Definition
In commercial practice, kratom powder is designated by the colour of the central leaf vein - white, green or red. This designation does not represent botanically distinct varieties but primarily the growth phase of the leaf at the moment of harvest and the subsequent method of drying or fermentation. The vein itself is a pronounced longitudinal vascular-bundle structure running through the centre of the leaf blade.
What the leaf vein is and why the type is distinguished by it
The central vein (costa) is the main vascular bundle of the leaf, providing the transport of water and assimilates. In Mitragyna speciosa it has pronounced pigmentation that changes during the development of the leaf. The pigments responsible for the colour are:
- chlorophylls (dominant in the mature green leaf),
- anthocyanins (red and purple pigments, dominant in ageing and mature leaves),
- carotenoids (yellow, prevailing in young and ageing leaves when chlorophyll disappears).
In commercial terminology the vein colour is a guide for estimating the maturity of the leaf and the processing conditions - no formal botanical division of varieties by colour exists.
How white, green and red arise
"White vein"
Denotes leaves harvested in the early vegetative phase, when the vein is still pale (carotenoids prevail over chlorophyll). This raw material is usually dried without pronounced fermentation, in a shaded space with a minimum of UV radiation.
"Green vein"
Leaves harvested at the phase of full maturity, when the chlorophyll content is at its maximum. Standard drying in partial shade, with a relatively short exposure time - which is why the raw material retains a dark green hue.
"Red vein"
Leaves harvested in the late phase of maturity, when the anthocyanin content in the veins increases. The raw material is typically subjected to longer sun-drying or partial fermentation, during which oxidation of both pigments and alkaloids occurs.
What changes chemically in the process
Chemically, the vein colour and the processing method manifest as a shift in the ratio of the main alkaloids:
- "White" and "green" leaves tend to have a higher relative content of mitragynine;
- "Red" leaves (especially fermented ones) tend to have a higher proportion of 7-hydroxymitragynine, which is formed by the oxidation of mitragynine.
This shift, however, is on the order of a few percentage points and highly variable between batches. A reliable profile is provided only by HPLC analysis of a specific sample.
Myths and marketing
In commercial communication, the "colours" are often presented as clearly distinct products with a predictable profile. Scientific data do not confirm this picture:
- the mitragynine/7-OH-MG ratio fluctuates between batches of the same "colour" designation;
- the designation "yellow" or "gold" kratom is purely a marketing term with no botanical background;
- the vein colour cannot be reliably determined from the powder - it is set by the producer according to the original leaf.
From an analytical standpoint, a batch's specific COA has greater evidential value than its commercial designation.
Frequently asked questions
Is "red/green/white" a botanical term?
No. It is a commercial division by the growth phase of the leaf and the processing method. Botanically it is a single plant - Mitragyna speciosa.
Does a yellow or gold vein exist?
A yellow or gold vein does not exist in nature. These names denote blends or processing (fermentation of green raw material) and have no botanical basis.
Can the vein colour be determined from the powder?
Not reliably. After grinding, the leaf loses its visual distinguishing features. The colour of the powder is affected by a number of factors (oxidation, grinding, moisture), not just the type of original raw material.
Do the colours differ fundamentally in chemistry?
They differ in the relative ratio of alkaloids, but the differences are a few percentage points. Variability between batches of the same designation tends to be greater than between the "colours" in general.
References
- Singh D. et al. (2016). Traditional and non-traditional uses of Mitragyna speciosa. Journal of Ethnopharmacology, 192, 24-34.
- Sengnon N. et al. (2021). Phytochemical comparison among different colour-vein cultivars of Mitragyna speciosa. Molecules, 26(17), 5141.
- Brown P. N. et al. (2017). A botanical, phytochemical and ethnomedicinal review of the genus Mitragyna. Journal of Ethnopharmacology, 202, 302-325.
