半天妖 / 半天腰 / 半天夭 / 半天鹞
All four characters for 'yao' circulate. 半天腰 ('halfway up the sky') is usually explained by the bush's position partway up the third peak of Sanhua Peak (三花峰). One legend says a hawk (鹞) dropped the seed there, giving 半天鹞, which was later written with the homophones 夭 and then 妖 ('demon'). 半天妖 is now the dominant trade spelling. English Wikipedia uses 半天腰, so the 'Half Sky Demon' and 'Halfway to Heaven' translations rest on different characters.