The alkaloidal pattern in the leaves, stem-bark and root-bark of Mitragyna parvifolia (Roxb.) Korth. collected from mature trees growing in Ceylon has already been discussed (Shellard and Houghton,1971). The acquisition of seeds from the Singhalese trees and their ready germination in the greenhouses of the Pharmacognosy Research Laboratories at Chelsea College, made it possible, not only to investigate the alkaloidal content of the seeds but also the distribution of alkaloids in all parts of the young plants. The results reveal an interesting distribution of alkaloids, which together with the knowledge regarding the pattern of alkaloids in the mature tree can lead to an interesting discussion regarding their formation, relationship, movement and possible function in the plant. In addition two alkaloids not previously obtained from Mitragyna species, were isolated and characterised. Both were Δ¹⁸ open E ring alkaloids, one being an indole and the other an oxindole alkaloid. The former is Δ¹⁸ hirsutine (designated hirsuteine) and the other is corynoxeine (Δ¹⁸-rhynchophylline) previously reported in Pseudocinchona africana A. Chev., by Nguyen An Cu, Coutarel and Janot (1957) and also obtained synthetically from corynantheine by Finch and Taylor (1962).