word-for-word translation, it is clear that the emphasis (the rose) for two-thirds of the original carol is Mary, the mother of Jesus, not Jesus himself. As you can imagine, this did not sit well with Protestants, but they must have really enjoyed the hymn since the first adaptation (in German) came in the early 1600's re-dedicating it to Isaiah 11:1 - "There shall come forth a shoot from the stump of Jesse, and a branch from his roots shall bear fruit." - making Christ the rose and helping to forge the Baker translation which the majority of us sing today.
Without going into the gory details, there was a back-and-forth for a quite a while between Catholics & Protestants, each group emphasizing their version of the hymn and trying to influence adoption of it and also various translations.
I do not know what amount of effort was truly put into this "war," but I do know that for every hour of debate over Catholics' supposed Mariaism (spent by Protestants) and every counter debate over Protestants' Biblical idolatry (spent by Catholics) there is a homeless person shivering for one more hour in the cold from a foreclosed house, a family with a newborn baby struggling to make ends meet and lost souls turning away after seeing a struggle between those who should be brothers.
In any of its forms, this carol ultimately leads us to the simultaneous full humanity and full deity of Christ (John 1:14), the Light of the World (John 8:12), who died for our sins (1Cor. 15:3) and who's Spirit is with us every moment to help us on our journey home (John 14:26). I can think of no better place to journey, in song or in daily practice.
Finally, the truth is that we should rejoice with the likes of Luther, Calvin, Wesley and others who acknowledge the profound role given to and accepted by Mary, one of Scripture's most profound demonstrators of humility, personal sacrifice and listening to & obeying the Will of God. We would do well to follow Mary's example, all the time keeping our eyes fixed on Christ (Phil. 3:14).
Lo, How a Rose E'er Blooming
Lo, how a rose e'er blooming,
Isaiah 'twas foretold it,
O Flower, whose fragrance tender