Yes,it is true that plants have hypodermis and endodermis.
See,like we animals,plants also have a well-defined (and somewhat complex) tissue system.And that too there are different types of tissues systems in different parts of the plant.(And you are right-epidermis is the outermost layer being common in root,stem or leaf).It depends on which one you want to know?Root,stem or leaves?
OK,so let me briefly tell about the tissue system in a stem-
(Following data are very brief,please study about the anatomy of a typical plant body first to understand the following points clearly! :-))
1) Epidermis: Outermost protective thin layer of the stem(just like the epidermis of or skin-kind-of-analogy!)
Note:- Hypodermis and endodermis are the layers present in the cortex region of a stem
2) Hypodermis: This layer consists of collenchymatous cells-which are used to provide mechanical strength-esp. for young stems.
3) Endodermis: This is the innermost layer of the cortex-which contains starch grains and hence this layer is also known as "Starch Sheath" because of this.
Please if you want to know about all this in detail (with the anatomy of a typical stem-please go through the following site- http://www.botany.uwc.ac.za/sci_ed/grad … /stems.htm)