絲瓜 is the term I use to describe the two different varieties of loofah that are eaten.

I've edited this into the post — thank you!

Also, I think it's interesting that you consider the radical of 瓣 to be 瓜, as my first thought would be 辛. Then I checked the dictionary and found 瓣 under both radicals. :D

I was blindly trusting CantoDict :) I checked my dictionary, and it has 瓣 under both, too!