Malay Magic by Walter William Skeat

4. The leaves of the gandarusa (Insticia gandarusa, L., Acanthaceæ),

a plant described as "often cultivated and half-wild--a shrub used in medicine." The selection of this plant is said to be due to its reputation for scaring demons (`alamat menghalaukan hantu). So great is its efficacy supposed to be, that people who have to go out when rain is falling and the sun shining simultaneously--a most dangerous time to be abroad, in Malay estimation,--put a sprig of the gandarusa in their belts.