Cymodoceaceae

Taxonomy

Family name: Cymodoceaceae Vines

Synonym(s): [none]

Common name(s): manatee-grass family

*Number of genera/species: 5/17

List of genera records in GRIN-Global

Disseminule

fruit

Description

Fruit indehiscent, acheneachene:
a dry, indehiscent, one-seeded fruit, with seed attached to pericarp at a single point
, utricleutricle:
a small, indehiscent, dry fruit with a thin wall (bladderlike) that is loose and free from the seed
, or indehiscentindehiscent:
not opening on its own, as in a fruit
, drupedrupe:
(indehiscent drupe) a fleshy, indehiscent fruit with one more hard pits enclosing seeds; (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
, 1.5–5 mm long, globoseglobose:
3D shape—more or less spherical
to ovoidovoid:
3D shape—ovate
, beakedbeaked:
a usually firm, terminal appendage, sometimes tapered
, sometimes enclosed in fleshyfleshy:
texture—fairly firm and dense, juicy or at least moist, and easily cut
bractbract:
a leaf-like or scale-like plant part, located just below a fruit (especially in grasses), flower, flower stalk, or an inflorescence
(Thalassodendron), one seeded. In all genera, fruits are aggregateaggregate:
fruit formed from a single flower with carpels several and distinct
, but with frequent abortion of one or both carpels fruit may appear as simplesimple:
fruit formed from a single flower with one pistil, solitary carpel or several fused carpels
(Thalassodendron). Pericarppericarp:
fruit wall or fruit coat
black or brown, crustaceouscrustaceous:
texture—thin, dry, indurate, and brittle
, leatheryleathery:
texture—moderately thick, tough, and very pliable
, or stony, smooth or ridgedridged:
surface relief—raised, thick ridges, sharp edged or rounded, usually in a series that may cover the entire surface
, if mesocarpmesocarp:
the middle layer of the pericarp, if divided into layers
present then fleshyfleshy:
texture—fairly firm and dense, juicy or at least moist, and easily cut
. Genera identifiable based on fruit traits, see below.

Fruit traits by genus

Amphibolus: Fruit germinates almost immediately on the mother plant. The fruit base has four pectinate, spreading lobes (or bristles) that remain when seedling is released.

Cymodocea: Fruit semicircular to ellipsoidalellipsoidal:
3D shape—elliptic
, laterally compressedcompressed:
flattened; in grasses, used to denote compression (not necessarily flattened) either laterally or dorsiventrally
, with dorsaldorsal:
abaxial; the back of an organ; the side away from the axis (compare ventral)
ridges and stony pericarppericarp:
fruit wall or fruit coat
.

Halodule: Fruit ovoidovoid:
3D shape—ovate
or somewhat compressedcompressed:
flattened; in grasses, used to denote compression (not necessarily flattened) either laterally or dorsiventrally
with stony pericarppericarp:
fruit wall or fruit coat
.

Syringodium: Fleshyfleshy:
texture—fairly firm and dense, juicy or at least moist, and easily cut
exocarpexocarp:
outer layer of fruit wall or pericarp, if divided into layers; note here used synonymously with epicarp
is quickly shed and only the stony endocarpendocarp:
the inner layer of the pericarp, if divided into layers
remains in marine sediment, with differences in surface relief by species. Endocarpendocarp:
the inner layer of the pericarp, if divided into layers
is obliquely ellipsoidellipsoid:
3D shape—elliptic
or obovoidobovoid:
3D shape—obovate
, quadrangularquadrangular:
2D shape—four-sided, as in a square or rectangle
in transectiontransection:
a cross section; representing a plane made by cutting across an organ at a right angle to its length
, with median ridge and bifidbifid:
two-lobed or two-cleft (usually in reference to an apex)
beakbeak:
a usually firm, terminal appendage, sometimes tapered
.

Thalassodendron: Fruit enclosed by a fleshyfleshy:
texture—fairly firm and dense, juicy or at least moist, and easily cut
bractbract:
a leaf-like or scale-like plant part, located just below a fruit (especially in grasses), flower, flower stalk, or an inflorescence
and germinates on mother plant but lack lobes present in Amphibolus.

Seed straight, compressedcompressed:
flattened; in grasses, used to denote compression (not necessarily flattened) either laterally or dorsiventrally
or tereteterete:
approximately circular in cross section; width and thickness approximately equal
in transectiontransection:
a cross section; representing a plane made by cutting across an organ at a right angle to its length
, 2–10 mm long. Seed germinates on parent plant in Amphibolis and Thalassodendron. In the other genera, seed coat is thickthick:
having or being of relatively great depth
and hard, wrinkledwrinkled:
surface relief—shallow, irregular folds and furrows covering the surface; appearing overall though crumpled and then spread out
, reticulatereticulate:
surface relief—netted, raised walls or concave grooves forming a net-like surface pattern with flat, concave, or convex interspaces
, ribbedribbed:
surface relief—wide, prominent, linear ridges that are generally rounded and longitudinally situated on the surface
, or groovedgrooved:
surface relief—linear depressions that may be single or form a series of grooves over the surface
.

Embryo well developed, 2–3 mm long, macropodousmacropodous:
an embryo having an enlarged or elongated hypocotyl
, linearlinear:
(shape) long, narrow, and uniform in width; (of embryo) embryo is straight and much longer than wide
, curvedcurved:
(of embryo) linear embryo is curved into an arch or horseshoe with the ends far apart
, filling seed coat. Endospermendosperm:
nutritive starch- and oil-containing tissue present in many seeds
is absent instead the nutrients are stored in the large hypocotylhypocotyl:
portion of the embryonic axis below the cotyledons and above the radicle
.

Identification features

Fruit
Type	achene, utricleutricle: a small, indehiscent, dry fruit with a thin wall (bladderlike) that is loose and free from the seed , or indehiscentindehiscent: not opening on its own, as in a fruit drupe
Size range	1.5–50 mm long
Shape(s)	ovoid, globoseglobose: 3D shape—more or less spherical , ellipsoidellipsoid: 3D shape—elliptic , hemispherical
Texture	crustaceous, leatheryleathery: texture—moderately thick, tough, and very pliable , indurate
Surface relief	smooth or ridged
Color(s)	black, brown
Unique features	Indehiscent indehiscent: not opening on its own, as in a fruit one-seeded, beakedbeak: a usually firm, terminal appendage, sometimes tapered , fruits with stony pericarppericarp: fruit wall or fruit coat or endocarpendocarp: the inner layer of the pericarp, if divided into layers . Or viviparous.
Seed
Size range	2–10 mm long
Shape(s)	straight
Surface relief	wrinkled, reticulatereticulate: surface relief—netted, raised walls or concave grooves forming a net-like surface pattern with flat, concave, or convex interspaces , ribbedribbed: surface relief—wide, prominent, linear ridges that are generally rounded and longitudinally situated on the surface , groovedgrooved: surface relief—linear depressions that may be single or form a series of grooves over the surface .
Unique features	Seeds germinate on parent plant. Or, seeds with thickthick: having or being of relatively great depth , hard seed coats, which are wrinkledwrinkled: surface relief—shallow, irregular folds and furrows covering the surface; appearing overall though crumpled and then spread out , reticulatereticulate: surface relief—netted, raised walls or concave grooves forming a net-like surface pattern with flat, concave, or convex interspaces , ribbedribbed: surface relief—wide, prominent, linear ridges that are generally rounded and longitudinally situated on the surface , or groovedgrooved: surface relief—linear depressions that may be single or form a series of grooves over the surface , and with large, macropodousmacropodous: an embryo having an enlarged or elongated hypocotyl embryos.
Other
Embryo	well developed, 2–3 mm, macropodousmacropodous: an embryo having an enlarged or elongated hypocotyl , linearlinear: (shape) long, narrow, and uniform in width; (of embryo) embryo is straight and much longer than wide , curvedcurved: (of embryo) linear embryo is curved into an arch or horseshoe with the ends far apart , filling seed coat
Nutritive tissuenutritive tissue: tissue within the seeds that nourishes the developing embryo; such as endosperm, perisperm, or chalazosperm in angiosperms; megagametophyte in gymnosperms	endosperm endosperm: nutritive starch- and oil-containing tissue present in many seeds lacking

Distribution

Mainly tropical to subtropical oceans, occasionally occurring in warm-temperate areas.

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; Beentje 2002Beentje 2002:
Beentje HJ. 2002. Cymodoceaceae. In: Beentje HJ and Smith SAL, eds. Flora of Tropical East Africa. Vol 52b. AA Balkema, Rotterdam Netherlands. 10 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.; Nooteboom et al. 2021; Flora of Australia 2021+Flora of Australia 2021+:
Flora of Australia. Australian Biological Resources Study, Canberra. Accessed January-May 2021. URL: http://www.ausflora.org.au; 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.; Orth et al. 2006Orth et al. 2006:
Orth RJ, Harwell MC, and Inglis GJ. 2006. Ecology of seagrass seeds and seagrass dispersal processes. In: Larkum AWD, Orth RJ, and Duarte CM, eds. Seagrasses: biology, ecology and conservation (pp. 111ndash;133). Springer, Netherlands.; 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

*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.