Siouan root constraints

[cstelfer at ucalgary.ca]

Hey out there,

   I was wondering if anybody has ever taken a look at the root
constraints on stops in any of the Siouan languages.  What I want to
know is: are there very many roots with two voiceless unaspirated
stops?  The nomenclature for this type of root might be something like
TVT(V).  It seems to me that a lot of roots have one aspirated and one
unaspirated stop.  Is this accurate?  Also, would it be fair to say
that ejectives are relatively rare in the Siouan languages that have
them?

Thanks,

Corey.

PS.  I use the word "root", but I think most Siouanists prefer "stem".  If
someone wants to clarify the difference between these two terms in their
Siouan usage I would appreciate it, but perhaps that's a question for
another day.