[NepNut]

Yes, I also came to the same conclusion why the pitchers developed resting on something to support it's weight will tends to be bigger. I think it's a natural reaction from the plant if the pitcher is develop without somekind of support, it'll reduced it's weight by producing smaller pitcher.

Actually, it's not only lower pitcher, same thing happen with upper pitchers too... If the tendril can grab on to something, the upper pitchers develop that way will also tends to be bigger compared to the ones that the tendril is dangling freely (if develop at all)... this is what I observed personally.