Between the clear, beautiful art, filled-in template, highly detailed description, distinct and bounded niche, and minimal errors throughout, this is one of the best genus group submissions I have ever seen. I would recommend this as a shining example to aspire to for anyone developing a genus group.
Because this would have a big effect on ecology in several habitats, I recommend going into more detail on which species and genus groups it makes extinct, uncommon, or limited before approval, so it doesn't have to be guessed and implemented later.
Possible Size Problems
While the minimum size is 25 cm, which is half the size of a Dome Crystal, the size is measured across, not in height. The rules don’t say anything about whether this is acceptable. Admittedly, it does have a very distinctive niche, so the Low Competition rule might apply if changing measurements from height to width is an issue.
Ecology
I wonder how these interact with Oozes. I’m not sure if they’re adapted to grow over carnivorous oozes, and Oozes colonies can be very large. Oozes might be able to slow their spread, though to what extent is hard to say, because Oozes’ description is so sparse.
Since these have a big effect on ecology, at least in a few specific habitats, it’s worth specifying which habitats have “platelands” that make it hard for small purpleflora and blackflora to survive. It’s also worth mentioning if it makes any species extinct, or at least uncommon. The present ecosystem has an uncommon/rare specification for a few species if they live in multiple habitats and are significantly less common in some than others.
As one example of a genus group likely made less common because of it, Pioneeroots are limited to actual soil to grow in, so if they can’t access soil in the platelands, they’re likely rare.
Notably, Tepoflora are only a few millimeters tall, so Plateland Crystals would easily cover them. Yet, a few species are purely detritivores, so that wouldn’t kill them. If these make photosynthetic Tepoflora extinct in certain habitats, it might be worth mentioning: (Largely nonphotosynethetic varieties in [habitat] and [habitat], due to Plateland Crystals influence”) for the Koseman and Wallace genus lists.
Description & Template
A quick check suggests “lenticels” applies to trees, not lichens (the closest equivalent), but Sagan 4 has used terminology in unconventional ways before, so this is fine. This suggests its ancestor also used lenticels, although I suppose that’s the most straightforward option available. Perhaps this might cause problems for a few crystal flora species, but it seems sensible for most of them, at least.
Minor Oddity: There’s an unusually large amount of space between the template and description. Some of the paragraph breaks also have excess space. This is trivial and can be corrected on the wiki, though: I’m noting it only for thoroughness.
“competition free” Ideally, “competition-free”.
“Crystals. shells” Capitalization error.
“shuttles the balls into crooks” Cracks?
“overtop of the” On top of.
“the marbleflora budding making up for lost members of their flock.” Do the buds grow to occupy air spaces? Do they push on and expand air spaces? Are they replaced by budding marbleflora which haven’t been encased yet?
“nitrogen hungry” Ideally, “nitrogen-hungry”.
“colonize throughout spaces”: “colonize spaces”.
“offcenter” Off-center.
“Organism, the face”: “organism, and the face”.
“top of one another the crystals” There should be a comma after “another”.
“Once accessing groundwater” Once it accesses groundwater.
“The generation before”: “and the generation before”.