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 an acheneachene:
a dry, indehiscent, one-seeded fruit, with seed attached to pericarp at a single point, derived from a single, superior, simple or compound, one-loculed ovary
, utricleutricle:
a small, indehiscent, dry fruit with a thin wall (bladderlike) that is loose and free from the seed, derived from a single, superior, simple ovary
, or 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
, 1.5–5 mm long, globoseglobose:
3D shape—more or less spherical
to ovoidovoid:
3D shape—ovate
, beakedbeak:
a usually firm, terminal appendage, sometimes tapered
, sometimes enclosed in fleshy bractbract:
a leaf-like or scale-like plant part, located just below a fruit (especially in grasses), flower, flower stalk, or an inflorescence
(Thalassodendron), with one seed. In all genera, fruits are aggregates, but with frequent abortion of one or both carpels fruit may appear as simple (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 fleshy. Genera identifiable based on fruit traits, see below.

Fruit traits by genus

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

Cymodocea: Fruits are semicircular to ellipsoidalellipsoid:
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 pericarps.

Halodule: Fruits are ovoid or somewhat compressedcompressed:
flattened; in grasses, used to denote compression (not necessarily flattened) either laterally or dorsiventrally
with stony pericarps.

Syringodium: Fleshy exocarps are 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. Endocarps are obliquely ellipsoidellipsoid:
3D shape—elliptic
or obovoidobovoid:
3D shape—obovate
, quadrangularquadrangular:
2D shape—four-sided, as in a square or rectangle
in transection, 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: Fruits enclosed by a fleshy bractbract:
a leaf-like or scale-like plant part, located just below a fruit (especially in grasses), flower, flower stalk, or an inflorescence
and germinate on mother plant but lack the lobes present in Amphibolus.

Seeds 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 transection, 2–10 mm long. Seeds germinate on parent plant in Amphibolis and Thalassodendron. In the other genera, seed coat is thick 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.

Endosperm 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	acheneachene: a dry, indehiscent, one-seeded fruit, with seed attached to pericarp at a single point, derived from a single, superior, simple or compound, one-loculed ovary , utricleutricle: a small, indehiscent, dry fruit with a thin wall (bladderlike) that is loose and free from the seed, derived from a single, superior, simple ovary , 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	1.5–50 mm long
Shape(s)	ovoidovoid: 3D shape—ovate , globoseglobose: 3D shape—more or less spherical , ellipsoidellipsoid: 3D shape—elliptic , hemisphericalhemispherical: 2D shape—shaped like half a sphere
Texture	crustaceouscrustaceous: texture—thin, dry, indurate, and brittle , leatheryleathery: texture—moderately thick, tough, and very pliable , indurateindurate: texture—hardened or stony; yielding under strong pressure; not deformable without internal structural disruption
Surface relief	smooth or ridgedridged: surface relief—raised, thick ridges, sharp edged or rounded, usually in a series that may cover the entire surface
Color(s)	black, brown
Unique features	Indehiscentindehiscent: 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	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 , 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 thick, 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 tissue	endosperm 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+Nooteboom et al. 2021+:
Nooteboom HP, de Wilde WJJO, Stevens PF, Coode MJE, and Saw LG. 2021+ Flora Malesiana Online. Accessed January 2021–March 2024. URL: https://portal.cybertaxonomy.org/flora-malesiana/; 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; 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.; 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. 111-133). 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): 201-217. https://doi.org/10.11646/phytotaxa.261.3.1, which may differ from the number of genera in GRIN-Global.