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Common name: Posidonia Family.
Number of genera 1. Number of species 3.
Angiosperm. Liliopsida.
Disseminule a dehisced fruit, or a seed.
Fruits
Pistil(s) simple; 1; 1-pistillate. Fruit pericarpium; simple; camara (Spjut Fig. 14D), or drupe (not Spjut); without persistent central column; with styles(s); at apex; not within accessory organ(s); 1-seeded; 1-seeded; from 1–5 cm long; 1–2 cm long; 1-carpellate; not sulcate; in transection terete; apex not beaked; wall slightly fleshy; dehiscent. Dehiscent unit seed(s). Dehiscent irregularly; passively; and shedding seeds, or but retaining seed(s); without replum. Epicarp when mature brown (all shades), or black (up on drying); dull; durable; glabrous (without hairs); without armature; without wing(s); without apical respiratory hole. Mesocarp present; fleshy; composed of 1 unified layer; without lactiform cavity system. Endocarp present; not separating from exocarp; thin; not splitting into 1-seeded pyrenes; without operculum; without secretory cavities; without longitudinal ridges. Funiculus short; short without seed bearing hooks (retinacula); not persisting in fruit after seed shed.
Seeds
Aril absent. Seed larger than minute; 10 to less than 25 mm long; up to 20 mm long; elliptic, or lanceolate, or oblong; in transection terete; not bowl shaped; not nutlike; without winglike beak; without caudate appendage(s); at maturity without food reserves; without canavanine. Sarcotesta absent. Testa present, or absent; deciduous; without embryo surrounded and capped by viscid tissue; without markedly different marginal tissue; without fleshy or leathery layer over hard layer; tight; without crease or line separating cotyledons from hypocotyl-radicle; without notch along margin where cotyledons from hypocotyl-radicle tip approach each other; without glands; without bristles; glabrous; with wing(s), or without wings; 1-winged; with wing on one side (ventral side); with wing(s) solid; with solid wing(s) similar to testa; without collar; without operculum; colored; monochrome; brown (all shades) (ish); thin, or membranous; not becoming mucilaginous when wetted; surrounding embryo. Hilum punctate.
Embryo differentiated from food reserve; well developed; 1 per seed; completely filling testa (no food reserve); chamber lateral to wing; 1 times the length of food reserve; at one end of seed not extending into a depression or cup; straight; parallel to seed length; with cotyledons gradually connected to hypocotyl-radicle; without coleoptile; without coleorhiza; without simmondsin; without stomata; green; with 1 cotyledon. Cotyledons one and lateral with terminal plumule; not modified into scutellum; not circinately coiled. Hypocotyl-radicle well developed (listed as a macropodous embryo = prominent hypocotyl); straight; much thickened. Plumule well developed; composed of several seed-leaves (4); straight; terminal between 2 cotyledons.
Distribution
Old World. Mediterranean region Europe, Africa, southeastern Asia, and Australia.
Notes
Airy Shaw: "Indehiscent or the fleshy exocarp splitting from the base into 2–3 valves, whilst the thin endocarp splits shortly at apex, permitting the emergence of the plumule of the germinating seed. " Dahlgren et al.: "Fruit slightly fleshy, having a spongy pericarp, but dehisces to release the elongated seed".
Weed information
No USA noxious weeds.
Listed seeds
No ASOA or ISTA listed seeds.
Accepted genera
Posidonia K. D. Koenig, nom. cons.
References specific to this family
Cronquist page 1069. Hartog, C. den. 1970. The sea-grasses of the world. Verh. Kon. Ned. Akad. Wetensch., Afd. Natuurk. 59:1–275.
General references
Baillon, H.E. 1866–95. Histoire des plantes, 13 vols. Hachette and Co., Paris, Cronquist, A. 1981. An integrated system of classification of flowering plants, 1,262 p. Columbia University Press, New York, Dahlgren, R.M.T., H.T. Clifford and P.F. Yeo. 1985. The families of the monocotyledons, 520 pp. Springer-Verlag, Berlin, Goldberg, A. 1986 (dicots) and 1989 (monocots). Classification, evolution, and phylogeny of the familes of Dicotyledons. Smithsonian Contr. Bot. 58 for dicots (314 pp.) and 71 for monocots (74 pp.). [Goldberg's illustrations are reproduced from older publications and these should be consulted], Gunn, C.R., J.H. Wiersema, C.A. Ritchie, and J.H. Kirkbride, Jr. 1992 and amendments. Families and genera of Spermatophytes recognized by the Agricultural Research Service. Techn. Bull. U.S.D.A. 1796:1–500, Spjut, R.W. 1994. A systematic treatment of fruit types. Mem. New York Bot. Gard. 70:1–182.
Illustrations
Acceptable fruit and no seed illustration. Disseminule illustration(s): fruit, or embryo. Fruit illustration(s): Baillon [see Goldberg], Karen. Embryo illustration(s): Karen. Karen's plate number and taxon (taxa): 331: Posidonia australis Hook. f. (A-B).
• Fruit. 1 of 3. Posidonia australis Hook. f.: fruit with calyx. • Seed. 2 of 3. Posidonia australis Hook. f.: fruit. • Embryo. 3 of 3. Posidonia australis Hook. f.: embryo.
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘J.H. Kirkbride, Jr., C.R. Gunn, and M.J. Dallwitz. 2000 onwards. Family guide for fruits and seeds: descriptions, illustrations, identification, and information retrieval. Version: 12th April 2021. delta-intkey.com’.
