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Common name: Idiospermum Family.
Number of genera 1. Number of species 1 (Idiospermum australiense (Diels) S. T. Blake).
Angiosperm. Magnoliopsida.
Disseminule an intact or entire fruit, or an embryo.
Fruits
Pistil(s) simple, or compound; 1; 1-pistillate; with carpels united. Fruit anthocarp; simple; pome (Spjut 4 families: Idiospermaceae, Olacaceae, Rhamnaceae, Rosaceae); without persistent central column; with styles(s); at apex; within accessory organ(s); within hypanthium; accrescent; persistent; with hypanthium composed of 2 layers; with hypanthium hard layer over soft layer; with hypanthium fleshy (olive-brown); 1–2-seeded; from 5.1–10 cm long; 5–5.5 cm long; 1–2-carpellate (-3?); with carpels united; with carpels remaining united at maturity; without sterile carpels; not sulcate; in transection terete; apex not beaked; indehiscent. Epicarp 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 (but not Spjut), or crustaceous, or bony (latter 2 Spjut for his drupe); not splitting into 1-seeded pyrenes; smooth; without wing; without operculum; without secretory cavities; without mechanism for seedling escape; without grooves; 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; 25 to less than 50 mm long to 50+ mm long; 40–50 mm long; circular; 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; adnate to epicarp; without embryo surrounded and capped by viscid tissue; without markedly different marginal tissue; without fleshy or leathery layer over hard layer; tight; shiny; 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; without wings; without collar; without operculum; colored; monochrome; membranous; not becoming mucilaginous when wetted; surrounding embryo. Hilum larger than punctate (assumed).
Embryo differentiated from food reserve (no endosperm); well developed; 1 per seed; completely filling testa (no food reserve); at one end of seed not extending into a depression or cup; foliate; with investing cotyledons; with cotyledons abruptly connected to hypocotyl-radicle; without coleorhiza; without simmondsin; without stomata; not green; with 2 or more cotyledons. Cotyledons 3 to 4; well developed; 0.9 times length of embryo (estimated); somewhat to significantly wider than hypocotyl-radicle; 10 times wider than hypocotyl-radicle (or more,estimated); entirely concealing hypocotyl-radicle to partially concealing hypocotyl-radicle; not foliaceous; massive; smooth; with apices entire; with margins separate; basally entire; equal in size; not punctate dotted. Hypocotyl-radicle small; straight; not thickened. Plumule moderately developed; straight.
Distribution
Old World. Australia (Queensland).
Notes
This fruit technically does not meet the Spjut description as follows: An indehiscent simple fruit composed of a fleshy to coriaceous exocarp, the fleshy layer primarily formed by receptacle, hypanthium, or perianth". Idiospermum has brittle receptacle. Mabberley: Fruit large, more or less globose, indehiscent, the receptacle becoming hard without, fleshy within and more or less closed apically by persistent perianth and stamen, pericarp thin and adpressed to receptacle. Cronquist: Fruit "large, globose or depressed globose, indehiscent, the hypanthium becoming somewhat fleshy with a tiny, hard outer layer, essentially closed at the top by the persistent stamens and upper or inner tepals, the pericarp itself relatively thin and appressed to (but distinct from) the hypanthial wall. Seed 1". Pome maybe correct, but check Blake (1972). Cotyledons peltate.
Weed information
No USA noxious weeds.
Listed seeds
No ASOA or ISTA listed seeds.
Accepted genera
Idiospermum S. T. Blake
References specific to this family
Cronquist page 72. Blake, S.T. 1972. No.12. Idiospermum (Idiospermaceae), a new genus and family for Calycanthus australiensis. Contr. Queensland Herb. 12:1–37.
General references
Cronquist, A. 1981. An integrated system of classification of flowering plants, 1,262 p. Columbia University Press, New York, 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, Mabberley, D.J. 1987. The plant-book, 706 p. Cambridge University Press, Cambridge, Spjut, R.W. 1994. A systematic treatment of fruit types. Mem. New York Bot. Gard. 70:1–182.
Illustrations
Poor fruit and seed illustrations. Disseminule illustration(s): fruit, or seed, or embryo. Fruit illustration(s): Blake (1972). Embryo illustration(s): Blake (1972), Karen. Karen's plate number and taxon (taxa): 016: Idiospermum australiense (Diels) S.T. Blake (A).
• Embryo. 1 of 1. Idiospermum australiense (Diels) S. T. Blake: 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’.
