Here's the most wide spread pitcher, even reaching Canada. With the pollination syndrome described yesterday, some wondered if this genus is self-pollinating. If it drops pollen onto the lobes of the stigma, and bugs crawl through on their way to the anthers, isn't it necessarily so? Some pitchers do self pollinate, some don't. The stigmas where the pollen is accepted are at the outer points of the green lobes you see here. So the pollinator passes them before it gets to the free pollen of the flowers. But things are sloppy, and some flowers do end up self pollinated. I don't know for sure how species that don't self pollinate prevent it. A good guess would be that they don't produce pollen until their anthers are no longer active.