African species, Bulbophyllum falcatum. It quite a varied species, I was lucky with this one because the individual flowers are very yellow. Most falcatums are more a muddy less conspicuous yellow. The flat swollen rachis which each of the flowers are attached to. That is a characteristic only found in African bulbophyllums and this section falls under the name Megaclinium.
Great plant! I had one...until it got too big for my space. If you can get a close up of the flowers...they look like little monsters w/their mouths wide open. Very cool! Good job growing it.