United Kingdom

I would be truly grateful if you could tell me what the name of this spectacular plant is. I bought it in Sri Lanka when the globose stem was the size of a table-tennis ball, and now, five years later, the stem is about 21cm in diametre. The little roadside stall I bought it from said the plant was originally from Holland, which may or may not have been true.They said it grows to be 2 metres across in 20 years, which may be true;it doubles in size every year.
The plant is unbranced, I could say, although the leaves rise out of the centre,and create a central stem-like spike to support the innermost leaves, a bit like some globose palm trees. The leaves are very long, narrow and serrated.
The plant loves sunshine and doesn't need a lot of water.The stem itself is silvery grey,and the leaves are pale green and about 2cm at the base, over half a meter long and mildly serrated.
Do you know what my plant is called?

• 27 Jan, 2011