With yellow culms, wouldn't this be a cultivar - such as 'Robert Young' - rather than the species (unless it's an unselected seedling variant)?
In general, I love a good mystery, but bamboo nomenclature is pretty frustrating. Ron is correct. Having the benefit of seeing the plant in the flesh, I can safely say it is 'Robert Young'. In fact, we received it under the name Phyllostachys viridis 'Robert Young' in 1998 from a local bamboo retailer. Now, I'm just speculating, but I think our accessions technician at the time was using the RHS Plant Finder to verify names (not a bad habit, all things considered) and read that Phyllostachys viridis is a synonym of P. sulphurea var. viridis. Further, seeing that P. sulphurea var. viridis is distinct from P. sulphurea 'Robert Young' led her to conclude that the retailer was in error. Indeed, the retailer had assigned the wrong name (and still does in the catalogue), but the cultivar name was the correct one. Record keeping in a botanical garden (or any garden) is a challenge and we rely on a few key references to keep us honest. The (most up-to-date) Plant Finder is one. For bamboo, we use D. Ohrnberger's The Bamboos of the World (Elsevier, 1999), which is the most complete and extensively annotated text we've found. This helps us keep the synonymy straight. For example, the correspondent CJ Whyte suggests the plant pictured could be Phyllostachys viridis 'Sulphurea'. Not a bad guess, but the correct name for that plant is (evidently) P. sulphurea f. sulphurea. However, beyond the reliability of references, we also have to go out in the garden and verify the plants are what we say they are. Unfortunately, the process of revisiting accessions to ascertain their nomenclatural and botanical accuracy is slow and frought with difficulty. We have a lot of territory to cover here (ca. 9,000 taxa over 25 hectares), with a small curatorial staff (4--only one is a trained botanist). Our inventories have improved considerably since the late nineties, in part because of our access to Internet resources, such as the Flora of China Online, but we still have to spend an inordinate amount of time on certain plant groups. The "worst" plants are those that are either new to cultivation (not enough information) or those that are horticulturally valuable (too much information). Bamboos are in the latter category, being both collectable and infinitely variable. Commercial enterprises are notorious for not keeping up with changes in nomenclature, particularly if it doesn't affect the bottom line (it serves us right for shopping retail, I suppose). To be fair, we can't really blame people who don't have access to the resources and kind of expertise we can marshall at a university. Unfortunately, there is no one here at UBC who I would call a bamboo expert. Some of us know a thing or two, but every once in a while a plant is accessioned with the wrong name. We would like to get around to reviewing everything on a regular basis, but that just isn't possible--at least with the frequency that we'd like. If we make a mistake, the blame is mine and I accept it. I welcome the advice and opinions of others to help me do my job. Keep it coming and thank you.
I still find RHS resources to be far from adequate regarding nomenclature, so a word to the wise on relying on them too much. And why does online FLORA OF CHINA have Betula albosinensis (or maybe just B. a. septentrionalis--I haven't looked at it in awhile) placed in synonomy under B. utilis, without explanation?
The RHS is unapologetically horticultural in nature. Its publication, The RHS Plant Finder, is one of the best resources for up-to-date nomenclature because it is constantly reviewed and updated. It isn't perfect, and it certainly isn't particularly useful for obscure North American cultivars or infra-specific taxa that aren't well known outside of botanical circles. Nevertheless, as a scientific resource, it is generally pretty good, but as mentioned before, the specialist literature must also be consulted.
I have actually met the Lady responsible for the plant finder (very nice she is too) i cant imagine a more difficult job, its just taken me 4 months to write my catalogue only 800 entries to check, imagine 75,000 plants to check.
North American cultivars don't have to be obscure for them to get them wrong over there. That's not limited to The Plant Finder. Later: I just checked a couple names they used to have wrong, one is now listed as an Accepted Name. The cross referencing of the other to another name may be recognition that the plant they have over there as the first is probably actually the second; it's impossible to tell if they are wrongly saying the two are the same cultivar. So, they may be getting closer. Last time I looked up a bunch of names there were quite a few mistakes.
Not to drag this out too much longer, but in my experience, mistakes brought to the attention of the editors of The RHS Plant Finder are quickly acknowledged and addressed.
