Other people say that in Southeast Asia they were struggling against malaria, so they cultivated cinchona trees (Chinchona pubescens), used to concoct quinine. Cinchona trees grow more vigorously if interspersed among Indian rose chestnut trees.
也有人說，他們在南洋打仗為抵抗瘧疾，於是種植提煉奎寧的金雞納樹，而金雞納樹和鐵刀木種在一起可提高存活率。