I knew USDA kept a database of the nutritional value
of foods, but I didn't know what it was called. Their
incompetently designed website certainly did not direct
me toward this body of information -- arguably the most
important database they have. After much searching,
finally Google gave me the name of the database, and
with that the USDA search tool reluctantly coughed it up.

Here is a link to the main database web page:
http://warp.nal.usda.gov/fnic/foodco...SR16/sr16.html

And here is a link to page for searching the database:
http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl

From there, I finally found what I wanted, the nutritional
value of lotus root. It's almost identical to a potato,
in terms of water content, carbohydrate, and calories.
About triple the amount of fiber, but that's the only
good thing you can say about it. That, and the holes.