Yuzuriha / Yuzuri-ha
Maybe the most interesting leaf behavior is called Yuzuriha or Yuzuri-ha. According to Japanese legend, Yuzuriha means that the old leaves are replaced by new leaves in the new season, to "take over" or "take turn." and only dropping after the new leaves emerge, so there is no interruption of the tree’s foliage.
It's noted that the new leaves give thanks to the old leaves for their kind nourishment during the winter. "Compassionate" is a term also used for these trees. Mixican white oak is one of my favorites in this category but very hard to find unless you go the annual plant sale at Steven F. Austin in Nacogdoches. http://www.sfasu.edu. That's where I got mine. Also available on-line.