I've got a clump of bamboo in the garden; it's got lovely dark almost black stems. I took the secateurs to it to get a sample for sketching.
I don't know why I cut it off at the bottom..... I ended up with about 4 ft of stem! I propped it against the coffee table to draw the joints, and annoyed DH who was trying to watch the TV and didn't appreciate the addition of a small jungle.
Below: a few pencil sketches for reference on leaf shape and the growth joints on the stems.