There are over 300,000 types of plants in several large groups. There are slightly different classification systems for plants, but most recognize two basic groups, the nonvascular plants, and the vascular plants. The vascular plants can either be herbaceous or woody. 

Herbaceous plants do not have specialized woody tissue for water transportation from the roots to the shoots.   Woody plants have conducting tissues called xylem and phloem tissues.  Xylem tissue transports water and phloem tissue transports food products. These tissues are absent in herbaceous vascular plants and  nonvascular plants. 

Nonvascular plants in the classification used in this curriculum include the Thallophytes (green algae,  brown-green algae, brown-red algae) and Bryophytes (mosses, and liverworts). Vascular plants or Tracheophytes include ferns (filicopsids), sphenopsids (horse tails), gymnosperms (needle leaves), and angiosperms (flowering plants). Nonvascular plants are sometimes referred to as thallus.