Poaceae

Taxonomy

Family name: Poaceae Barnhart

Synonym(s): Aegilopaceae Martinov; Agrostidaceae Bercht. & J. Presl; Alopecuraceae Martinov; Andropogonaceae Martinov; Anomochloaceae Nakai; Anthoxanthaceae Link; Arundinaceae Döll; Arundinellaceae Herter; Asperellaceae Link; Avenaceae Martinov; Bambusaceae Bercht. & J. Presl; Cenchrinaceae Link; Chaeturaceae Link; Chloridaceae Bercht. & J. Presl; Coleanthaceae Pfeiff.; Cynodontaceae Link; Cynosuraceae Link; Echinariaceae Link; Ehrhartaceae Link; Eragrostidaceae Herter; Festucaceae Spreng.; Glyceriaceae Link; Gramineae Juss., nom. cons.; Hordeaceae Bercht. & J. Presl; Lepturaceae Herter; Miliaceae Link; Ophiuraceae Link ex Pfeiff., nom. inval.; Oryzaceae Bercht. & J. Presl; Panicaceae Bercht. & J. Presl; Pappophoraceae Herter; Parianaceae Nakai; Paspalaceae Link; Phalaridaceae Link; Pharaceae Herter; Sporobolaceae Herter, nom. inval.; Stipaceae Bercht. & J. Presl; Streptochaetaceae Nakai; Triticaceae Link; Zoysiaceae Link

Common name(s): grass family

*Number of genera/species: 780/12,000

List of Genera in GRIN-Global

Key to the grass genera of the world

Disseminule

Spikelet, floretfloret:
the unit of a grass spikelet consisting of a flower or caryopsis, with lemma and palea
, fruit, or seed

Description

Fruit indehiscentindehiscent:
not opening on its own, as in a fruit
, usually caryopsiscaryopsis:
a small, indehiscent, dry, fruit with a thin wall surrounding and more or less fused to a single seed
, sometimes utricleutricle:
a small, indehiscent, dry fruit with a thin wall (bladderlike) that is loose and free from the seed
(Crypsis, Sporobolus, Eleusine), rarely acheneachene:
a dry, indehiscent, one-seeded fruit, with seed attached to pericarp at a single point
, nutnut:
a fairly large, indehiscent, dry fruit with a thick and bony wall surrounding a single seed
, or berryberry:
an indehiscent, fleshy fruit with one or a few to many seeds. The flesh may be homogenous throughout. Or, if the outer part is hard, firm, or leathery, referred to as an hesperidium. Septa are present in some, and the seeds may be arillate or with a fleshy testa.
(Melocanna baccifera), 0.3–40 mm long, globoseglobose:
3D shape—more or less spherical
to falcatefalcate:
shaped like a scythe or sickle
, roundround:
2D shape—orbiculate; circular
, angledangled:
2D shape—having sides that meet at acute or obtuse angles  
, or compressedcompressed:
flattened; in grasses, used to denote compression (not necessarily flattened) either laterally or dorsiventrally
in transectiontransection:
a cross section; representing a plane made by cutting across an organ at a right angle to its length
, sometimes sulcatesulcate:
surface relief—having one or more elongate, relatively narrow and shallow depressions or grooves
, sometimes beakedbeaked:
a usually firm, terminal appendage, sometimes tapered
, usually with persistent accessory tissue including glume(s), lemmalemma:
in grasses, the lower of the two bracts subtending the flower or caryopsis (compare palea)
, paleapalea:
in grasses, the uppermost bract enclosing the flower or caryopsis (compare lemma)
, and/or stylesstyles:
in a flower, the narrow and elongated part of the pistil between the stigma and the ovary; sometimes persisting in fruit
, one seeded. Pericarppericarp:
fruit wall or fruit coat
usually fused to seed coat, black, brown, purple, yellow, red, or white, shinyshiny:
uniformly reflecting a high proportion of incident light at all angles
or dulldull:
reflecting only a low proportion of incident light, with no apparent sheen
, membranousmembranous:
texture—extremely thin, pliable, and fairly tough
, fleshyfleshy:
texture—fairly firm and dense, juicy or at least moist, and easily cut
, leatheryleathery:
texture—moderately thick, tough, and very pliable
, or crustaceouscrustaceous:
texture—thin, dry, indurate, and brittle
, smooth, groovedgrooved:
surface relief—linear depressions that may be single or form a series of grooves over the surface
, ribbedribbed:
surface relief—wide, prominent, linear ridges that are generally rounded and longitudinally situated on the surface
, striatestriate:
surface relief—having fine, parallel lines, grooves or ridges
, wrinkledwrinkled:
surface relief—shallow, irregular folds and furrows covering the surface; appearing overall though crumpled and then spread out
, or spinyspiny:
having slender, stiff, sharp projections oriented in the general plane of the structure
, sometimes pubescentpubescent:
surface relief—bearing hairs
.

Seed oblongoblong:
2D shape—much longer than broad with nearly parallel sides, corners are rounded
, tereteterete:
approximately circular in cross section; width and thickness approximately equal
, turtle-shaped, angularangular:
2D shape—having sides that meet at acute or obtuse angles  
, or compressedcompressed:
flattened; in grasses, used to denote compression (not necessarily flattened) either laterally or dorsiventrally
in transectiontransection:
a cross section; representing a plane made by cutting across an organ at a right angle to its length
, 0.3–40 mm long. Hilumhilum:
on seeds, the scar indicating where the funiculus was attached; on grass caryopses, the scar visible on the outer caryopsis surface revealing where the seed is attached on the inner fruit wall surface; or in Asteraceae cypselae, the scar visible on the pericarp revealing where the fruit was attached to the receptacle
present, punctatepunctate:
surface relief—dotted with pits or with translucent, sunken glands or with colored dots, similar to pitted
or larger than punctatepunctate:
surface relief—dotted with pits or with translucent, sunken glands or with colored dots, similar to pitted
, often linearlinear:
(shape) long, narrow, and uniform in width; (of embryo) embryo is straight and much longer than wide
. Seed coat brown, thinthin:
having or being of relatively little depth
, unsmooth.

Embryo well developed, linearlinear:
(shape) long, narrow, and uniform in width; (of embryo) embryo is straight and much longer than wide
, straight or curvedcurved:
(of embryo) linear embryo is curved into an arch or horseshoe with the ends far apart
, completely or partially filling seed coat, obliqueoblique:
in a slanting direction or position, neither horizontal nor vertical
to the seed length, positioned abaxially, scutellumscutellum:
the single, relatively large cotyledon of a grass embryo
present and appressedappressed:
pressed close to or lying flat against something, as in hairs on grass bract
to endospermendosperm:
nutritive starch- and oil-containing tissue present in many seeds
. Endospermendosperm:
nutritive starch- and oil-containing tissue present in many seeds
usually copious (lacking in Melocanna), transparent, fleshyfleshy:
texture—fairly firm and dense, juicy or at least moist, and easily cut
, mealymealy:
loose, dry, and disintegrating in finely granular pieces like meal or flour
, hard, or watery in a few genera.

Habitat and crop association

Noxious Weeds: USA Federal Noxious Weed List, all are terrestrial, Avena sterilis (including Avena ludoviciana Durieu) Linnaeus; Chrysopogon aciculatus (Retzius) Trinius; Digitaria abyssinica (Hochstetter ex A. Richard) Stapf; Digitaria velutina (Forsskal) Palisot de Beauvois; Imperata brasiliensis Trinius; Imperata cylindrica (Linnaeus) Palisot de Beauvois; Ischaemum rugosum Salisbury; Leptochloa chinensis (Linnaeus) Nees; Nassella trichotoma (Nees) Hackel ex Arechavaleta; Oryza longistaminata A. Chevalier & Roehrich; Oryza punctata Kotschy ex Steudel; Oryza rufipogon Griffith; Paspalum scrobiculatum Linnaeus; Pennisetum clandestinum Hochstetter ex Chiovenda; Pennisetum macrourum Trinius; Pennisetum pedicellatum Trinius; Pennisetum polystachion (Linnaeus) Schultes; Rottboellia cochinchinensis (Lour.) W. Clayton; Saccharum spontaneum Linnaeus; Setaria pumila subsp. pallidefusca (Schumach.) B.K. Simon; Urochloa panicoides Beauvois. Poaceae Key to Federal Noxious Weeds.

Identification features

Fruit
Type	usually caryopsiscaryopsis: a small, indehiscent, dry, fruit with a thin wall surrounding and more or less fused to a single seed , sometimes utricleutricle: a small, indehiscent, dry fruit with a thin wall (bladderlike) that is loose and free from the seed , rarely acheneachene: a dry, indehiscent, one-seeded fruit, with seed attached to pericarp at a single point , nutnut: a fairly large, indehiscent, dry fruit with a thick and bony wall surrounding a single seed , or berry
Size range	0.3–40 mm long
Shape(s)	oblong, linearlinear: (shape) long, narrow, and uniform in width; (of embryo) embryo is straight and much longer than wide , ellipsoidellipsoid: 3D shape—elliptic , ovoidovoid: 3D shape—ovate , cylindricalcylindrical: 3D shape—a cylinder, with parallel sides and a circular cross-section; tubular or rod-shaped , teardrop-shapedteardrop-shaped: 2D shape—widest point is toward one end of the fruit, the other end tapers sharply to a pointed end , fusiformfusiform: spindle-shaped; broadest at the middle and tapering at both ends , globoseglobose: 3D shape—more or less spherical , lens-shapedlens-shaped: 2D shape—round and flattened with two curved (convex) surfaces , falcatefalcate: shaped like a scythe or sickle , reniformreniform: 2D or 3D shape—kidney-shaped , trigonous
Texture	membranous, fleshyfleshy: texture—fairly firm and dense, juicy or at least moist, and easily cut , leatheryleathery: texture—moderately thick, tough, and very pliable , crustaceous
Surface relief	smooth, ribbedribbed: surface relief—wide, prominent, linear ridges that are generally rounded and longitudinally situated on the surface , striatestriate: surface relief—having fine, parallel lines, grooves or ridges , groovedgrooved: surface relief—linear depressions that may be single or form a series of grooves over the surface , wrinkledwrinkled: surface relief—shallow, irregular folds and furrows covering the surface; appearing overall though crumpled and then spread out , spiny
Color(s)	red, brown, white, black, yellow, purple
Unique features	Usually one-seeded caryopsescaryopses: a small, indehiscent, dry, fruit with a thin wall surrounding and more or less fused to a single seed (pericarp fused to seed coat) with persistent perianthperianth: collective term for calyx and corolla of a flower or bracts and often dispersed in a spikeletspikelet: basic unit of the grass inflorescence, commonly consisting of a pair of glumes and one to many florets .
Seed
Size range	0.3–40 mm long
Shape(s)	oblongoblong: 2D shape—much longer than broad with nearly parallel sides, corners are rounded
Surface relief	unsmooth
Color(s)	brown
Unique features	Seeds tightly fused to pericarppericarp: fruit wall or fruit coat with scutellumscutellum: the single, relatively large cotyledon of a grass embryo present.
Other
Embryo	well developed, linearlinear: (shape) long, narrow, and uniform in width; (of embryo) embryo is straight and much longer than wide , straight or curvedcurved: (of embryo) linear embryo is curved into an arch or horseshoe with the ends far apart , completely or partially filling seed coat, obliqueoblique: in a slanting direction or position, neither horizontal nor vertical to the seed length, positioned abaxially, scutellumscutellum: the single, relatively large cotyledon of a grass embryo present
Nutritive tissuenutritive tissue: tissue within the seeds that nourishes the developing embryo; such as endosperm, perisperm, or chalazosperm in angiosperms; megagametophyte in gymnosperms	usually copious (lacking in Melocanna), transparent, fleshyfleshy: texture—fairly firm and dense, juicy or at least moist, and easily cut , mealymealy: loose, dry, and disintegrating in finely granular pieces like meal or flour , hard, or watery in a few genera

Distribution

Worldwide.

Distribution map courtesy of Angiosperm Phylogeny Website.

References

Baskin and Baskin 2021Baskin and Baskin 2021:
Baskin C and Baskin J. 2021. Relationship of the lateral embryo (in grasses) to other monocot embryos: A status up-grade. Seed Science Research 31 (3): 199-210. doi:10.1017/S0960258521000209; Dahlgren et al. 1985Dahlgren et al. 1985:
Dahlgren RMT, Clifford HT, and Yeo PF. 1985. The families of the monocotyledons: structure, evolution, and taxonomy. Springer-Verlag, Berlin. 520 pp.; Flora of North America Editorial Committee 1993+Flora of North America Editorial Committee 1993+:
Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico [Online]. 22+ vols. Flora of North America Association, New York and Oxford. Accessed January-December 2021. URL: http://beta.floranorthamerica.org.; Kirkbride et al. 2006Kirkbride et al. 2006:
Kirkbride JH, Jr, Gunn CR, and Dallwitz MJ. 2006. Family guide for fruits and seeds, vers. 1.0. Accessed September 2020ndash;January 2022. URL: https://nt.ars-grin.gov/seedsfruits/keys/frsdfam/index.cfm .; Kubitzki et al. 1990+Kubitzki et al. 1990+:
Kubitzki K et al., eds. 1990+. The families and genera of vascular plants. 7+ vols. Berlin etc.; Stevenson and Loconte 1995Stevenson and Loconte 1995:
Stevenson DW and Loconte H. 1995. A cladistic analysis of monocot families. In: Rudall PJ, Cribb PJ, Cutler DF, and Humphries CJ, eds. Monocotyledons: Systematics and Evolution. Royal Botanic Gardens, Kew.; Watson and Dallwitz 1992+Watson and Dallwitz 1992+:
Watson L and Dallwitz MJ. 1992+. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 6th Accessed September 2020-September 2022. URL: delta-intkey.com; Zhengyi et al. 2004+Zhengyi et al. 2004+:
Zhengyi W, Raven PH, and Deyuan H. 2004+. Flora of China [online]. 25 vols. Science Press, Beijing China amp; Missouri Botanical Garden, St. Louis USA. Accessed January-December 2021. http://flora.huh.harvard.edu/china/

*The number of genera and species is based on Christenhusz and Byng 2016Christenhusz and Byng 2016:
Christenhusz MJM and Byng JW. 2016. The number of known plant species in the world and its annual increase. Phytotaxa 261 (3): 201ndash;217. https://doi.org/10.11646/phytotaxa.261.3.1, which may differ from the number of genera in GRIN-Global.