I believe that Shikakai is a saponid just like Aritha powder is, and Aritha definitely creates suds. I did a search on Shikakai, and it is a natural cleanser. I believe it's supposed to suds, but I could be wrong.
http://en.wikipedia.org/wiki/Shikakai
Thanks Muffin! That would explain it. It also said this: Usually no rinse or conditioner is used since shikakai also acts as a detangler.
From what I have read about other people's experiences this stuff actually causes tangles. My hair didn't feel tangled after using this poo but it certainly wasn't detangled enough to go without conditioner.