An exception to this rule are members of the Chenopodiacea family which includes beet greens, spinach and chard. The oxalic aid content of these greens bind calcium into an insoluble compound that is of little use to the tortoise. Parsley and Mustard Greens also contain an unacceptable amount of oxalic acid and should only be fed sparingly. There has also been some indication that members of the Brassica family which includes cabbage, collards, kale and broccoli can cause goiter if fed in excess amounts, but the feeding of a varied diet that is not heavily based on these plants should offset this tendency. If in doubt about this a small amount of dried or powdered kelp can be added to offset this tendency.
Many keepers make use of Brassicas with no ill effect.
Basing a diet on this green is a long slow death sentence. As can be seen in the table it at best can be considered an empty food. It is low in fiber and has a bad Calcium to Phosphorous ratio as well. It must be remembered that in addition to any dietary program that regular supplementation with a calcium based supplement with vitamin D3 is strongly advised. I have highlighted the foods that incorporate the above criteria, that being the combination of high fiber, low protein, a high Calcium to Phosphorus ratio and a lack of high oxalic acid content.