| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Pentaphylacaceae Engl.

Excluding Ternstroemiaceae, retained in Theaceae in this package but transferred here by APG

Habit and leaf form. Small trees, or shrubs (with mucilage cells in the cortex). Leaves persistent; alternate; leathery; petiolate; non-sheathing; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire. Vegetative buds scaly.

Leaf anatomy. The leaf lamina dorsiventral. Mucilaginous epidermis present. Stomata present; mainly confined to one surface (abaxial); paracytic. Lamina without secretory cavities. The mesophyll containing crystals. The crystals druses and solitary-prismatic.

Axial (stem, wood) anatomy. Young stems with solid internodes. Pith homogeneous. Secretory cavities absent (but with mucilage cells in the cortex). Cork cambium present; initially superficial. 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 mixed wide and narrow.

The wood diffuse porous. The vessels very small (and angular); almost entirely solitary. The vessel end-walls oblique; scalariform. The vessels without vestured pits. The axial xylem with tracheids; without vasicentric tracheids; with fibre tracheids; without septate fibres. The fibres without spiral thickening. The parenchyma apotracheal (diffuse). The secondary phloem not stratified. ‘Included’ phloem absent. The wood not storied.

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

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes. The ultimate inflorescence units racemose. Inflorescences terminal and axillary, or intercalary (somewhat); racemes, often with sterile, leafy tips. Flowers (bi-) bracteolate (the persistent bracteoles appressed to the calyx); small; regular; 5 merous (throughout); cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous; regular; persistent; imbricate. Epicalyx absent (but the calyx closely associated with the bracteoles). Corolla 5; 1 whorled; polypetalous; imbricate; regular.

Androecium 5. Androecial members free of the perianth; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; isomerous with the perianth; oppositisepalous (equalling ir shorter than the petals); alternating with the corolla members; inflexed in bud (later erect); filantherous (the filaments thickened and expanded, especially towards the middle, tapering to their tips, the anthers short). Anthers basifixed; non-versatile; dehiscing via pores (each theca with a terminal pore, opening via a small valve); bilocular (the thecae distinct). Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate (to colporoidate).

Gynoecium 5 carpelled. Carpels isomerous with the perianth. The pistil 5 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 5 locular. Gynoecium stylate. Styles 1; apical; short, stout, persistent. Stigmas 1 (lobed), or 5; if considered one, 5 lobed. Placentation axile to apical. Ovules 2 per locule; pendulous; apotropous (Engler); collateral; somewhat campylotropous, or anatropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle.

Fruit non-fleshy; partly or fully dehiscent; a capsule (rather woody, with a persistent central axis, cf. Theaceae-Theoideae); without fleshy investment external to the original ovary. Capsules loculicidal (to halfway or all the way down, the long-persistent valves with a median septum). Seeds scantily endospermic; more or less winged. Embryo well differentiated. Cotyledons 2. Embryo curved (horseshoe-shaped).

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. Aluminium accumulation demonstrated.

Geography, cytology. Paleotropical. Tropical. South China to Malay Peninsula and Sumatra.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Theiflorae (?); Theales (?). Cronquist’s Subclass Dilleniidae; Theales. APG III core angiosperms; core eudicot; Superorder Asteranae (but this conflicts with the embryology as reported by Davis, 1966). APG IV Order Ericales.

Species 1 (Pentaphylax euryoides). Genera 1; only genus, Pentaphylax.

Illustrations. • Pentaphylax euryoides: Hutchinson.

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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