There has been little research done on these huge, rhubarb-like plants. They are listed on some sites as toxic to animals and on other sites as safe, so we feel it best to be cautious and advise not to feed until further information is available.
N.B. Not to be confused with the vegetable Rhubarb (Rheum spp.) which is high in oxalic acid and glycosides and should never be fed to tortoises.