That is a nice one! It jumped out from the bottom of a flowerpot into a space between railroad ties at my old cottage I lived a few years back. Within 3 years, it grew maybe 100 feet via underground runners.
A bit invasive but one of the best flowers for making flower leis. The leaves stink tho.
kevin
p.s. my preference is 1-YlangYlang;2-Michelia champaca Yel. 3-Stemmadenia littoralis;4-Rose Jasmine (grand duke)5-Eleagnus; 6-4 o'clocks then 7-the false pikake (your flower) then 8-J. officinale.