Juncaceae

Taxonomy

Family name: Juncaceae A.L. Jussieu

Synonym(s): [none]

Common name(s): rush family

*Number of genera/species: 8/464

List of genera records in GRIN-Global

Disseminule

fruit or seed

Description

Fruit a loculicidalloculicidal:
type of capsular dehiscence, opening longitudinally through the locules (compare septicidal)
capsulecapsule:
a dry, dehiscent fruit derived from a compound ovary
, rarely circumscissilecircumscissile:
(~pyxis); type of capsular dehiscence, opens by a lid (splitting transversely)
(Distichia, Patosia) or indehiscentindehiscent:
not opening on its own, as in a fruit
(Oxychloe), 2–9 mm long, globoseglobose:
3D shape—more or less spherical
to trigonoustrigonous:
3D shape—having three faces that meet at distinct angles; triangular in outline
, tereteterete:
approximately circular in cross section; width and thickness approximately equal
or angledangular:
2D shape—having sides that meet at acute or obtuse angles  
in transection, sometimes beakedbeak:
a usually firm, terminal appendage, sometimes tapered
or with stylar remnantsstyle base:
remnant of a style
, with many seeds except three-seeded in Luzula. Pericarppericarp:
fruit wall or fruit coat
black, brown, purple, red, or orange, 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
, chartaceouschartaceous:
papery, papyraceous
or indurateindurate:
texture—hardened or stony; yielding under strong pressure; not deformable without internal structural disruption
, smooth.

Seeds globoseglobose:
3D shape—more or less spherical
to irregular, tereteterete:
approximately circular in cross section; width and thickness approximately equal
in transection, 0.3–4 mm long, sometimes each with winglike beak or caudatecaudate:
tapering to a long, tail-like appendage
appendage, often with conspicuous raphaeraphe:
a ridge or seam on the seed coat, formed by the portion of the funiculus united to the ovule wall in longitudinally curved ovules
. Seeds in Luzula shinyshiny:
uniformly reflecting a high proportion of incident light at all angles
and with basalbasal:
at or pertaining to the point of attachment; (of embryo) embryo occupies one end of the seed
or apicalapical:
at or pertaining to the end of the seed or fruit distal from its point of attachment (i.e., base)
elaiosomes. Seed coat brown, yellow, red, or white, dulldull:
reflecting only a low proportion of incident light, with no apparent sheen
or shinyshiny:
uniformly reflecting a high proportion of incident light at all angles
, membranousmembranous:
texture—extremely thin, pliable, and fairly tough
, loose or tight, smooth, reticulatereticulate:
surface relief—netted, raised walls or concave grooves forming a net-like surface pattern with flat, concave, or convex interspaces
, wrinkledwrinkled:
surface relief—shallow, irregular folds and furrows covering the surface; appearing overall though crumpled and then spread out
, or striatestriate:
surface relief—having fine, parallel lines, grooves or ridges
. In some species of Juncus and Luzula elegans, seed coat may be mucilaginousmucilaginous:
resembling mucilage; moist and sticky
when wet.

Embryo rudimentaryrudimentary:
(of embryo) embryo is small and fills less than a quarter of the seed and can be variable in shapes, such as linear, spatulate, or oval
and minute or well developed and larger, linearlinear:
(shape) long, narrow, and uniform in width; (of embryo) embryo is straight and much longer than wide
or broad, straight, axileaxile:
on or of the axis
and centric or peripheralperipheral:
(of embryo) embryo is curved around the outer edge of the seed, near the seed coat
.

Endosperm copious, fleshy, firm.

Habitat and crop association

Weedy in wetlands, shallow waters, and fields, spreading by rhizome propagation.

Aquarium & Pond Plants of the World tool includes descriptions and images of Juncus species, which may be encountered.

Identification features

Fruit
Type	capsulecapsule: a dry, dehiscent fruit derived from a compound ovary , rarely a nutletnutlet: ˜achene
Size range	2–9 mm long
Shape(s)	globoseglobose: 3D shape—more or less spherical , oblongoblong: 2D shape—much longer than broad with nearly parallel sides, corners are rounded , ellipsoidellipsoid: 3D shape—elliptic , trigonoustrigonous: 3D shape—having three faces that meet at distinct angles; triangular in outline , conicalconical: 3D shape—cone-shaped, with the point of attachment at the broad end
Texture	chartaceouschartaceous: papery, papyraceous , indurateindurate: texture—hardened or stony; yielding under strong pressure; not deformable without internal structural disruption
Surface relief	smooth
Color(s)	brown, purple, red, orange, black
Unique features	Small, smooth capsulescapsule: a dry, dehiscent fruit derived from a compound ovary often with many beakedbeak: a usually firm, terminal appendage, sometimes tapered or caudatecaudate: tapering to a long, tail-like appendage appendaged seeds.
Seed
Size range	0.3–4 mm long
Shape(s)	polygonalpolygonal: angular , globoseglobose: 3D shape—more or less spherical , ovoidovoid: 3D shape—ovate , sectoroidsectoroid: 3D shape—a wedge-shaped slice taken from an ovoid or globose structure (2D shape, sector-shaped) , ellipsoidellipsoid: 3D shape—elliptic , fusiformfusiform: spindle-shaped; broadest at the middle and tapering at both ends , irregular, oblongoblong: 2D shape—much longer than broad with nearly parallel sides, corners are rounded
Surface relief	smooth, reticulatereticulate: surface relief—netted, raised walls or concave grooves forming a net-like surface pattern with flat, concave, or convex interspaces , wrinkledwrinkled: surface relief—shallow, irregular folds and furrows covering the surface; appearing overall though crumpled and then spread out , striatestriate: surface relief—having fine, parallel lines, grooves or ridges
Color(s)	brown, red, yellow, white
Unique features	Seeds often beakedbeak: a usually firm, terminal appendage, sometimes tapered , with caudatecaudate: tapering to a long, tail-like appendage appendage, and/or with conspicuous rapheraphe: a ridge or seam on the seed coat, formed by the portion of the funiculus united to the ovule wall in longitudinally curved ovules . Seed coats may be mucilaginousmucilaginous: resembling mucilage; moist and sticky .
Other
Embryo	rudimentaryrudimentary: (of embryo) embryo is small and fills less than a quarter of the seed and can be variable in shapes, such as linear, spatulate, or oval and minute or well developed and larger, linearlinear: (shape) long, narrow, and uniform in width; (of embryo) embryo is straight and much longer than wide or broad, straight, axileaxile: on or of the axis and centric or peripheralperipheral: (of embryo) embryo is curved around the outer edge of the seed, near the seed coat
Nutritive tissue	endosperm copious, fleshy, firm

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-March 2024. 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 2020-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 & Missouri Botanical Garden, St. Louis USA. Accessed January–March 2024. 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): 201-217. https://doi.org/10.11646/phytotaxa.261.3.1, which may differ from the number of genera in GRIN-Global.