Today I called the Dept of Herpetology at the Bronx Zoo. I was pleased to be able to reach a knowlegable person on a cold call to the general information line.
As it turns out, the two ornates I saw were not the first uros they had. Previously, they had been given someone's pet uro that was not exposed to proper uvb in it's early life. The two female ornates were acquired as cb hatchlings from a breeder they had worked with after the health of the former pet failed.
I specifically asked about the grasses in their enclosure. As it turns out they pull up clumps of mature native grasses from the zoo grounds, wash and dry them well to remove insecticides & pests, and place it in the uros enclosure. Because they are working with what is growing on the zoo grounds, she was not able to identify the grasses. They sometimes use realistic looking pvc grasses from www.autographfoliages.com
In case anyone is curious, they keep the uros on 2-3 inches of a blend of sands (mostly playsand, some natural black & red sands for color). They mostly feed them dark leafy greens & chopped veggies, they never offer bugs. She also told me the zoo's opinion on soaking/baths; specifically that they are not recommended unless the uro is dehydrated.
That's it for now, if I remember anything more I will post later.
--Benedita