lyoucobryum, and where the you comes from
heard as lyoucobryum
spelled leucobryum
From eucalyptus and Europe, where eu really does say yoo. Here it is leucobryum.
What the ear did
The reader is generalising an English habit onto a Greek stem that does not take it. In every leuco- word in English the sound is a plain oo, and the spelling stays eu regardless.
L-E-U-C-O-B-R-Y-U-M
The full entry for leucobryum covers the name itself.