The vein
What the red actually is
Turn the leaf over. Down the centre runs the midrib, and out of it the side veins arc away in even pairs to the edge. On this leaf all of that is a clear red-brown, and it carries on down the stalk into the stem. That is the red. It is a feature of the leaf you can point at, and it is the only thing the word describes.
In the trade the colour is taken as a rough record of when in its growth the leaf was picked and what happened to it between the tree and the mill — the same leaf handled two ways does not come out the same. The green sits between this and the white, whose midrib stays pale cream-green.
The colour is the smaller half of the story, though. Kratom is a heavily marketed plant, the strain names most of all: batches do differ, but ninety-nine times in a hundred the difference is in where the leaf grew, which subspecies it is, how it was grown and how it was dried.
So we stopped selling names. We used to carry Green Borneo, White Maeng Da, Bali Gold, Red Borneo, Red Vein Horn, Yellow Maeng Da, Green Maeng Da and Green Vein Kapuas. Now there is one farm and three veins — this red, a green and a white.