Vessel element in the context of "Angiospermae"

Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (/ˌændʒiəˈspɜːrmiː/). The term angiosperm is derived from the Greek words ἀγγεῖον (angeion; 'container, vessel') and σπέρμα (sperma; 'seed'), meaning that the seeds are enclosed within a fruit. The group was formerly called Magnoliophyta.

Angiosperms are by far the most diverse group of land plants with 64 orders, 416 families, approximately 13,000 known genera and 300,000 known species. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of broad-leaved trees, shrubs and vines, and most aquatic plants. Angiosperms are distinguished from the other major seed plant clade, the gymnosperms, by having flowers, xylem consisting of vessel elements instead of tracheids, endosperm within their seeds, and fruits that completely envelop the seeds. The ancestors of flowering plants diverged from the common ancestor of all living gymnosperms before the end of the Carboniferous, over 300 million years ago. In the Cretaceous, angiosperms diversified explosively, becoming the dominant group of plants across the planet.

Softwood is wood from gymnosperm trees such as conifers. The term is opposed to hardwood, which is the wood from angiosperm trees. The main differences between hardwoods and softwoods is that the softwoods completely lack vessels (pores). The main softwood species (pines, spruces, larches, false tsugas) also have resin canals (or ducts) in their structure.

A tracheid is a long and tapered lignified cell in the xylem of vascular plants. It is a type of conductive cell called a tracheary element. Angiosperms also use another type of conductive cell, called vessel elements, to transport water through the xylem. The main functions of tracheid cells are to transport water and inorganic salts, and to provide structural support for trees. There are often pits on the cell walls of tracheids, which allows for water flow between cells. Tracheids are dead at functional maturity and do not have a protoplast. The wood (softwood) of gymnosperms such as pines and other conifers is mainly composed of tracheids. Tracheids are also the main conductive cells in the primary xylem of ferns.

The tracheid was first named by the German botanist Carl Gustav Sanio in 1863, from the German Tracheide.

Gnetophyta (/nɛˈtɒfɪtə, ˈnɛtoʊfaɪtə/) is a division of plants (alternatively considered the subclass Gnetidae or order Gnetales), grouped within the gymnosperms (which also includes conifers, cycads, and ginkgos), that consists of some 70 species across the three relict genera: Gnetum (family Gnetaceae), Welwitschia (family Welwitschiaceae), and Ephedra (family Ephedraceae). The earliest unambiguous records of the group date to the Jurassic, and they achieved their highest diversity during the Early Cretaceous. The primary difference between gnetophytes and other gymnosperms is the presence of vessel elements, a system of small tubes (xylem) that transport water within the plant, similar to those found in flowering plants. Because of this, gnetophytes were once thought to be the closest gymnosperm relatives to flowering plants, but more recent molecular studies have brought this hypothesis into question, with many recent phylogenies finding them to be nested within the conifers.

Though it is clear they are all related, the exact evolutionary inter-relationships between gnetophytes are unclear. Some classifications hold that all three genera should be placed in a single order (Gnetales), while other classifications say they should be distributed among three separate orders, each containing a single family and genus. Most morphological and molecular studies confirm that the genera Gnetum and Welwitschia diverged from each other more recently than they did from Ephedra.