Belongs within: Poaceae.
Contains: Triraphideae, Zoysieae, Cotteinae, Uniolinae, Eragrostis, Triodia, Orcuttiinae, Gouiniinae, Eleusininae, Tripogoninae, Pappophorinae, Bouteloua, Muhlenbergia, Hilaria.
The Chloridoideae are a clade of mostly C4 grasses supported by molecular analysis but with unclear morphological synapomorphies. The clade of chloridoids excluding Centropodieae may be supported by the presence of ‘chloridoid-type’ microhairs with short and wide apical cells (Grass Phylogeny Working Group 2001). With the exception of Ellisochloa rangei, chloridoids exhibit radiate chlorenchyma around the veins and C4 photosynthesis (Kellogg 2015).
Subgroups include the Centropodieae which are perennial grasses bearing branched inflorescences and nine-veined lemmas with tufted hairs in a a tufted row, and awned from the sinus (Kellogg 2015). The Eragrostideae bear laterally compressed spikelets with distal flowers often reduced, and often short glumes lacking awns (Kellogg 2015).
The Cynodonteae are a diverse clade strongly united by molecular data but without clear synapomorphies (Kellogg 2015). Dactyloctenium species have digitate spikes with the axis of the spikes terminating in a short point (Gardner 1952). The Boutelouinae generally have the ligule as a fringed membrane, and inflorescences are usually unbranched or have unbranched branches (Kellogg 2015). Distichlis, the saltgrasses, are rhizomatous or stoloniferous grasses with conspicuously distichous leaves (Hickman 1993).
Characters (Kellogg 2015): Plants herbaceous. Annuals or perennials, caespitose, rhizomatous or stoloniferous, erect or decumbent. Culms hollow or solid. Ligule membranous, or a fringed membrane, or a fringe of hairs. Leaf blades lacking pseudopetioles or auricles. Inflorescences unbranched, or with unbranched primary branches, or with branched primary branches. Spikelets laterally compressed, with one to many flowers, proximal ones fertile, distal ones (if present) often reduced. Glumes 2, disarticulation above glumes. Lemmas bilobed, awned from the sinus. Lodicules 2, fleshy. Caryopsis with pericarp fused to seed coat; hilum short, punctate; embryo with an epiblast, with a scutellar cleft, with an elongated mesocotyl internode, with embryonic leaf margins not overlapping. Midrib anatomy simple. Mesophyll radiate, with a double bundle sheath. Usually C4. Bicellular microhairs with distal cell narrow and elongate (“panicoid type”) to nearly spherical (“chloridoid type”).
<==Chloridoideae [Eragrostoideae, Pappophoroideae]
|--CentropodieaeK15
| |--Centropodia Rchb. 1828GPWG01, K15
| | `--C. glaucaGPWG01
| `--Ellisochloa Peterson & Barker 2011K15
| |--E. papposa [=Merxmuellera papposa]K15
| `--E. rangeiK15 [=Merxmuellera rangeiGPWG01]
`--+--TriraphideaeK15
`--+--ZoysieaeS06
|--EragrostideaeGPWG01
| | i. s.: Cladoraphis Franch. 1887K15
| | `--C. spinosaK15
| | Tetrachaete Chiov. 1903K15
| | `--T. elionuroidesK15
| |--CotteinaeK15
| |--UniolinaeK15
| `--EragrostidinaeK15
| |--EragrostisK15
| |--Steirachne Ekman 1911K15
| |--Catalepis Stapf & Stent 1929K15
| | `--C. gracilisK15
| |--Richardsiella Elffers & Kenn.-O’Byrne 1957K15
| | `--R. eruciformisK15
| `--Heterachne Benth. 1877K15
| |--H. browniiB78 [incl. H. abortivaLK14, Poa abortivaB78]
| `--H. gulliveri Benth. 1877G52
| |--H. g. var. gulliveriLK14
| `--H. g. var. majorLK14
`--Cynodonteae [Chlorideae, Tridentinae]CM15
| i. s.: Cleistogenes Keng 1934 [incl. Kengia Packer 1960 (nom. illeg.)]K15
| `--C. serotinaH91
| Hubbardochloa Auquier 1980K15
| `--H. gracilisK15
| Lepturidium Hitchc. & Ekman 1936K15
| `--L. insulareK15
| Orinus Hitchc. 1933K15
| Pogoneura Napper 1963K15
| `--P. bifloraK15
| Pommereulla L. f. 1780K15
| `--P. cornucopiaeK15
|--TriodiaCM15
|--OrcuttiinaeK15
|--GouiniinaeK15
|--EleusininaeK15
|--TripogoninaeK15
|--PappophorinaeK15
|--AeluropodinaeCM15
| |--Aeluropus Trin. 1820K15
| `--+--Brachychloa Phillips 1982K15
| |--Neobouteloua Gould 1968K15
| |--Odyssea Stapf 1922CM15, K15
| `--Dactyloctenium Willd. 1809K15
| |--D. aegyptium (Lin.) Richter 1890S06 (see below for synonymy)
| |--D. mucronatumC55
| |--D. radulans (Br.) Beauv. 1812G52 [=Eleusine radulansB78; incl. D. australienseG52]
| `--D. scindicumPP07
`--Boutelouinae [Hilariinae, Monanthochloinae, Muhlenbergiinae, Scleropogoninae, Traginae]K15
|--BoutelouaK15
|--MuhlenbergiaK15
|--HilariaK15
|--Jouvea Fourn. 1876K15
|--Allolepis Soderst. & Decker 1965K15
| `--A. texanaK15
|--Sohnsia Airy Shaw 1965K15
| `--S. filifoliaK15
|--Distichlis Raf. 1819 [incl. Monanthochloe Engelm. 1859, Reederochloa Soderstr. & Decker 1964]K15
| |--‘Monanthochloe’ littoralisH93
| |--D. scopariaS06
| `--D. spicata (Linnaeus) Greene 1887S06 (see below for synonymy)
| | i. s.: D. s. f. hirta [=D. hirta Phil. 1873]S06
| | D. s. var. mendozina [=D. thalassica var. mendozina]S06
| | D. s. var. thalassicaS06 (see below for synonymy)
| |--D. s. ssp. spicataGPWG01
| `--D. s. ssp. strictaGPWG01
|--+--Monelytrum Hack. 1888K15
| | `--M. leuderitzianumK15
| |--+--Willkommia Hack. 1888K15
| | `--Polevansia de Winter 1966K15
| | `--P. rigidaK15
| `--Tragus Haller 1768 (nom. cons.)K15
| |--T. australiensis Blake 1941G52
| |--T. decipiensD17
| |--T. racemosusS06 [=Lappago racemosaB78]
| | |--T. r. var. racemosusS06
| | `--T. r. var. berteronianusS06
| `--T. roxburghiiPP07
`--+--Blepharidachne Hack. 1887K15
|--Scleropogon Phil. 1870K15
| `--S. brevifoliusH93
|--Swallenia Soderstr. & Decker 1963K15
| `--S. alexandrae [=Ectosperma alexandrae]H93
`--+--Erioneuron Nash 1903K15
| |--E. pilosum [=Tridens pilosus]H93
| `--E. pulchellum [=Tridens pulchellus]H93
`--Munroa Torr. 1857 [incl. Dasyochloa Willd. ex Rydb. 1906]K15
|--M. argentinaK15
|--M. benthamianaS06
|--‘Dasyochloa’ pulchellaHW96
`--M. squarrosa [incl. M. mendocina]S06
Chloridoideae incertae sedis:
Decaryella Camus 1931 non Séguy 1926K15
`--D. madagascariensisK15
Halopyrum Stapf 1896K15
`--H. mucronatumK15
Indopoa Bor 1958K15
`--I. pauperculaK15
Kampochloa Clayton 1967K15
`--K. brachyphyllaK15
Lepturopetium Morat 1981K15
Myriostachya (Benth.) Hook. f. 1897K15
`--M. wightianaK15
Neostapfiella Camus 1926K15
Ochthochloa Edgew. 1842K15
`--O. compressaPP07
Pogonochloa Hubb. 1940K15
`--P. greenwayiK15
Pseudozoysia Chiov. 1928K15
`--P. sessilisK15
Silentvalleya Nair, Sreek. et al. 1982K15
`--S. nairiiK15
Viguierella Camus 1926K15
`--V. madagascariensisK15
Dactyloctenium aegyptium (Lin.) Richter 1890S06 [=Cynosurus aegyptius Lin. 1753S06, Eleusine aegyptia (Lin.) Pers. 1805S06; incl. Dactyloctenium aegyptiacum Willd. 1809S06, E. cruciataB78]
Distichlis spicata (Linnaeus) Greene 1887S06 [=Uniola spicata Linnaeus 1853S06, Brizopyrum spicatumS06; incl. Poa distichophyllaB78, Festuca distichophyllaB78, Uniola distichophyllaS06, Distichlis spicata var. divaricataH93, D. maritima Rafin. 1819S06, Poa michauxiiS06, D. spicata var. nanaH93, P. paradoxaB78, D. spicata var. stoloniferaH93]
Distichlis spicata var. thalassicaS06 [=Megastachya thalassicaS06, Poa thalassicaB78, Uniola thalassicaS06]
*Type species of generic name indicated
References
[B78] Bentham, G. 1878. Flora Australiensis: A description of the plants of the Australian Territory vol. 7. Roxburghiaceae to Filices. L. Reeve & Co.: London.
[C55] Candolle, A. de. 1855. Géographie Botanique Raisonée: Ou exposition des faits principaux et des lois concernant la distribution géographique des plantes de l’époque actuelle vol. 2. Librairie de Victor Masson: Paris.
[CM15] Crisp, M. D., J. Mant, A. Toon & L. G. Cook. 2015. Australian spinifex grasses: new names in Triodia for Monodia and Symplectrodia. Phytotaxa 230 (3): 293–296.
[D17] Diels, L. 1917. Beiträge zur Flora der Zentral-Sahara und ihrer Pflanzengeographie. Nach der Sammelausbeute des Freiherrn Hans Geyr von Schweppenburg. Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie 54 (Beiblatt 120): 51–155.
[G52] Gardner, C. A. 1952. Flora of Western Australia vol. 1 pt 1. Gramineae. William H. Wyatt: Perth.
[GPWG01] Grass Phylogeny Working Group. 2001. Phylogeny and subfamilial classification of the grasses (Poaceae). Annals of the Missouri Botanical Garden 88 (3): 373–457.
[H93] Hickman, J. C. (ed.) 1993. The Jepson Manual: Higher Plants of California. University of California Press: Berkeley (California).
[HW96] Hicks, A. L., & R. F. Whitcomb. 1996. Diversity of the leafhopper (Homoptera: Cicadellidae) fauna of northern Chihuahuan grasslands, with emphasis on gypsum grasslands and description of a new species of Athysanella (Cicadellidae: Deltocephalinae). Proceedings of the Entomological Society of Washington 98 (1): 145–157.
[H91] Hubálek, Z. 1991. Biogeographic indication of natural foci of tick-borne infections. In: Dusbábek, F., & V. Bukva (eds) Modern Acarology: Proceedings of the VIII International Congress of Acarology, held in České Budĕjovice, Czechoslovakia, 6–11 August 1990 vol. 1 pp. 255–260. SPB Academic Publishing: The Hague.
[K15] Kellogg, E. A. 2015. The Families and Genera of Vascular Plants vol. 13. Flowering Plants: Monocots: Poaceae. Springer.
[LK14] Lyons, M. N., G. J. Keighery, L. A. Gibson & T. Handasyde. 2014. Flora and vegetation communities of selected islands off the Kimberley coast of Western Australia. Records of the Western Australian Museum Supplement 81: 205–244.
[PP07] Pandey, R. P., & P. M. Padhye. 2007. Studies on phytodiversity of Arid Machia Safari Park-Kailana in Jodhpur (Rajasthan). Bulletin of the Botanical Survey of India 4: 15–78.
[S06] Stuckert, T. 1906. Segunda contribución al conocimiento de las gramináceas Argentinas. Anales del Museo Nacional de Buenos Aires, serie 3, 6: 409–555.