Hoanglong,
That is a beautiful plant...and fantastic blooms!
I have one of these that was a gift 3 years ago...three p-bulbs without roots from a friend who had her son tear it out of a tree in her back yard. I cringed when she told me the story, and decided that I'd try and save it anyway. I wired it to a piece of cork, and about 4-5 months later, it grew a small 3 inch p-bulb. Since then, it has grown several more, each larger than the one before. The last 3 have been normal size with 3 leaves apiece. Hopefully it will be blooming next year.
Thamks for your post, and encouraging me that mine will be beautiful some day too!