Well, I don't believe many of those are correct...
Sunberries, for starters, are supposed to have a little "liquid sunshine" inside of them. Like the feather trees and bubble grass, they're not really supposed to make sense and are quite magical. They're berries with a little literal sunshine inside them that can be fermented.
I don't know why you'd think bloated tubers are a type of grass, when they almost certainly refer to more simple potatoes. Longland grass is just any generic wild breed of wheat, at that. Toady didn't take the time to make very specific types of plants, they're just generic potatoes and wheat.
I would expect rope reed to be more like papyrus (and maybe blended in function with flax), which is a reed itself. However, as I said, it has those lines that probably mean it physically appears similar to rope.
Kobold bulb exists for purely magical/alchemical purposes, and as such, relating it to an onion seems a little strange - it could be almost anything that produces a liquid, and it's a magic liquid at that.
For the underground plants, he pretty clearly was going for more fanciful things, and didn't particularly care for realism. He has cave wheat that is apparently just literal wheat that grows in caves.
He also lists in the raws plump helmets as "MUSHROOM_HELMET_PLUMP", and "MUSHROOM_CUP_DIMPLE", but then, "GRASS_WHEAT_CAVE" and "GRASS_TAIL_PIG". Pig tail is a type of grass, like wheat is (cave or otherwise). It's also a curly type of grass, apparently curled like a pig's tail.
Incidentally, quarry bushes (listed as "BUSH_QUARRY", not "MUSHROOM_BUSH_QUARRY") have [PREFSTRING:gray leaves]. Not "musrooms that look like leaves", but "leaves".
Again, every indication is that it's a literal bush that looks gray and has rock-like nuts and grows underground.
And that's why you shouldn't use Bing - it's seriously made to return the results that gave Microsoft the most money, so you're always going to have things that give you the information you want, like Wikipedia articles on the topic you searched for, below results that sell you something unrelated.