Take "Paraiso" (Melia azedarac Linn.), or commonly known as Bead tree or China Berry. Its fruit is so toxic that eating it will result in paralysis, unconsciousness and difficulty in breathing that could lead to death. Parts of the plant that also have toxic substances are its flowers leaves and bark.
In the publication "Useful Plant with Toxic Substances" of the Ecosystems Research and Development Bureau of the Department of Environment and Natural Resources (DENR), "paraiso" and 11 other forest trees were identified to have toxic substances and can pose risk to human health due to improper handling or plain ignorance about the potential danger they pose despite their beneficial uses.
The other species include the Molave tree (Vites oarviflora Juss), Atis (Anona squamosa Linn.), Adelfa (Nerium indicum Mill.), Baraibai tree (Cerbera manghas Linn.), Ligtang (Anamirta cocculus), Kuisa (Quassia amara Linn.), Tuba shrub (Croton tiglium Linn.), Putat tree (Barringtonia racemosa), Saging-saging (Aegiceras corniculatum), Tubang bakod (Jatropa curcas Linn.), and Tubli shrub (Derris elliptica Benth).
ERDB Director Celso Diaz explained that familiarity with these plant species and their economic uses give many benefits to ranchers, stock raisers, veterinarians and foresters noting that "even with the presence of toxic substances, these plants are still beneficial and have special uses to human lives, animals and to other living organisms".
He, however, pointed out the need to increase public awareness of these plants and plant parts that are toxic.
Wood from paraiso is used for furniture and in making cabinets, plywood, boxes, tool handles, small articles and toys. The hard angular and bony centers of the fruit are removed by boiling, dyed and strung for beads.
Toxic substances from Adelfa, Baraibai, Ligtang, and Atis have been found to cause death, while the others give off substances that cause vomiting, blindness, paralysis and severe skin and throat irritation.
Effective for treating snakebites, herpes, and ringworm is the pounded bark and leaves of the Adelfa (Nerium indicum Mill.), commonly known as "baladre", Oleander tree or rose bay â€â€Âbut when ingested could also lead to vomiting , irregular heartbeat and death.
Seeds of the fruit of Baraibai tree (Cerbera manghas Linn.), also known as "buta-buta" or "marabai," provide oil called Odolla fat which is used as latex. The seeds when taken internally can likewise caused vomiting and death.
Extensively used for charcoal making, extracts from the bark of Baraibai tree are also used by fishermen to paralyze fish.
Another tree having highly poisonous substances found in its leaves, bark, wood, fruits, seeds and even roots is Ligtang, also known as "bayati" and "lantal". Its wood is widely used for knife handles, cabinets and fuel.
On the other hand, the toxic substances found in other plants cited have less lethal effect but are widely used as either insecticide or pesticide.
The seeds of Atis contain 45 percent of a yellow, non-drying oil which is an irritant or poison for lice. Crushed and pulverized seeds mixed with water or coconut oil can kill lice.
Kuisa, locally called "Korales," is propagated as an ornamental plant and is used in the production of medicines. It is also used as an additive for flavoring tonic wines and to accentuate the taste of marmalade. The Tuba shrub has similar properties and uses like the "Korales."
In Malaysia the plant extract is used as an insecticidal spray to kill flies and a decoction of the wood, done by boiling and allowing the decoction to stand overnight in a bowl mixed with molasses or sugar, makes an effective fly trap.
The wood and bark of the one of the hardiest Philippine wood, the Molave tree, have toxic substances that could cause internal bleeding if ingested, but have a curative effect on wounds and poisonous bites.
Of similar properties and uses is the Putat tree (Barringtonia racemosa). Extract from its bark is widely used by hunters in Ifugao and Mindanao to poison wild pigs. Its seeds also give off that is used as latex while its tree itself is usually used as hedges or fence posts in muddy places.
Another is the Tubli shrub (Derris elliptica Benth) for its wide-range of efficacy for agricultural and domestic application.
Tubli is found throughout the country and is commonly cultivated as a hedgeplant . It is presently cultivated in large plantation in Thailand for its seed which is a source of retonone.  Jasmin R. Uy/BRP