Ruppiaceae

Taxonomy

Family name: Ruppiaceae Horan.

Synonym(s): [none]

Common name(s): ditch-grass family

*Number of genera/species: 1/9

List of genera records in GRIN-Global

Disseminule

fruit, sometimes with only endocarpendocarp:
the inner layer of the pericarp, if divided into layers
persistent

Description

Fruit indehiscentindehiscent:
not opening on its own, as in a fruit
, drupedrupe:
(indehiscent drupe) a fleshy, indehiscent fruit with one more hard pits enclosing seeds, derived from single, superior, simple or compound ovary; (dehiscent drupe) a fruit with a dry or fibrous to fleshy or leathery outer husk that early to tardily breaks apart (or opens), exposing one or more nutlike pits enclosing the seeds
, simple or aggregateaggregate:
fruit formed from a single flower with carpels several and distinct
, 1.3–4 mm long, ovoidovoid:
3D shape—ovate
, flask-shapedflask-shaped:
3D shape—generally circular in cross-section, broadest at or below the middle, approximately globose below that and constricted above to a relatively narrow neck
, or cylindricalcylindrical:
3D shape—a cylinder, with parallel sides and a circular cross-section; tubular or rod-shaped
, tereteterete:
approximately circular in cross section; width and thickness approximately equal
in transection, beakedbeak:
a usually firm, terminal appendage, sometimes tapered
(persistent stylestyle:
in a flower, the narrow and elongated part of the pistil between the stigma and the ovary; sometimes persisting in fruit
), often stalked, one-seeded. If an aggregateaggregate:
fruit formed from a single flower with carpels several and distinct
, then they resemble an umbel. Pericarppericarp:
fruit wall or fruit coat
green or brown, chartaceouschartaceous:
papery, papyraceous
or spongyspongy:
soft, light, discontinuous but cohesive, and somewhat resilient
, dulldull:
reflecting only a low proportion of incident light, with no apparent sheen
, smooth, often decaying. Endocarpendocarp:
the inner layer of the pericarp, if divided into layers
persistent and sometimes with a longitudinallongitudinal:
of or relating to length or the lengthwise dimension
operculum ridge.

Seed 1–4 mm long, attached to endocarpendocarp:
the inner layer of the pericarp, if divided into layers
.

Embryo well developed, straight or curvedcurved:
(of embryo) linear embryo is curved into an arch or horseshoe with the ends far apart
, fills seed coat, with an enlarged hypocotylhypocotyl:
portion of the embryonic axis below the cotyledons and above the radicle
, terminal cotyledoncotyledon:
a primary leaf of the embryo
, and laterallateral:
(of embryo) embryo lies along the side of the seed, generally towards one end; of, at, or from the side; in grasses, can refer to the sides adjacent to the dorsal and ventral sides
plumule.

Endosperm absent.

Identification features

Fruit
Type	drupedrupe: (indehiscent drupe) a fleshy, indehiscent fruit with one more hard pits enclosing seeds, derived from single, superior, simple or compound ovary; (dehiscent drupe) a fruit with a dry or fibrous to fleshy or leathery outer husk that early to tardily breaks apart (or opens), exposing one or more nutlike pits enclosing the seeds
Size range	1.3–4 mm long
Shape(s)	ovoidovoid: 3D shape—ovate , flask-shapedflask-shaped: 3D shape—generally circular in cross-section, broadest at or below the middle, approximately globose below that and constricted above to a relatively narrow neck , cylindricalcylindrical: 3D shape—a cylinder, with parallel sides and a circular cross-section; tubular or rod-shaped
Texture	chartaceouschartaceous: papery, papyraceous , spongyspongy: soft, light, discontinuous but cohesive, and somewhat resilient
Surface relief	smooth
Color(s)	green, brown
Unique features	Chartaceouschartaceous: papery, papyraceous or spongyspongy: soft, light, discontinuous but cohesive, and somewhat resilient , green or brown beakedbeak: a usually firm, terminal appendage, sometimes tapered drupes, often outer layers of the pericarps decay leaving only endocarps, which sometimes bear longitudinallongitudinal: of or relating to length or the lengthwise dimension operculum ridges.
Seed
Size range	1–4 mm long
Other
Embryo	well developed, straight or curvedcurved: (of embryo) linear embryo is curved into an arch or horseshoe with the ends far apart , fills seed coat, with an enlarged hypocotylhypocotyl: portion of the embryonic axis below the cotyledons and above the radicle , terminal cotyledoncotyledon: a primary leaf of the embryo , and laterallateral: (of embryo) embryo lies along the side of the seed, generally towards one end; of, at, or from the side; in grasses, can refer to the sides adjacent to the dorsal and ventral sides plumule
Nutritive tissue	endosperm absent

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; Bobrov and Romanov 2019Bobrov and Romanov 2019:
Bobrov AVFCH and Romanov MS. 2019. Morphogenesis of fruits and types of fruit of angiosperms. Botany Letters 166 (3): 366-399. https://doi.org/10.1080/23818107.2019.1663448; Cronquist 1981Cronquist 1981:
Cronquist A. 1981. An integrated system of classification of flowering plants. Columbia University Press, New York. 1261 pp.; 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 Australia 2021+Flora of Australia 2021+:
Flora of Australia. Australian Biological Resources Study, Canberra. Accessed January 2021–March 2024. URL: http://www.ausflora.org.au; 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.; Martin and Barkley 1961Martin and Barkley 1961:
Martin AC and Barkely WD. 1961. Seed Identification Manual. Universisty of California Press, Berkeley and Los Angeles, CA, USA. 220 pp.; 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.