Definition
Botanically, Mitragyna speciosa is a long-lived tropical tree with continuous vegetation, that is, without a pronounced period of dormancy. In the natural environment of Southeast Asia the tree grows, flowers and produces fruit practically all year round, with the intensity of the individual phases changing according to the rainy season.
Germination and growth
The seeds of M. speciosa are tiny (about 1 mm), with a short viability - on the order of days to weeks after collection. For this reason, in practice they are often propagated by cuttings or vegetatively. Germination occurs at temperatures of 25-30 °C in a peat-sand substrate at high air humidity.
Under ideal conditions a young tree grows 60-150 cm per year. After 2-3 years it reaches a height of 3-4 m and begins to form leaf mass suitable for experimental harvesting. The tree reaches full productivity (stable leaf weight, developed crown) between its 5th and 7th year.
The growing season in the tropics
The tree does not have the pronounced dormant state known in temperate-zone plants. The leaves fall gradually once they reach an age of 6-9 months and are replaced by new ones. This means that a single tree bears leaves at different stages of maturity at the same time - an important factor during harvesting.
In the rainy season (typically November-March in the Indonesian part of the range) the tree is in intensive growth, and in the drier season it slows down slightly. Leaf harvesting is adapted to this dynamic.
Inflorescence
The inflorescence of M. speciosa forms spherical yellow to yellow-green heads 2-4 cm in diameter. This structure - dozens of small five-part flowers assembled into a conical head - is typical of the genus Mitragyna and helps with botanical identification, especially in distinguishing it from related genera.
The inflorescence is pollinated by insects (mostly small hymenopterans). The fruit is a minute capsule with many seeds dispersed by the wind. In plantation conditions, seed collection is seasonally coordinated with the care of the mother trees.
Ageing and length of productivity
A fully mature tree reaches a height of 10-16 m, exceptionally up to 25 m. The tree's lifespan in the natural environment exceeds 50 years; in plantation conditions it is usually 30-40 years, after which it is replaced with a new seedling because of the declining leaf quality and more difficult harvest.
As the tree ages, the ratio of alkaloids changes - older trees tend to have a more stable content of mitragynine, but the total amount of leaf mass grows more slowly than in younger trees.
Frequently asked questions
For how many years does the tree yield leaf usable for drying?
From the 2nd-3rd year to the 30th-40th year, and longer in the natural environment. It reaches full productivity between the 5th and 7th year.
Does kratom flower in Europe?
Not in open ground. In the greenhouses of botanical gardens, exceptionally yes, but fruit is generally not obtained because of the absence of natural pollinators.
How does a young tree differ from a mature one?
A young tree has a relatively higher proportion of paynantheine and a lower proportion of mitragynine. The leaf venation is less pronounced and the leaf is thinner.
What is the difference between Mitragyna speciosa and Mitragyna parvifolia?
Both species belong to the same genus but differ in range (parvifolia in India) and in alkaloid profile - M. parvifolia does not contain mitragynine in a commercially relevant amount.
References
- Sukrong S. et al. (2007). Molecular analysis of the genus Mitragyna. Biological & Pharmaceutical Bulletin, 30(7), 1284-1288.
- Raffa R. B. (Ed.) (2014). Kratom and Other Mitragynines. CRC Press.
- Brown P. N. et al. (2017). A botanical, phytochemical and ethnomedicinal review of the genus Mitragyna. Journal of Ethnopharmacology, 202, 302-325.
