Most really weedy Ipomoea grow just fine from tip cuttings taken during warm weather - same as sweet potatoes (I. batatas.) Many can even be rooted in water. Yes, they do form tubers from cuttings. I haven't tried this with I. p. but the plant is so easy to grow and vigorous I bet it would work. Remember, they are just tuberous morning glories. As with growing sweet potatoes for food production, give enormous amounts of root space, water, and fertilizer if you want lots of tubers. Then in future years you can raise the tuber farther and farther out of the soil each spring when you repot the plant. They are highly susceptible to spider mites in times of low humidity. Spray the vines with water frequently during the growing season. They can be overwintered completely dry, above freezing, on a shelf or even in the dark of a closet or basement. Succulent vendors tend to carry succulent morning glories. Arid Lands and Out of Africa, both in the USA, often have them. Another place to ask questions about cacti and other succulents is the cacti_etc mailing list, which has something over 2,000 members worldwide when last I heard. Leo Martin Phoenix Arizona USA