Vascular Plant

Vascular plants, also known as tracheophytes, constitute the dominant group of land plants and include the vast majority of extant embryophyte species. They are characterised by the presence of lignified xylem for transporting water and minerals, and non-lignified phloem for distributing the products of photosynthesis. The group encompasses clubmosses, horsetails, ferns, gymnosperms such as conifers, and angiosperms, the flowering plants. They stand in contrast to non-vascular plants, including mosses and many green algae, which lack these specialised conducting tissues. Scientific names applied to vascular plants include Tracheophyta, Tracheobionta, and Equisetopsida sensu lato. Early land plants such as the rhyniophytes possessed only rudimentary vascular structures; the term eutracheophyte is used to identify all other vascular plants, including all modern representatives.

Characteristics

Botanists generally describe vascular plants according to three key diagnostic features.
First, they possess vascular tissues consisting of xylem and phloem arranged in vascular bundles. Xylem contains lignified cells that conduct water and dissolved minerals from roots to shoots. Phloem contains living sieve-tube elements that transport organic nutrients produced by photosynthesis. The evolution of such conducting tissues allowed vascular plants to achieve much larger sizes than non-vascular plants in which transport functions rely on diffusion or basic cellular conduction.
Second, vascular plants are defined by the dominance of the sporophyte generation in their life cycle. The sporophyte is diploid and produces spores via meiosis, while the gametophyte is typically reduced in size and complexity. This stands in contrast to non-vascular plants, in which the haploid gametophyte is the principal phase. The shift towards sporophyte dominance is thought to be associated with improved dispersal and survival of spores, aided by more robust and elaborated diploid tissues.
Third, vascular plants possess true roots, stems, and leaves, although some lineages have secondarily lost one or more of these structures. Roots enable efficient water and nutrient uptake, stems provide support and transport pathways, and leaves maximise the surface area available for photosynthesis. Cavalier-Smith treated Tracheophyta as a division defined by the presence of a diploid phase equipped with xylem and phloem, encapsulated in the Latin description facies diploida xylem et phloem instructa.
Sexual reproduction in vascular plants involves meiosis within reproductive tissues, producing spores whose development includes pathways for repairing DNA damage, including oxidative lesions, thereby safeguarding genetic continuity.

Phylogeny

Phylogenetic reconstructions place vascular plants within a well-supported clade that evolved from early land plants possessing simple conducting tissues. A commonly cited phylogeny, following work by Kenrick and Crane (1997) with later updates from Christenhusz, Smith, and others, distinguishes the rhyniophytes from the eutracheophytes. Within the latter, lycophytes form an early-diverging lineage, followed by ferns and seed plants.
Molecular studies generally support these relationships, although alternative arrangements have been proposed when fossil evidence is included. Some researchers argue, for example, that the traditional fern group (Pteridophyta) is not monophyletic. Hao and Xue have offered alternative placements for pre-euphyllophyte plants, highlighting the complexity of early vascular evolution.

Nutrient Distribution

Vascular tissues play central roles in the transport of water, minerals, and organic compounds.
Water and inorganic nutrients are absorbed by the roots and carried upward through xylem. In flowering plants the xylem contains vessel elements, while other vascular groups rely on tracheids. These cells are dead at maturity, possess lignified walls, and form long axial files that create continuous conduits.
Carbohydrates such as sucrose, generated through photosynthesis in leaves, are transported through phloem. Sieve-tube members are living cells lacking nuclei and many organelles; their metabolic requirements are supported by adjacent companion cells. Flow through the phloem is facilitated by sieve plates, perforated structures that allow movement of solutes between connected elements.

Transpiration

Water movement in vascular plants is primarily driven by transpiration, the evaporation of water from stomata, which generates a tension that pulls water through the xylem. Hydrogen bonding between water molecules produces a cohesive column extending from the roots to the leaves. As water evaporates from the mesophyll cell walls, the resulting tension draws more water upwards. This process is largely passive and requires little direct metabolic energy.
Transpiration is closely linked to nutrient absorption, as dissolved minerals travel with the water stream. Plants regulate stomatal opening to balance water conservation with the need for photosynthesis and nutrient transport. At night, or under conditions of high humidity or drought, transpiration diminishes, and root pressure may accumulate, sometimes leading to the excretion of excess water through hydathodes.

Absorption and Conduction

Water uptake by roots occurs primarily through osmosis. Root pressure fluctuates with the rate of transpiration, increasing under low transpiration conditions and declining when demand is high. When evapotranspiration is negligible, little water ascends the plant.
Conduction incorporates both upward transport through xylem and bidirectional transport through phloem. Sugars produced in leaves (sources) are delivered to growing tissues or storage organs (sinks), enabling growth, respiration, and accumulation of reserves. Minerals taken up at the roots travel to meristematic tissues where they support cell division and differentiation. Secondary xylem, formed through growth, constitutes the bulk material of timber and underpins major forest industries.