Distribution, separated by genus: Green – Welwitschia Blue – Gnetum Red – Ephedra Purple – Gnetum and Ephedra
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.[1][2][3][4][5]
Welwitschia mirabilis bearing male conesEphedra distachya (male cones)Ephedra distachya (female plant in bloom)Gnetum gnemon male strobiliGnetum gnemon female strobilusFemale Ephedra californica cone
^Peter R. Crane; Patrick Herendeen; Else Marie Friis (2004). "Fossils and plant phylogeny". American Journal of Botany. 91 (10): 1683–1699. doi:10.3732/ajb.91.10.1683. PMID 21652317.
^Cite error: The named reference Bowe was invoked but never defined (see the help page).
^Gugerli, F.; Sperisen, C.; Buchler, U.; Brunner, L.; Brodbeck, S.; Palmer, J.D.; Qiu, Y.L. (2001). "The evolutionary split of Pinaceae from other conifers: evidence from an intron loss and a multigene phylogeny". Molecular Phylogenetics and Evolution. 21 (2): 167–175. doi:10.1006/mpev.2001.1004. PMID 11697913.
^Rai, H.S.; Reeves, P.A.; Peakall, R.; Olmstead, R.G.; Graham, S.W. (2008). "Inference of higher-order conifer relationships from a multi-locus plastid data set". Botany. 86 (7): 658–669. doi:10.1139/B08-062.
^Ickert-Bond, S. M.; C. Rydin & S. S. Renner (2009). "A fossil-calibrated relaxed clock for Ephedra indicates an Oligocene age for the divergence of Asian and New World clades, and Miocene dispersal into South America" (PDF). Journal of Systematics and Evolution. 47 (5): 444–456. doi:10.1111/j.1759-6831.2009.00053.x. S2CID 55148071.
Gnetophyta (/nɛˈtɒfɪtə, ˈnɛtoʊfaɪtə/) is a division of plants (alternatively considered the subclass Gnetidae or order Gnetales), grouped within the gymnosperms...
Welwitschiaceae and order Welwitschiales in the division Gnetophyta, and is one of three living genera in Gnetophyta, alongside Gnetum and Ephedra. Informal sources...
Pinophyta, the conifers, which are cone-bearing trees and shrubs, and Gnetophyta, the gnetophytes, various woody plants in the relict genera Ephedra, Gnetum...
3 celled pollen grains while Ginkgophyta have 4 celled pollen grains. Gnetophyta may have 2 or 3 celled pollen grains depending on the species, and Coniferophyta...
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...
genus of gymnosperms, the sole genus in the family Gnetaceae within the Gnetophyta. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms...
angiosperms and four divisions of gymnosperms: the Cycadophyta, Ginkgophyta, Gnetophyta, and Pinophyta (also known as Coniferophyta). Newer classification place...
related to the Ginkgophyta). Multiple studies also indicate that the Gnetophyta belong within the conifers despite their distinct appearances, either...
the stem. Some families and genera containing liana species include: Gnetophyta Gnetum Acanthaceae Mendoncia Thunbergia, such as T. grandiflora and T...
nutrients for the developing sperm cells. Sperm cells of Pinophyta and Gnetophyta are without flagella, and are carried by the pollen tube, while those...
The Ciechocinek Formation is a Jurassic (lower to middle Toarcian) geologic formation which extends across the Baltic coast from Grimmen, Germany, to Nida...
stem. Ovules are produced on the adaxial surface of the cone scales. Gnetophyta consists of three genera, Ephedra, Gnetum and Welwitschia. All three are...
extinct taxa, and within extinct taxa, and particularly the placement of Gnetophyta. The latter have been variously classified as basal to all gymnosperms...
contrast to previous classifications placing it outside the conifers, Gnetophyta may in fact be the sister group to the Pinaceae, with both lineages having...
Although secondary xylem is also found in members of the gymnosperm groups Gnetophyta and Ginkgophyta and to a lesser extent in members of the Cycadophyta,...
This list of 2013 in paleobotany records new fossil plant taxa that were described during 2013, as well as other significant discoveries and events related...
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