a rainforest megaherb; leaf blades to about 60 cm long

I've tried growing these in my fernery at home; they survive but only just and with lots of water, and are a pale comparison with this healthy specimen.

In response to Gill's query, botanists use the term "herb" to mean "non-woody plant" without implication of edibility. In this case, quite the opposite is true (from Australian Tropical Rainforest Plants):
"This species is dangerous, the tissues contain sharp needles of oxalate and if chewed cause painful irritation, burning and swelling of the lips and tongue. Fatal cases of poisoning have been reported in children. Everist (1974)."