Phyllostachys Parvifolia - This bamboo is extremely rare in the US and I went to great lengths to obtain mine. In Europe it is reported as being extremely hardy and able to reach impressive sizes in cold climates. Like the revered Phyllostachys Edulis, Parvifolia has very elegant, tiny leaves on massive culms creating a beautiful form. To my eyes this bamboo appears to be very much like Phyllostachys atrovaginata, with slightly different coloration on the culm leaves of new shoots and perhaps the foliage leaves are slightly smaller.
   Based on what is reported in Europe, I expect/hope that this bamboo will exceed 30 feet by 3 inch diameter in Zone 6 but it may be years before there are many plants available here as this bamboo has a reputation for being tough to propagate. Due to it's rarity, mine spent it's first winter in a heated space which it did not seem to like. It held up well in the cold snap of 2/2007 but the deer heavily browsed it so I could not tell for certain how well the leaves held up - all branches leafed back out, some that were not eaten sustain only minor leaf burn.

UPDATE 2010: A couple more winters of experience, this bamboo as a 4 year old sustained heavy leaf burn and minor culm damage at -8F with strong winds. Mine is sited in a fairly wind protected area. I now have started 2 additional groves from this original plant and have sited them in sunnier spots. This bamboo seems to be able to produce new culms about the same size or slightly larger in the first spring after being divided, then the following year it seems to leap up to the 1 inch+ diameter mark. The older grove also quickly sized up but once above an inch it seems a bit slower to get bigger but is now current 1.5 inches+ on the new culms.