Gnetophyta in the context of "Acrogymnosperm"

The gymnosperms (/ˈdʒɪmnəˌspɜːrmz, -noʊ-/ nə-spurmz, -⁠noh-; from Ancient Greek γυμνός (gumnós), meaning "naked", and σπέρμα (spérma), meaning "seed", and thus, "naked seed") are a group of woody, perennial seed-producing plants, typically lacking the protective outer covering which surrounds the seeds in flowering plants, that include conifers, cycads, Ginkgo, and gnetophytes, forming the clade Gymnospermae. The name is based on the unenclosed condition of their seeds (called ovules in their unfertilized state). The non-encased condition of their seeds contrasts with the seeds and ovules of flowering plants (angiosperms), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, which are often modified to form cones, or on their own as in yew, Torreya, and Ginkgo.

The life cycle of a gymnosperm involves alternation of generations, with a dominant diploid sporophyte phase, and a reduced haploid gametophyte phase, which is dependent on the sporophytic phase. The term "gymnosperm" is often used in paleobotany to refer to (the paraphyletic group of) all non-angiosperm seed plants. In that case, to specify the modern monophyletic group of gymnosperms, the term Acrogymnospermae is sometimes used.

Bennettitales (also known as cycadeoids) is an extinct order of seed plants that first appeared in the Permian period and became extinct in most areas toward the end of the Cretaceous. Bennettitales were amongst the most common seed plants of the Mesozoic, and had morphologies including shrub and cycad-like forms. The foliage of bennettitaleans is superficially nearly indistinguishable from that of cycads, but they are distinguished from cycads by their more complex flower-like reproductive organs, at least some of which were likely pollinated by insects.

Although certainly gymnosperms sensu lato (cone-bearing seed plants), the relationships of bennettitaleans to other seed plants is debated. Their general resemblance to cycads is contradicted by numerous more subtle features of their reproductive systems and leaf structure. Some authors have linked bennettitaleans to angiosperms (flowering plants) and gnetophytes (a rare and unusual group of modern gymnosperms), forming a broader group known as Anthophyta. Molecular data contradicts this, with gnetophytes found to be much more genetically similar to conifers. The exact position of Bennettitales remains uncertain.

Ephedra is a genus of gymnosperm shrubs. As of July 2025, 74 species, and two hybrids, are accepted. The species of Ephedra are widespread in many arid regions of the world, ranging across southwestern North America, southern Europe, northern Africa, southwest and central Asia, northern China, and western South America. It is the only extant genus in its family, Ephedraceae, and order, Ephedrales, and one of the three extant genera of the division Gnetophyta together with Gnetum and Welwitschia.

In temperate climates, most Ephedra species grow on shores or in sandy soils with direct sun exposure. Common names in English include joint-pine, jointfir, Mormon-tea, or Brigham tea. The Chinese name for Ephedra species is mahuang (simplified Chinese: 麻黄; traditional Chinese: 麻黃; pinyin: máhuáng; Wade–Giles: ma-huang; lit. 'hemp yellow'). Ephedra is the origin of the name of the stimulant ephedrine, which the plants contain in significant concentration.

Gnetum is a genus of gymnosperms, the sole genus in the family Gnetaceae within the Gnetophyta. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms, they possess vessel elements in the xylem. Some species have been proposed to have been the first plants to be insect-pollinated as their fossils occur in association with extinct pollinating scorpionflies. Molecular phylogenies based on nuclear and plastid sequences from most of the species indicate hybridization among some of the Southeast Asian species. Fossil-calibrated molecular-clocks suggest that the Gnetum lineages now found in Africa, South America and Southeast Asia are the result of ancient long-distance dispersal across seawater.

Their leaves are rich in phytochemicals such as flavonoids and stilbenes. Of the species studied so far, Gnetum have photosynthetic and transpiration capacities which are considerably lower than those of other seed plants, due to the absence of multiple chloroplast genes essential for photosynthesis, a trait they seem to share with the other living members of Gnetophyta, Ephedra and Welwitschia, as well as conifers. There are over 50 different species of Gnetum.

Welwitschia is a monotypic genus of gnetophytes containing only the species Welwitschia mirabilis. It is named after the Austrian botanist Friedrich Welwitsch, who documented the plant in the 1850s. In common use, it is sometimes referred to as the tree tumbo. It is native to Angola and Namibia, where it grows in the extreme conditions of the Namib desert, tolerating high heat and low precipitation. Welwitschia is the only living genus of the family Welwitschiaceae and order Welwitschiales, and is one of three extant genera of gnetophytes, alongside Gnetum and Ephedra.

Welwitschia is well known for its unique morphology. The plant has only two leaves that grow out of a large woody stem, known as a crown, and continue to grow throughout the plant's life. Welwitschia is one of the longest-living plants on Earth, with some individuals being thousands of years old. Because of the long lifespan the leaves can become quite large, often reaching several meters in length.

Ephedraceae is a family of gymnosperms belonging to Gnetophyta, it contains only a single extant genus, Ephedra, as well as a number of extinct genera from the Early Cretaceous.