Most plants are multicellular organisms. However, some unicellular organisms have plant-like characteristics. The list of basic multicellular organisms is as given below:
Ä Tree
Ä Herbs
Ä Bush/Shrub
Ä Grass
Ä Vines
Ä Fern
Ä Moss
Ä Fern Ally
Ä Algae
Ä Fungi

Although, fern, fern ally, algae are the part of classification of Kingdom: Plantae it is considered as a multicellular plant organism as well as fungal species have plant-like characteristics.

To see the list of plant organs click here