Black Bamboo identification please

[Louise2014]

I have a black bamboo clump growing in my garden in Harare, Zimbabwe. It is not like ones you have on your site in that the trunk is not circular on the transvers cut. Rather, it is elliptical.
Otherwise it grows very like a grassy clump with long leaves and the shaft is covered in a downy, white powdery bloom which, when polished off, reveals a beautiful aubergine purple underneath.
It does not grow to more the 5-6cm diameter.
I wish to export this bamboo to Ireland for the World Flower Show but I need its botanical names.
Can anyone help?

[moriphen]

Sounds like a tropical grass, are the leaves directly attached to the stems? If you do not see branches supporting individual leaves its not in the bamboo family. As for the elliptical shaped culms/trunk that is something I have never seen in any bamboo.

[Louise2014]

Thank you for that answer. So far as I can see the leaves are directly attached to the stem. Each section does however have a nodule, but what will grow out of it I am not sure. I will check on an older stem. Is there any way I can post pictures on this forum? I have them in jpeg format.
If it is a grass, any suggestions where I may be able to identify this plant? Thanks for your input

[dependable]

There is a place to upload attachments in box below this one you type in.