I guess I should have saved those nasty roots

I believe it was a soaptree yucca. It actually looked like some kind of ugly-ass hybrid between a soaptree and a banana yucca, but the roots were all wet and sticky and milky inside. I think that makes it a soaptree. Just in case anyone was interested.

http://helios.bto.ed.ac.uk/bto/desertecology/yuccas.htm