The respawn of the gatherables on this island is quite long. Maybe somebody gathered everything just before you arrived on the island. Try to switch channels there if possible.

I just found the rose. I was expecting a trade skill type gather-able like a mushroom, but it was a visible rose on the ground that triggered an option of "Look" when I was near it like a mokoko seed does. I personally have found 3 spots where they spawn, and have collected 2 of them within a minute of one another.