Chloridoideae is one of the largest

subfamilies In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zool ...

grasses Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivated in ...

, with roughly 150 genera and 1,600 species, mainly found in

arid Aridity is the condition of geographical regions which make up approximately 43% of total global available land area, characterized by low annual precipitation, increased temperatures, and limited water availability.Perez-Aguilar, L. Y., Plata ...

tropical or subtropical

grasslands A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes such as clover, and other herbs. Grasslands occur ...

. Within the

PACMAD clade The PACMAD clade (previously PACCMAD, PACCAD, or PACC) is one of two major lineages (or clades) of the true grasses (Poaceae), regrouping six subfamilies and about 5700 species, more than half of all true grasses. Its sister group is the BOP cla ...

, their

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

is the

Danthonioideae Danthonioideae is a mainly southern hemisphere subfamily of grasses, containing the single tribe Danthonieae and one unplaced genus, with altogether roughly 300 species. It includes herbaceous to partially woody perennial or annual (less common) ...

. The subfamily includes widespread

weed A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...

s such as Bermuda grass (''

Cynodon dactylon ''Cynodon dactylon'', commonly known as Bermuda grass, also known as couch grass in Australia and New Zealand, is a grass found worldwide. It is native to Europe, Africa, Australia and much of Asia. It has been introduced to the Americas. Contra ...

''), goosegrass ('' Eleusine indica'') or finger grass (''

Chloris In Greek mythology, the name Chloris (; Greek Χλωρίς ''Chlōrís'', from χλωρός ''chlōrós'', meaning "greenish-yellow", "pale green", "pale", "pallid", or "fresh") appears in a variety of contexts. Some clearly refer to different ch ...

''), but also

millet Millets () are a highly varied group of small-seeded grasses, widely grown around the world as cereal crops or grains for fodder and human food. Most millets belong to the tribe Paniceae. Millets are important crops in the Semi-arid climate, ...

species grown in some tropical regions, namely finger millet (''

Eleusine coracana Finger millet (''Eleusine coracana'') is an annual herbaceous plant widely grown as a cereal crop in the arid and semiarid areas in Africa and Asia. It is a tetraploid and self-pollinating species probably evolved from its wild relative ''Ele ...

'') and teff (''

Eragrostis tef ''Teff'' (), also known as ''Eragrostis tef'', Williams lovegrass, or annual bunch grass, is an annual plant, annual Poaceae, grass, a species of lovegrass native to Ethiopia, where it first originated in the Ethiopian Highlands. It is cultivate ...

''). With the exception of some species in ''

Ellisochloa ''Ellisochloa'' is a genus of Namibian and South African plants in the Poaceae, grass family. ; Species * ''Ellisochloa papposa'' (Nees) P.M.Peterson & N.P.Barker - Cape Province * ''Ellisochloa rangei'' (Pilg.) P.M.Peterson & N.P.Barker - Namib ...

'' and '' Eleusine indica'', most of the subfamily's species use the C₄ photosynthetic pathway. The first evolutionary transition from C₃ to C₄ photosynthesis in the grasses probably occurred in this subfamily, around 32 to 25 million years ago in the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

Phylogeny

Relationships of tribes in the Chloridoideae according to a 2017

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

classification, also showing the Danthonioideae as sister group: The following genera have not been assigned to a tribe: *'' Gossweilerochloa'' *'' Indopoa'' *'' Lepturopetium'' *'' Myriostachya'' *'' Pogonochloa'' *'' Pseudozoysia'' *'' Silentvalleya''

References

* * Poaceae subfamilies {{Chloridoideae-stub