I've been trying to grow Scoliopus bigelovii for years...

I once heard someone who was growing it say that it needed
to be kept absolutely dry during summer. My experience doing this
has resulted in plants that although they have survived have not
advanced at all. When I dumped the soil out to see if there was
anything there I could barely make out some thin roots.

Ian Young ... advised year round water and a very deep pot for the
extensive root structure. This makes sense to me since most of the
ones I've seen in the wild are close to water and could go down very
far to get to the water table during their summer dormancy.
Certainly the root structure that others have described did not
match my plants that may have been desiccated in their dry soil
without water for many months.