mr. trench said:

The Chinese eat a vegetable called morning glory.  It's very nice " even better than pak choi.  Is it the same morning glory we grow as decoration " the blue trumpet shaped flowers that look like bindweed's more interesting younger sister?  It's called ipomoea officially.  Can I eat it?

 I think the Chinese veg you mentioned maybe be Water Spinach (Ipomoea aquatica) & that is perfectly safe to eat. There is a lot of info in the following link.

http://en.wikipedia.org/wiki/Ipomoea_aquatica

I am pretty sure you should not eat the leaves of morning glory or the seeds as the latter are hallucinogenic.  

Yams & sweet potatoes belong to the same large family & their leaves are not eaten either.