Plumeria

Plumerias are mildly toxic, not as much as their relative Nerium oleander. The plant's milky sap is irritant to skin to eyes. http://www2.ctahr.hawaii.edu/oc/freepubs/pdf/OF-24.pdf

Yes Cynthia this tree is not toxic. This tree will be found every house garden in rural and urban areas of India from many centuries.

I think the name you have listed is a bit misleading - this flower is used in abundance in Hawaii, for leis especially and is thought to be a welcoming flower not toxic. The name you have listed should be your description and change the name to Plumeria of Frangipani

seems the milk sap in the branches is poisonous but the flowers could be used as Chinese medicine~~

Can you explain what makes it toxic?

This flower smells beautiful mild fragrance.

Originated from Central America. Plumeria rubra is scientific name. Red, Maroon, Orange Maroon are other shades of flowers available in this plant. Well urbanized tree almost seen alive with 1 or 2 leafs on it.