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The families of flowering plants

L. Watson and M.J. Dallwitz

Mendonciaceae (Lindau) Bremek.

~ Acanthaceae.

Habit and leaf form. Lianas (with articulated young stems). Leaves opposite; simple. Lamina entire. Leaves exstipulate. Lamina margins entire.

Leaf anatomy. Stomata present; diacytic. Hairs present; eglandular and glandular (cf. Acanthaceae). Lamina without secretory cavities. Cystoliths absent. The mesophyll without sclerenchymatous idioblasts.

Axial (stem, wood) anatomy. Secretory cavities absent. Internal phloem absent. Secondary thickening anomalous. The anomalous secondary thickening via concentric cambia (centripetal, in the form of an internal secondary ring of bundles, in Afromendoncia).

The vessel end-walls simple. ‘Included’ phloem absent.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’ (sometimes in terminal racemes); terminal, or axillary; (bi) bracteolate (the bracteoles large, spathaceous); very irregular; zygomorphic. The floral irregularity involving the androecium, or involving the perianth and involving the androecium. Flowers cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present; intrastaminal; annular (large, cupular).

Perianth with distinct calyx and corolla; theoretically 10; 2 whorled. Calyx reduced, theoretically 5 (?); 1 whorled; gamosepalous; shortly lobulate to blunt-lobed, or entire (then annular or truncate). Calyx lobes markedly shorter than the tube. Calyx open in bud (?); with the median member posterior. Corolla 5; 1 whorled; gamopetalous; contorted; more or less hypocrateriform (not inflated above); unequal but not bilabiate, or regular.

Androecium 4, or 5. Androecial members adnate (to the corolla tube); markedly unequal; free of one another; 1 whorled. Androecium exclusively of fertile stamens, or including staminodes. Staminodes when present, 1; in the same series as the fertile stamens; representing the posterior median member. Fertile stamens representing the posterior-lateral pair and the anterior-lateral pair. Stamens 4; didynamous; reduced in number relative to the adjacent perianth; oppositisepalous; alternating with the corolla members. Pollen shed as single grains. Pollen grains aperturate; 4–6 aperturate; colpate (the colpi very short).

Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled, or 2 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 1 locular (one locule more or less reduced or suppressed), or 2 locular. Gynoecium presumed median; stylate. Styles 1; apical. Stigmas 1, or 2 (the stigmatic lobes often more or less unequal). Placentation when unilocular, parietal; when bilocular, axile. Ovules in the single cavity 2; 2 per locule; funicled; collateral; non-arillate; presumed unitegmic; presumed tenuinucellate.

Fruit fleshy; indehiscent; a drupe (with a thick, bony endocarp); 1 seeded, or 2 seeded (1(–2) locular). Seeds non-endospermic. Embryo well differentiated. Cotyledons 2 (the cotyledons twice folded).

Physiology, phytochemistry. Iridoids not detected. Saponins/sapogenins absent.

Special distinguishing feature. The funicles not as in Acanthaceae.

Geography, cytology. Paleotropical and Neotropical. Tropical. Central and tropical South America, tropical Africa, Madagascar.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Lamiiflorae; Scrophulariales. Cronquist’s Subclass Asteridae; Scrophulariales. APG III core angiosperms; core eudicot; Superorder Asteranae; lamiid. APG IV Order Lamiales (as a synonym of Acanthaceae).

Species 60. Genera 2; Anomacanthus (Gilletiella), Mendoncia.

General remarks. “Intermediate between Bignoniaceae, Pedaliaceae, Thunbergiaceae and Acanthaceae” (Airy Shaw, 1973). The present compilation of comparative data has them differing conspicuously from Acanthaceae sensu stricto (q.v.) in habit, anomalous secondary thickening of stems, drupaceous fruits and the unspecialised seed funicles; also in ‘esoteric characters’ of questionable taxonomic value in view of limited sampling, viz., leaf laminae without cystoliths, and absence of iridoids.

Illustrations. • Mendoncia sellowiana and Afromendoncia (= Mendoncia) gilgiana: Nat Pflanzenfam. iv (1895). • Mendoncia lindaviana (as Afromendoncia: Hook. Ic. Pl. 25, 1896). • Mendoncia puberula, as Mendozia: Martius, Nova Gen. et Spec. Pl. Brasiliensium 3 (1829). • Mendoncia vellosoana, as Mendozia: Martius, Nova Gen. et Spec. Pl. Brasiliensium 3 (1829). • TS stems of Mendoncia velloziana, showing fission of the xylem (Solereder, 1908).

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: 15th April 2018.’.