The families of flowering plants

L. Watson and M.J. Dallwitz

Mastixiaceae Van Tiegh.

~ Cornaceae.

Habit and leaf form. Trees; resinous. Leaves evergreen; (sub-) opposite (or decussate), or alternate to opposite; leathery; petiolate; simple. Lamina entire; cross-venulate; attenuate at the base, or cuneate at the base. Leaves exstipulate. Lamina margins entire. Domatia occurring in the family (seen in 3 species); manifested as pits (by contrast with those recorded in Cornaceae).

General anatomy. Plants without ‘crystal sand’.

Leaf anatomy. The leaf lamina dorsiventral (the palisade of 1 or 2 layers). Stomata mainly confined to one surface (abaxial); anomocytic. Hairs present (unicellular, 2–armed, not lime-encrusted). Adaxial hypodermis absent. Lamina with secretory cavities (or canals). The mesophyll with sclerenchymatous idioblasts.

Axial (stem, wood) anatomy. Secretory cavities present (or canals, in the cortex and pith). Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles (leaf traces) present. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring.

The wood diffuse porous. The vessel end-walls oblique; scalariform (with numerous fine bars). The axial xylem with fibre tracheids. The parenchyma apotracheal. The secondary phloem not stratified (but including fibres). ‘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 panicles. The ultimate inflorescence units cymose. Inflorescences terminal; terminal dichotomous thyrses. Flowers bracteate; (bi-) bracteolate (the pedicels articulated); regular; 4–5 merous; cyclic; tetracyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla; 8, or 10; 2 whorled; isomerous. Calyx 4, or 5(–7); gamosepalous; regular; persistent; open in bud. Corolla 4, or 5(–6); 1 whorled; polypetalous; usually more or less valvate (the petal tips inflexed); regular; fleshy. Petals bilobed, or fringed.

Androecium 4, or 5(–6), or 8. Androecial members free of the perianth; all equal; free of one another; 1 whorled, or 2 whorled (when 8). Androecium exclusively of fertile stamens. Stamens 4, or 5(–6), or 8; isomerous with the perianth, or diplostemonous; oppositisepalous; erect in bud; filantherous (the filaments subulate, flattened). Anthers dorsifixed; dehiscing via longitudinal slits; latrorse; slightly appendaged to unappendaged. The anther appendages when manifest, apical (by slight prolongation of the connective). Pollen grains aperturate; 3 aperturate; colporate.

Gynoecium ostensibly 1 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium monomerous (ostensibly), or syncarpous (i.e. considered pseudomonomerous); ostensibly of one carpel, or eu-syncarpous (if treated as pseudomonomerous); inferior. Carpel stylate; apically stigmatic (the style short, conical, with a punctiform stigma); 1 ovuled. Placentation apical. Ovary if considered syncarpous, 1 locular. Epigynous disk present (fleshy, intrastaminal). Gynoecium stylate. Styles 1 (stout); apical. Stigmas 1 (punctiform deeply bifid or lobed); 2 lobed, or 4–5 lobed. Placentation apical. Ovules in the single cavity 1; pendulous; epitropous; with ventral raphe; anatropous; unitegmic; crassinucellate.

Fruit fleshy. The fruiting carpel indehiscent; drupaceous (ovoid, with the endocarp grooved). Fruit treated as a syncarp, indehiscent; a drupe (with purple or blue pericarp). The drupes with one stone (the endocarp grooved). Fruit 1 seeded. Seeds copiously endospermic (the endosperm fleshy). Cotyledons 2 (foliaceous). Embryo small.

Physiology, phytochemistry. Iridoids detected; ‘Route I’ type. Aluminium accumulation demonstrated.

Geography, cytology. Paleotropical. Tropical. Indomalayan.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Corniflorae; Cornales. Cronquist’s Subclass Rosidae; Cornales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; Order Cornales (as a synonym of Cornaceae).

Species 25. Genera 1; only genus, Mastixia.

General remarks. These compiled descriptions show Mastixia differing from Cornaceae sensu stricto (q.v.) in the latrorse, sometimes appendaged anthers and the (pseudo)monomerous ovary with apical placentation and epitropous ovules, as well as in vegetative-anatomical characters depending on limited sampling. See Matthew 1976.

Illustrations. • Mastixia acuminatissima, M. bracteata, M. scortechinii and M. trichotoma: technical details. Das Pflanzenreich, 1910).

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: 13th March 2017.’.