Seems like there were a lot of new nothogenus names this year at the orchid show (so far: Brassostele, Papilionanda, Neostylis, and Sarcochilus), and now we have a new one. In most (all?) of those cases, the plant wasn't that different from what we've seen before, just a familiar genus with a new, less-recognizable name, and that's also what's going on here: Oncidium onustum got changed to Zelenkoa onusta, so Oncidium Kukoo becomes Zelenkoridium Kukoo.
I found it interesting that O. onustum was the only Oncidium species to be moved to Zelenkoa, and Z. onusta is the only species in Zelenkoa; it didn't look that different from the Oncidiums. So I went looking for an explanation.
And it turns out to be more different than it looks. And also less different than it looks. I will explain.
According to Wikipedia and this video, Zelenkoa onusta grows:
• epiphytically, which is a perfectly orchidy thing to do,
• at high altitude, which doesn't seem weird either,
• in direct sun, which is a little unusual for the kinds of orchids that get widely cultivated, but sure, why not,
• on top of desert cacti (tilted head, puzzled look),
• and during the dry season it pushes its roots into the cacti it's growing on and sucks moisture out of them, so it's parasitic, which is so out of character for orchids that when I searched for "parasitic orchids," I got lots of results along the lines of, "Are orchids parasites? Absolutely not!"1
Except that when I looked for more specific information about Zelenkoa's parasitism, I found a lot of botanically-oriented, big-word-type sites that didn't mention it at all. For example. Which you would think that parasitizing other plants would be unusual enough that it'd be the main piece of information people would bring up, whenever talking about the orchid.
Also Z. onusta certainly doesn't have to be parasitic, because it can grow and live out a full life cycle on all sorts of surfaces, including rocks. Which makes me wonder where the parasitic claim is coming from, originally.
And it turns out that the parasitism wasn't even the reason it was separated from Oncidium in the first place; it lacks a particular minor-sounding structure in the flowers that the other Oncidiums all have, or something boring like that.2
The hybrid, Zelenkoridium Kukoo, has a similar appearance,3 but is apparently much easier to grow. Though the US Botanic Garden in Washington DC helpfully informs us that Z. onustum [sic] is "one of the easiest orchids to grow once you understand its native habitat,"4 it sounds pretty challenging from everything I've read about it. So my advice is, stick with Kukoo, if you want to grow something that looks like this.
Zelenkoridium Kukoo = Zelenkoa onusta x Oncidium cheirophorum (Ref.)
There are apparently a lot of people whose high school biology teachers never told them about epiphytes. So these people see orchids growing on the trunk of a tree, or on the branches of a tree, and assume that it must be a parasite, because why else would a plant grow on another plant? The "absolutely not!" answers are directed at these people, and is essentially correct for most practical purposes.
Except that then there are also some orchids that have turned symbiotic relationships with fungi into parasitic relationships, where the orchid only takes from the fungus. (But don't feel too bad for the fungus, since it's parasitizing a different plant: the fungus is apparently also living in the orchid's roots, like a symbiotic fungus would, so I don't follow how it's managing to take nutrients from a different plant, but I am assured that this is what's happening.) Corallorhiza maculata and Danhatchia australis are a couple orchid species that make their living this way. When people think of parasitic plants, they usually mean plants that steal from other plants, not fungi, but it's still parasitism if the orchid's not giving anything back to the fungus. So the answer at this level to "are orchids parasites?" is, a few of them, yes. Technically.
And then there's Z. onusta, which if we believe the video -- and we possibly shouldn't -- actually is a parasite of other plants in the straightforward way that a layperson would imagine, in which case the answer is, yes, at least one of them, but not the one you're asking the question about.
2 I mean, it's not boring if you're a taxonomist or an orchid specialist, I suppose. But that's why we restrict plant taxonomists to renaming things endlessly, and don't let them run TV networks: because they have weird ideas about what's interesting. ("Next on Lifetime: Mother, May I Cross-Pollinate Without a Tabula Infrastigmatica?")
3 Z. onusta has broader, more square-shaped blooms, but that's the only obvious difference I can see.
4 This resembles "easy to grow provided that you can supply the exact conditions it wants to be grown in," which is tautological, except that the USBG version isn't even true: understanding its native habitat does sweet fuck-all for you if you can't reproduce it. (What happened to you, US Botanic Garden? You used to be cool.)