The Subkingdom Tracheobionta
encompasses those plants
in the Kingdom Plantae
that have specialized cells for conducting water and sap within their tissues. Thus, the term vascular plants
meaning a network of conducting vessels — refers to the grouping inclusive of flowering plants
, conifers and allies (former gymnosperms), and ferns
, but not mosses or more "primitive" plants collectively called the nonvascular plants.
These plants are differentiated from the nonvascular plants in two important ways:
- Vascular plants have water-carrying tissues, termed tracheids, in their tissues, enabling the plants to evolve larger and more elaborate structures, while non-vascular plants lack these.
- In vascular plants, the principal generation phase is the sporophyte, which is diploid with two sets of chromosomes per cell. In non-vascular plants, the principal generation phase is often the gametophyte, which is haploid with one set of chromosomes per cell. See also alternation of generations.
Vascular plants used to be grouped in the Division Tracheophyta
. While certainly a monophyletic
group, tracheophytes just aren't closely related enough to warrant a single division for all of them.