I would like to know botanical names of trees, plants, flowers, etc to teach my son. Where from I can get ?

The library, a bookstore, the internet? I'm not into doing the shopping/searching for you, however...

Botanic gardens with gift shops will have the best beginning to technical plant identification guides for amateurs, professionals, gardeners, and farmers. Taxonomic keys are used by professionals - it takes considerable training to use these. Picture books are easier. Consider the types of plants you are interested in - native plants, local plants, crops, weeds, grasses, garden plants, orchids or oaks. There will be a book on it.

If you don't have a local botanic garden, try a museum, or your local university bookstore, especially one that teaches natural history or botany.

The internet is a great resource for plant id.