Cyathea robusta is a large, very beautiful species from Lord Howe Island.  It has very attractive, thick, erect fronds and light brown scales on the croziers, not unlike C. brownii.  As the stipes mature the scales fall leaving the thick, light green stipe visible.  The fist-sized croziers of this species are spectacular when uncurling in the spring.  A good performer in cultivation, it has been known to withstand frost and snow in Victoria (although cold-tender when small), and is probably a tad hardier than C. cooperi (guessing 25°F).  It does not resist hot temperatures well when young either.