I don't have any pics...but the larger form is 'daikokuchiku' and turns black faster. It starts to turn black immediately and takes about a year to totally turn black. The regular variety takes about two years to turn black. There is a link to a photo I took in the thread below:
Here's a link to a photo that I provided to a website (I didn't get the photo credit, but it is a photo that I took of my black bamboo).
Phyllostachys nigra"Black Bamboo" | Tejas Tropicals
This photo is of the larger variety ('daikokuchiku') but this guy is selling the regular form so it doesn't mention the variety. The guy I bought the 'daikokuchiku' from has it listed as growing to 50' with a 3" diameter and taking down to 0F. Size does depend on zone and might not get that big in zone 6, but the mother grove is in zone 7 and is pretty impressive. I really think his culms are actually closer to 4".