| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Tremandraceae DC.

Alternatively Tremandreae (Tremandraceae) R. Br.; ~ Elaeocarpaceae.

Including Tetrathecaceae R. Br.

Habit and leaf form. Small shrubs, or herbs (slender heathlike subshrubs, or subherbaceous). ‘Normal’ plants, or switch-plants; sometimes with the principal photosynthesizing function transferred to stems. Leaves well developed, or much reduced, or absent. Perennial. Mesophytic, or xerophytic. Leaves minute, or small; alternate, or opposite, or whorled; flat, or rolled (often ericoid); ‘herbaceous’, or leathery, or membranous; imbricate (often), or not imbricate; petiolate to sessile; non-sheathing; simple. Lamina entire; one-veined, or pinnately veined; cross-venulate, or without cross-venules. Leaves exstipulate (as usually interpreted, but often with glands at the stipular positions). Lamina margins entire, or dentate. Leaf development not ‘graminaceous’.

Leaf anatomy. The leaf lamina dorsiventral (with one layer of palisade). Mucilaginous epidermis present (commonly), or absent. Stomata present; mainly confined to one surface (abaxial); anomocytic. Hairs present (simple unicellular, stellate, eglandular and glandular forms recorded). The mesophyll containing crystals. The crystals druses, or solitary-prismatic (mainly).

Axial (stem, wood) anatomy. Pith homogeneous to heterogeneous. Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow.

The wood diffuse porous. The vessels very to extremely small; solitary, radially paired, and in radial multiples. The vessel end-walls simple (mostly), or scalariform and simple. The vessels without vestured pits; with spiral thickening (sometimes), or without spiral thickening. The axial xylem with fibre tracheids, or without fibre tracheids; with libriform fibres; including septate fibres, or without septate fibres. The fibres without spiral thickening. The parenchyma scanty paratracheal (or absent); wood not storied.

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers slender-pedunculate, solitary, or aggregated in ‘inflorescences’; when solitary, axillary. Inflorescences when flowers grouped, axillary (with 2–4 flowers per axil). Flowers bracteate (at the peduncle base); small; regular; (3–)4 merous, or 5 merous; cyclic; tetracyclic (i.e., if the stamens are interpreted as one whorl). Free hypanthium absent. Hypogynous disk present, or absent.

Perianth with distinct calyx and corolla; 6, or 8, or 10; 2 whorled; isomerous. Calyx (3–)4–5; 1 whorled; polysepalous (usually), or gamosepalous; regular; valvate; with the median member posterior. Corolla (3–)4–5; 1 whorled; polypetalous; induplicate valvate; regular; white, or pink, or purple.

Androecium 6 (rarely), or 8, or 10. Androecial members branched (this being a reasonable interpretation of the antepetalous pairs), or unbranched (as conventionally interpreted); free of the perianth; free of one another, or coherent; if coherent, 4 adelphous, or 5 adelphous (interpreting the pairs as ‘bundles’); 1 whorled (seemingly, though twice the corolla in number). The androecial bundles if interpreted as such, opposite the corolla members. Androecium exclusively of fertile stamens. Stamens 6 (rarely), or 8, or 10; diplostemonous; alternisepalous (in antepetalous pairs); opposite the corolla members; erect in bud; filantherous (with short filaments). Anthers basifixed; non-versatile; dehiscing via pores (with a single apical pore, this often at the top of a more or less elongated tube); four locular; tetrasporangiate (the sporangia sometimes in a single row); appendaged (i.e., with an apical pore-tipped tube), or unappendaged. Pollen grains aperturate; 3 aperturate; colporate (or colporoidate); 2-celled.

Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 2 locular. Gynoecium median; stylate. Styles 1; apical. Placentation axile, or apical. Ovules 1–2(–5) per locule; pendulous; epitropous; with ventral raphe; arillate (usually), or non-arillate (Platytheca); anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Antipodal cells formed; 3; not proliferating.

Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal, or septicidal and loculicidal. Seeds endospermic; winged (via a twisted appendage), or wingless. Cotyledons 2 (?). Embryo straight.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. Cyanogenic, or not cyanogenic. Alkaloids present, or absent (2 species listed). Iridoids not detected. Proanthocyanidins absent. Flavonols present; quercetin and myricetin. Ellagic acid present (Tetratheca), or absent (Platytheca). Aluminium accumulation not found.

Geography, cytology. Temperate to tropical. Australia.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Araliiflorae (?); Pittosporales (?). Cronquist’s Subclass Rosidae; Polygalales. APG III core angiosperms; core eudicot; Superorder Rosanae; fabid. APG IV Order Oxalidales (as a synonym of Elaeocarpaceae).

Species about 45. Genera 3; Platytheca, Tetratheca, Tremandra.

General remarks. The data compiled for this package have Tremandraceae differing from Elaeocarpaceae (q.v.) in the exstipulate leaves, the diplostemonous androecium with fewer stamens and 4-locular anthers, and seeds with a straight embryo; also in ‘esoteric characters’ relying on limited sampling (unilacunar nodes, xylem with libriform fibres, no proanthocyanidins).

Illustrations. • Tremandra stelligera and T. diffusa, Platytheca galioides, Tetratheca affinis, T. gunnii, T. juncea and T. virgata: Nat. Pflanzenfam. 3 (1896). • Le Maout and Decaisne: Platytheca galioides (as Tetratheca verticillata) and Tetratheca procumbens. • Tetratheca hirsuta: Lindley. • Tetratheca hirsuta: Bot. Reg. 1844, 67. Tetratheca hirsuta. 1, flower with calyx and corolla removed. Each stamen exhibits a terminal tube with an apical dehiscence pore. 2, gynoecium with one side of the ovary cut away, showing a pendulous ovule with terminal appendage (the latter representing the incipient wing of the seed). • Tetratheca gunnii and T. procumbens: Hook. Fl. Tas (1860). • Tetratheca thymifolia: Bot. Mag. 131 (1905).

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, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 8th June 2026. delta-intkey.com’.

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