The worst smelling orchid is Bulbophyllum phalaenopsis (be sure to click on the "plant" link to get an idea of the size of this orchid). We picked this particular Bulbophyllum due to the sheer size of the plant and flower and therefore the amount of scent it produces. Many other Bulbophyllums produce the same carrion scent as this one, but are much smaller. Native to New Guinea, the pollinator is a fly which is attracted by the unpleasant odor. Last year, I found a live webcam of an opening flower -- the grower couldn't stand the smell but wanted to see the flowers opening!