There is an old bamboo grove (perhaps ~25 years) at the National Arboretum in Washington DC, at the bottom of the Asian Hill area, that is beginning to shoot. The biggest culms are almost 4" in diameter (my palm in the picture is a tad over 3.5" wide). I'm guessing it's P. vivax. What do you think?

It looks fuzzy like moso, but maybe the images are fuzzy.

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Lance Kleckner
http://www.bigfootwillow.com

In person, the culms did not appear to be fuzzy. That bottom picture is out of focus, but I included it to show the white powdery band around the node area, which is supposed to be typical of P. vivax after the sheaths fall off (some pictures I have seen of Moso have this too, though). The 4th picture from the top could be interpreted to have fuzz, I guess, but in person that looked more like the coloration of the culm than fuzz.
Some other reasons I was guessing vivax are:
the internodes on many look like the length of vivax (longer than moso);
the culm width seems about right for a mature grove (moso would likely be larger);
the shooting time seems about right (vivax supposedly is 'early-mid season'; this is May 6 in DC; moso would likely be earlier);
the shoots look like pictures I've seen of vivax shoots;
historical cold info: the grove of bamboo that merges into this one appears to have been planted in 83; if this was also planted in 83, the grove would have been young when a series of devastating winters hit (87-89, I think), that destroyed the Camellia collection there and spurred the Arboretum's development, under Ackerman, of cold-hardy varieties. Vivax is the most cold-hardy timber bamboo.

I should have gotten some good leaf pictures, as moso are small, while vivax are larger.

I vote for Viridis

I think the shoots would betray a Viridis ID due to the hairy little ears as it would also betray Vivax. I would not rule out the Moso.

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Brad Salmon, zone 5b/6 Southern Indiana
Winters -20 to -25C. Summers 30 to 35C , humid. 115 cm annual precipitation, frost free from May through early October. 259.3 meters elevation. Growing 150+ species. http://www.needmorebamboo.com/

Hey, you may have something there!

The bamboo next to this grove, that is growing into it, is yellow with green stripes. I was guessing that the tag there referred to it (the tag is next to a few yellow culms, but not far from the green ones). The tag says 'Phyllostachys sulphurea var. viridis'. I did a web search on it, not finding anything very informative. After your post, I looked in Meredith's 'Bamboo for Gardens' under P. viridis, and see a synonym listed as 'Phyllostachys sulphurea var. viridis'!


I wonder if this yellow bamboo is a separately-planted P. viridis 'Robert Young', or a spontaneous variant.





Getting wildly speculative, I see that Robert Young was a USDA bamboo expert, and this mixed grove appears to have been planted in 1983 at the National Arboretum. Any chance this is the grove where the cultivar 'Robert Young' first appeared?

I'm pretty certain that the shoots in your photo are not virids but it is entirely possible that some of the culms are. Some of your culms seem to have short Moso like internodes while others do not. The shoot looks very much Moso like and not like viridis at all.

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Brad Salmon, zone 5b/6 Southern Indiana
Winters -20 to -25C. Summers 30 to 35C , humid. 115 cm annual precipitation, frost free from May through early October. 259.3 meters elevation. Growing 150+ species. http://www.needmorebamboo.com/

It sure looks like a MOSO to me. The shoots are right and the close internodes in one of the pics looks right.

Michael McMillon

The thing is, many of the internodes are long for moso. So a question is, what kind of internode-length variability can there be for various species? While trying to ID this, I saw pictures of viridis & Robert Young where some culms had shorter internodes. Conversely, can moso have some culms with longer internodes (don't know, but I haven't seen pictures of it). If moso can't have long internodes like that, then the only way those culms could be moso was if there were multiple types of bamboo interplanted there.
Also, going back to my first guess, those new shoots look exactly like pictures of shoots of vivax. Does anyone see any details that would preclude them being vivax?

Yes, I believe there are pronounced auricles which vivax should not have. I like the theory of it being a Moso shoot that has perhaps had viridis/something else run into the same area.

My 2 inch Moso shoot is still 2 inches right at soil,level however those 5-6 nights of hard freezes that came just as the shoot poked out did not kill it but the growth was so slow that the internodes are extremely close together - 1.5 to 2 inches apart - for the first couple feet (tapering rapidly) and then as it quickly got hot again they grew with normal spacing. A later shoot that is a bit over 1.25 inches has produced a culm that will be as tall or taller than the fatter shoot due to the warmth when emerging, so weather can certainly shorten the internode length but I don't know that it will grow longer than is usual for the species due to heat.

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Brad Salmon, zone 5b/6 Southern Indiana
Winters -20 to -25C. Summers 30 to 35C , humid. 115 cm annual precipitation, frost free from May through early October. 259.3 meters elevation. Growing 150+ species. http://www.needmorebamboo.com/

Phyllostachys viridis "Sulphurea" is the same as Phyllostachys viridis "Robert Young". It is an older name not used much if any in the USA anymore. It is very common for older "Sulphurea" groves to revert to plain green Phyllostachys viridis. Given enough time and no selective removal of the green culms, the grove will eventually revert as the older yellow culms die out and are replaced with green ones. To a lesser extent you will find some Phyllostachys viridis "Houzeau" mixing in as well. All the groves here start reverting in as little as 20 years, or at least all of them I have seen. "Robert Young" is not very stable if you look at it in this time frame.

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Steve Carter
Carter Bamboo
http://www.carterbamboo.com

cell (979)665-1897
Brazoria, Texas

Thanks, that makes sense. Doing some more web searches, I saw "'Phyllostachys sulphurea var. viridis' " more often used to refer to green P. viridis, but sometimes also to 'Robert Young'--looks like there was some confusion there. (Edit: and like you said, "Phyllostachys sulphurea" referring to 'Robert Young'.)
Given the position of the tag, it looks like culms closer to the original plant are still like 'Robert Young', while the rest of the culms have reverted.
So a remaining question is: could all of those culms be from the original 'Robert Young', or is there a different kind of bamboo mixed in?

Update on this old post: while I was at the Natl Arboretum recently, I went and looked at the bamboo again, and they have new markers in the ground! Even with the updated name: Phyllostachys edulis. If there's a 'Haubrich' cultivar, this is probably it, as it came from Richard Haubrich in CA, 1985.