Belongs within: Poeae.
Poa is a genus of more than 500 species of grasses, including meadow-grasses and bluegrasses, found in temperate regions of both hemispheres as well as on tropical mountains. Notable species include P. annua, annual bluegrass, which is commonly used for lawns and animal fodder.
The greater number of species are perennial though members of the sections Ochlopoa and Diversipoa are largely annual. Spikelets of Ochlopoa have the callus glabrous whereas in Diversipoa it bears cobwebby hairs. In the cosmopolitan P. annua, the spikelet axis is generally hidden. Poa compressa is a rhizomatous perennial with distinctly compressed, wiry stems and nodes. Species of section Madropoa have leaves with firm, inrolled blades and generally unisexual flowers (Hickman 1993). Bulbous bluegrass P. bulbosa is a densely caespitose species with bulbous stem bases and most florets replaced by leafy bulblets (Hickman 1993).
Characters (Kellogg 2015): Perennials or annuals, caespitose, rhizomatous, or stoloniferous; plants bisexual, monoecious, dioecious, or gynodioecious. Spikelets with (1) 2 to 6 (13) flowers; rachilla extension present or absent. Glumes generally shorter than flowers, rarely longer, their apices obtuse to acuminate, sometimes muticous, rarely mucronate. Callus of flower glabrous, or with long cobweb-like hairs, or with a tuft of hairs. Lemma with a strong keel in many species, rounded in others, rarely flabellate, apex obtuse to acuminate, generally awnless. 2n = 14, 28, 42, 56, 70, as well as virtually all aneuploid numbers up to and including 147.
<==Poa L. 1753 (see below for synonymy)K15
|--P. × limosa [P. pratensis × P. secunda ssp. juncifolia; incl. P. fibrata]H93
|--P. nervosa complexH93
| |--P. rhizomataH93
| `--P. sierraeH93
|--P. (sect. Poa) pratensisH93
| |--P. p. ssp. pratensisH93
| |--P. p. ssp. agassizensisH93
| `--P. p. ssp. angustifoliaH93
|--P. sect. AbbreviataeH93
| |--P. keckiiH93
| |--P. lettermaniiH93
| `--P. pattersoniiH93
|--P. (sect. Coenopoa) trivialisH93
|--P. sect. DiversipoaH93
| |--P. bigeloviiH93
| |--P. bolanderiH93
| `--P. howellii [=P. bolanderi ssp. howellii]H93
|--P. sect. MadropoaH93
| | i. s.: P. atropurpureaH93
| | P. confinisH93
| | P. douglasiiH93
| | P. fendlerianaH93
| | |--P. f. ssp. fendlerianaH93
| | `--P. f. ssp. longiligulaH93
| | P. macrantha [=P. douglasii ssp. macrantha]H93
| | P. piperiH93
| `--P. subsect. EpilesH93
| |--P. cusickiiH93
| | |--P. c. ssp. cusickii [incl. P. hansenii]H93
| | |--P. c. ssp. epilisH93
| | |--P. c. ssp. pallidaH93
| | `--P. c. ssp. purpurascensH93
| |--P. pringleiH93
| `--P. stebbinsiiH93
|--P. sect. OchlopoaH93
| |--P. annuaH93
| `--P. infirmaH93
|--P. (sect. Oreinos) leptocomaH93
|--P. sect. SecundaeH93
| | i. s.: P. secundaH93
| | |--P. s. ssp. secunda [incl. P. canbyi, P. gracillima, P. incurva, P. sandbergii, P. scabrella]H93
| | `--P. s. ssp. juncifolia [incl. P. ampla, P. nevadensis]H93
| | P. tenerrimaH93
| `--P. subsect. HalophytaeH93
| |--P. napensisH93
| `--P. unilateralis [incl. P. pachypholis]H93
|--P. sect. StenopoaH93
| |--P. glaucaH93
| | |--P. g. ssp. glaucaH93
| | `--P. g. ssp. rupicolaH93
| |--P. nemoralisH93
| | |--P. n. var. nemoralisD03
| | `--P. n. var. magellanicaD03
| `--P. palustrisVB02
`--P. (sect. Tichopoa) compressaH93
Poa incertae sedis:
P. abbreviataD60
P. acicularifoliaC06
P. aitchisonii Boiss. 1884SS05
‘Agrostis’ albaV72
P. alpigenaO88
|--P. a. ssp. alpigenaO88
`--P. a. ssp. staintoniiO88
P. alpinaV72 [=P. anceps var. alpinaC06, P. caespitosa var. alpinaB78]
P. alsodesV72
P. anceps [incl. P. anceps var. elata, P. anceps var. foliosa non Festuca foliosa]C06
|--P. a. var. ancepsC06
|--P. a. var. condensata Cheeseman 1906C06
|--P. a. var. debilisA27
|--P. a. var. densifloraA27
`--P. a. var. gracilis Cheeseman 1906C06
P. arcticaH44
P. arnoldiiO88
P. astoni Petrie 1906C06
P. attenuata Trin. 1835SS05
P. australis Br. 1810G52 (see below for synonymy)
|--P. a. var. australisC06
|--P. ‘caespitosa’ var. latifoliaB78
`--P. ‘caespitosa’ var. leioclada Hackel in Cheeseman 1906C06
P. autumnalisV72
P. bonariensisS06
P. brevifoliaJ23
P. breviglumisC06
P. bulbosa Linnaeus 1753PL04
|--P. b. var. bulbosaO88
`--P. b. var. viviparaO88
P. caesiaD60
‘Dissanthelium’ californicumH93
P. calliopsisO88
P. celsaW91
P. chathamica Petrie 1902C06
P. cheesemanii Hackel 1903C06
P. ciliarisC55b
P. clelandiiB00
P. colensoiC06
|--P. c. var. colensoiC06
`--P. c. var. intermedia Cheeseman 1906C06
P. cookiiSBG97
P. dipsacea Petrie 1894C06
P. drummondiana Nees 1843G52 [incl. P. brizochloa Muell. 1855B78, P. cognataG52, P. nodosaG52]
P. eleanoraeO88
P. ensiformisB00
P. eragrostisC55a
P. exiguaC06
P. falconeriO88
P. fawcettiaeB00
P. flabellataRJ11 [incl. Dactylis caespitosaC06]
P. foliosaH66 [=Festuca foliosaC06]
P. fuegianaD03
P. grisebachii Fries 1905S06
P. gunniiB00
P. hamiltoni Kirk 1895C06
P. hiemataB00
P. himalayanaO88
P. hirtiglumisO88
P. holciformisS06
P. homomallaB78
P. hookeriB00
P. huecuK15
P. imbecillaC06 [=Eragrostis imbecillaC06; incl. P. sprengeliiB78]
|--P. i. var. imbecillaC06
`--P. i. var. matthewsii (Petrie) Hackel in Cheeseman 1906C06 (see below for synonymy)
P. imperialisO88
P. inconspicua Veldkamp in Royen 1979GR98
P. incrassata Petrie 1902C06
P. interior [=P. nemoralis var. interior]V72
P. kanaii Rajbh. 1988SS05
P. kelloggiiH93
P. kirkii [incl. P. purpurea Kirk 1877 (n. n.)]C06
|--P. k. var. kirkiiC06
|--P. k. var. collinsii Hackel in Cheeseman 1906 [=P. collinsii Kirk ex Petrie 1896 (n. n.)]C06
`--P. k. var. mackayi (Buchanan) Hackel in Cheeseman 1906C06
P. labillardieriB00
P. langtangensisO88
P. languidaV72
P. lanuginosaS06
P. lepida Muell. 1873G52
P. ligularisRJ11
P. lilloiK15
P. lindsayiC06
P. litorosa Cheeseman 1906 [=Festuca scoparia non Poa scoparia]C06
P. ludensO88
P. maiaW91
P. maniototo Petrie 1890C06
P. maroccanaGR98
P. maxwelli Benth. 1878G52
P. morrisiiB00
P. mulalensisS06
P. myriantha Hackel in Stuckert 1906S06
P. novae-zealandiae Hack. 1903C06
|--P. n. var. novae-zealandiaeC06
`--P. n. var. subvestita Hack. 1903C06
P. pagophilaSS05
P. paludigenaV72
P. × perinconspicua Scholz in Greuter & Raus 1998 (see below for synonymy)GR98
P. poaeformis (Labill.) Druce 1917 [=Arundo poaeformis; incl. P. australis var. billardieri]G52
P. polycoleaO88
P. polyphylla Hack. 1903C06
P. poophagorumO88
P. pusilla Berggr. 1877 [incl. P. anceps var. minima]C06
P. pygmaeaC06
P. queenslandicaB00
P. quinquefidaJ23
P. ramosissimaC06
P. rodwayiB00
P. saltuensisV72
P. saxicolaMB08
P. scaberulaD03
P. sclerophylla Berggr. 1877 [incl. P. albida]C06
P. seticulmis Petrie 1902C06
P. sieberianaB00
P. sikkimensisO88
P. stapfianaO88
P. suksdorfiiH93
P. sylvestrisV72
P. teneraB00 [=P. caespitosa var. teneraB78; incl. P. effusaB78]
P. unifloraA27
P. wheeleriH93
Poa L. 1753 [incl. Anthochloa Nees & Meyen 1834, Aphanelytrum (Hack.) Hack. 1902, Austrofestuca (Tzvelev) Alexeev 1976, Dissanthelium Trin. 1836, Eremopoa Roshev. 1934, Libyella Pamp. 1925, Lindbergella Bor 1969, Neuropoa Clayton 1985, Oreopoa Scholz & Parolly 2004, Parodiochloa Hubb. 1981, Tovarochloa Macfarl. & But 1982, Tzvelevia Alexeev 1985]K15
Poa australis Br. 1810G52 [=P. caespitosa var. australisB78; incl. P. caespitosa var. affinisB78, G52, P. caespitosaG52, P. laevis var. filifoliaC06, P. implexaB78, P. australis var. laevisC06, G52, P. caespitosa var. laevisB78, P. caespitosa var. plebeiaB78, G52, P. porphyrocladosB78, P. caespitosa var. serpentumB78, G52, P. sieberianaB78]
Poa imbecilla var. matthewsii (Petrie) Hackel in Cheeseman 1906C06 [=P. matthewsii Petrie 1902C06; incl. P. anceps var. breviculmisA27, C06]
Poa × perinconspicua Scholz in Greuter & Raus 1998 [P. maroccana × P. infirma; =P. × inconspicua Scholz 1995 non Veldkamp in Royen 1979]GR98
*Type species of generic name indicated
References
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