There are four Rauwolfia species reported as native to the Philippines viz. Rauwolfia amsoniaefolia A. DC., R. samarensis Merr, R. membranacea Merr., and R. loheri.
Sibakong is a shrub or small tree with milky juice which reaches a height of about 15 meters but usually smaller. Leaves are ornamental, occurring in whorls, lanceolate, 6 to 12 centimeters in length, 1.5 to 3 centimeters in width, rather narrow and sharply pointed at both ends. Flowers are small, white, fragrant and borne on compound inflorescences. Fruit is somewhat rounded, about 8 millimeters in diameter, and obscurely two-lobed.
- In thickets and secondary forests at low and medium altitudes in Cagayan, Ilocos Norte, Isabela, Pangasinan, Nueva Ecija, Batangas, Camarines Provinces in Luzon; also in Mindoro, Lubang, Masbate, and Mindanao.
- Also occurs in Timor Laut, Kei, and the Tenimber Islands.
- Study yielded a creamish, amorphous alkaloid, amsoniaefoline. (Gomez, Da Silva and Garcis)
- Study on alkaloid content of different parts of the plant showed: stem bark 2.06%. whole root 2.44%, wood of root 1.39%, bark of root 4.16%, leaves 0.96%. (2)
- New buds used for stomach disorders of young babies.
• Isolation of reserpine and rescinnamine from Rauwolfia amsoniaefolia A. DC: -- Preliminary analysis of crude drug yielded alkaloids: reserpine, rescinnamine, deserpidine, aricin, yohimbine, methyl reserpate, possibly ajmalicine, and an unidentified alkaloid from the stem bark. Roots yielded the same alkaloids except deserpidine. (2)