Well, you gotta love word geekery.
As a college student learning Gothic, the now-extinct language that is the oldest Germanic language for which we have any substantial documentation, the teen-aged J. R. R. Tolkien—himself an good Hwiccan lad—was not content simply to learn the language.
Of course not. Tolkien being Tolkien, he composed poetry in Gothic as well, using (of course) the old Germanic four-beat alliterative line.
Bagmê Blôma, “flower of trees” (this would be “Beams' Bloom” if we were translating into English cognates) is Tolkien's hymn to the “mistress of the mountain,” Lady Birch, the very arboreal embodiment of Spring.
Scroll forward some years. Linguist and Tolkienist Eric Kinsepp translates Tolkien's Gothic into Modern English, thus giving us words singable to a tune by 20th century English composer George Mantle Childe.
And lo: the witches sing this song at Ostara to this very day.
Sometimes even in Gothic.
Flower of Trees
On glorious branches, glittering
and pale green as she grows,
the birch tree bears her lovely leaves,
the flower of flowering trees,
fair of hair and lithe of limb,
the mistress of the mountain.
The winds now stir and gently call,
she lowers her limbs in play.
Sleek and straight and white of bark,
she utters in a trembling tongue
—great mystery, bright token she—
a blessing on my people.
The twilight sky, obscured by cloud,
grows bright again with lightning;
but standing strong and faithful
while her lovely leaves take flight,
the birch will wait there, bare and white,
still mistress of the mountain.
J. R. R. Tolkien, Bagmê Blôma
Translated from the Gothic by Eric Kinsepp
Tune: Lazy Sheep, Pray Tell Me Why, by George Mantle Childe (1949)
Based on an old French air