List of C4 plants


In botany, carbon fixation is one of three known methods of photosynthesis used by plants. plants increase their photosynthetic efficiency by reducing or suppressing photorespiration, which mainly occurs under low atmospheric concentration, high light, high temperature, drought, and salinity. There are roughly 8,100 known species, which belong to at least 61 distinct evolutionary lineages in 19 families of flowering plants. Among these are important crops such as maize, sorghum and sugarcane, but also weeds and invasive plants. Although only 3% of flowering plant species use carbon fixation, they account for 23% of global primary production. The repeated, convergent evolution from [C3 carbon fixation|] ancestors has spurred hopes to bio-engineer the pathway into crops such as rice.
photosynthesis probably first evolved 30–35 million years ago in the Oligocene, and further origins occurred since, most of them in the last 15 million years. plants are mainly found in tropical and warm-temperate regions, predominantly in open grasslands where they are often dominant. While most are graminoids, other growth forms such as forbs, vines, shrubs, and even some trees and aquatic plants are also known among plants.
plants are usually identified by their higher 13C/12C isotopic ratio compared to plants or their typical leaf anatomy. The distribution of lineages among plants has been determined through phylogenetics and was considered well known as of 2016. Monocots – mainly grasses and sedges – account for around 80% of species, but they are also found in the eudicots. Moreover, almost all plants are herbaceus, with the notable exception of some woody species from the Euphorbia genus, such as the tree Euphorbia olowaluana. The reason behind metabolism extreme rarity in trees is debated: hypotheses vary from a possible reduction in photosynthetic quantum yield under dense canopy conditions, coupled with an increased metabolic energy consumption, to less efficient sunflecks utilization.
The following list presents known lineages by family, based on the overview by Sage. They correspond to single species or clades thought to have acquired the pathway independently. In some lineages that also include and – intermediate species, the pathway may have evolved more than once.

Acanthaceae

The large acanthus family Acanthaceae includes one genus with species, found in dry habitats from Africa to Asia.

Aizoaceae

While many species in the ice plant family Aizoaceae use crassulacean acid metabolism, one subfamily with drought-tolerant and halophytic plants includes species:

Amaranthaceae

The amaranth family Amaranthaceae contains around 800 known species, which belong to 14 distinct lineages in seven subfamilies. This makes Amaranthaceae the family with most species and lineages among the eudicots. Suaeda aralocaspica and species of the genus Bienertia use a particular, single-cell type of carbon fixation.

Asteraceae

The composite family Asteraceae contains three lineages, in two different tribes of subfamily Asteroideae. They include the model genus Flaveria with closely related,, and intermediate species.

Boraginaceae

The borage family Boraginaceae contains one widespread genus, Euploca, which has also been treated as part of a distinct family Heliotropiaceae.
  • Euploca – 130 species, 1–3 origins

Cleomaceae

The Cleomaceae, formerly included in the caper family Capparaceae, contains three species in genus Cleome. These three species independently acquired the pathway; the genus also contains numerous as well as – intermediate species.

Caryophyllaceae

In the carnation family Caryophyllaceae, the pathway evolved once, in a clade within the polyphyletic genus Polycarpaea.

Cyperaceae

The sedge family Cyperaceae is second only to the grasses in number of species. Prominent sedges include culturally important species such as papyrus and chufa but also purple nutsedge, one of the world's major weeds. Eleocharis vivipara uses carbon fixation in underwater leaves and carbon fixation in aerial leaves.

Euphorbiaceae

The spurge family Euphorbiaceae contains the largest single lineage among eudicots. The spurges are diverse and widespread; they range from weedy herbs to the only known trees – four species from Hawaii, including Euphorbia olowaluana and E. herbstii.

Gisekiaceae

Contains a genus with a single species.

Hydrocharitaceae

Includes the only known aquatic plants.

Molluginaceae

The two species within the same genus have acquired the pathway independently.

Nyctaginaceae

Polygonaceae

Portulacaceae

The single genus of this family forms one lineage. CAM photosynthesis is also known. Common purslane is a major weed but also a vegetable.

Poaceae

The grass family includes most of the known species – around 5000. They are only found in subfamilies of the PACMAD clade. Major crops such as maize, sugarcane, sorghum and pearl millet belong in this family. The only known species with, and intermediate variants, Alloteropsis semialata, is a grass.

Scrophulariaceae

Zygophyllaceae