“Naupaka” is the name of this plant in Hawaiian (I believe). Interestingly, there are two forms of the plant: a mountain form and a coastal form. In each form there is only a half flower that blooms, but in the mountain form it is said to form petals on the upper half and on the coastal form, the lower half. From this source I quote:
The Legend of Naupaka
It is said that two lovers, greatly devoted to each other, came to the attention of the Goddess Pele. Pele found the young man desirable and appeared before him as a beautiful stranger. But no matter what Pele did the lovers remained devoted to each other.
Angered, Pele chased the young man into the mountains, throwing molten lava at him. Pele’s sisters witnessed this and to save the young man from a certain death they changed him into the mountain Naupaka. Pele immediately went after the young woman and chased her towards the sea – but again Pele’s sisters stepped in and changed the young lover into beach Naupaka.
It is said that if the mountain Naupaka and beach Naupaka flowers are reunited, the two young lovers will be together again.