I bought this bamboo from Tropical Bamboo in January 2020, and planted it in the backyard in February 2020.  It's supposed to be Bambusa Guangxiensis, aka "Chinese Dwarf."  The official description in Kew and eFlora and other places basically ranges from 3-5m (10-16') and up to 30cm (1.25") diameter.  Clearly that is not what I planted.  The tallest culm in the below photo is 35 feet and just over 3 inches in diameter, and it wasn't completely finished growing. 

Any thoughts on what species it is?  I was thinking Dendrocalamus Brandisii due to the furry brownish lower culms, but it was completely defoliated at 24-26F with frost, and the leaves are kind of moderate-sized.  Dendrocalamus Hamiltonii (not the red shoot type) is another possibility, but the leaves are much smaller than expected.  One probably important distinguishing feature is that the blades on the new shoot sheaths are all in the same plane.  You can sort of see this in the photo of the new shoot in the wheelbarrow below.  I think that rules out species like Oldhamii, which are arranged at random angles around the new shoot.  They are also very dark, though it's hard to see that in the pictures.

And the tops of the culms, cut at about 3' tall

Middle culms are medium green, you can see one new culm with the white/tan furriness in the wheelbarrow:

And a new shoot cut up in the wheelbarrow, with dark new blades arranged at 180 degrees to each other:

I'll try to get a couple of better lower culm photos tomorrow.

Here's a better photo of the lower culms, I even found the original Tropical Bamboo tag!

So I decided to send the photos to Tropical Bamboo, and Sam Hudon replied back with a positive ID for Bambusa Guangxiensis.  He said that most people top them at 6-8' as a hedge, and they end up growing a large number of <1" diameter canes.  But if you let it grow to it's natural maximum then it does grow big.  He didn't have an estimate on the maximum "untrimmed" size.

Sam is actually Samantha Hudon.
Tropical Bamboo has been known to mislabel plants.

9 hours ago, John Dodge said:

Sam is actually Samantha Hudon.
Tropical Bamboo has been known to mislabel plants.

Welcome to PalmTalk!  At the time I had only an email communication with her, and just assumed "Sam" was a guy. 

In this case it was the right species, it's just that apparently everyone cuts the tops on Guangxiensis to make a hedge.  It's super bushy when small, so a 6-10' hedge is probably amazing.  My problem is that access in that spot in my yard isn't easy for a ladder, and it's not particularly frost hardy.  With yearly frosts in the ~28F range it wasn't going to be a good sound or sight block for the neighbor's 2nd story windows.  They house is totally obscured in the first photo, but not from December thru March!