Among his many discoveries was the medicinal plant Kratom ( Mitragyna speciosa ) .
Korthals was the official botanist with the Dutch East India Service from 1831 to 1836 .
Among Korthals ' many discoveries was the medicinal plant Kratom ( Mitragyna speciosa ) .
Korthals was the official botanist with the Dutch East India Service from 1831 to 1836 .