Aerangis citrata - the flowers are slightly yellow in color.

 Aerangis citrata
     This species is native to Madagascar. It is likely the most popular of the Aerangis species for several reasons: a blooming sized plant is quite small—a bit larger than a true miniature, the flowers are rounded and all face out like on a well-bloomed phalaenopsis and they’re quite easy to grow. The flowers are slightly yellow in color, hence the name. Our first plant had one flower spike on its first blooming, two on its second, three spikes on its third blooming and so on!!! They’re easy to bloom—sometimes more than once per year—and very rewarding.