This is a big bamboo! It forms a stand of considerable spread on the SE corner of the Asian Collections at the bottom of China Valley. Some of the canes approach 5" in diameter. I have a more usual (smaller) form in my own garden; its first thrusts are not so interesting. Bamboo grows fast enough without the benefit of these 90+ degree days following a cool wet spring. I will check this particular culm tomorrow and see what progress it has made.
We have had three consecutive days with the high temperature in the mid 90sF. These are following a cool spring with more than adequate moisture. Plants have exploded. My Northern Red Oak has gone from flowers only (no doubt dispatching quantities of pollen) to 5" leaves in 3 days. Views have closed up all around as the forest trees hastily refoliate. If you stand still outside you will be coated in the greenish golden powder of pollen; Leaving the Arboretum this evening, the cars in the parking lot were all heavily pollinated.
I sneeze as I write this post. For much of my life I was unaffected by pollen. I suspect that continual exposure produces hypersensitization; or I'm just weakening as I age! I think the former.