| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Naucleaceae (DC.) Wernh.

~ Rubiaceae.

Habit and leaf form. Trees and shrubs, or lianas. Climbing (sometimes), or self supporting. Mesophytic. Leaves opposite, or whorled; simple. Lamina entire. Leaves stipulate. Stipules interpetiolar, or intrapetiolar (rarely); without colleters; caducous (usually), or persistent (when intrapetiolar). Lamina margins entire.

Leaf anatomy. Minor leaf veins without phloem transfer cells (1 genus).

Axial (stem, wood) anatomy. Internal phloem absent. Secondary thickening developing from a conventional cambial ring.

The vessels without vestured pits. ‘Included’ phloem absent.

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

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in heads. Inflorescences terminal, or axillary; in dense, globose heads. Flowers bracteate, or ebracteate; 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; 1 whorled; gamosepalous; regular; persistent, or not persistent; imbricate, or valvate. Corolla 4, or 5; 1 whorled (usually), or 12 whorled; gamopetalous. Corolla lobes markedly shorter than the tube (the tube long, the lobes short). Corolla imbricate, or valvate; funnel-shaped; regular.

Androecium 4, or 5. Androecial members adnate; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 4, or 5; inserted in the throat of the corolla tube; isomerous with the perianth; oppositisepalous; alternating with the corolla members. Anthers dehiscing via longitudinal slits.

Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; inferior. Ovary 2 locular. Gynoecium transverse (?). Styles 1; apical. Stigmas 1; 1–2 lobed. Placentation axile, or apical. Ovules 1–50 per locule (i.e. to ‘many’); pendulous (‘or attached to the middle of the septum’); non-arillate.

Fruit fleshy, or non-fleshy; dehiscent (usually), or indehiscent; a capsule. Gynoecia of adjoining flowers more or less combining to form a multiple fruit. The multiple fruits coalescing (fleshy), or not coalescing (dry). Seeds endospermic. Endosperm oily. Seeds minute (usually flattened).

Physiology, phytochemistry. Iridoids detected (S.R. Jensen, unpublished); ‘Route I’ type. Aluminium accumulation demonstrated.

Geography, cytology. Tropical. Pantropical?.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Gentianiflorae; Gentianales. Cronquist’s Subclass Asteridae; Rubiales. APG III core angiosperms; core eudicot; Superorder Asteranae; lamiid. APG IV Order Gentianales (as a synonym of Rubiaceae).

Species 200. Genera about 10; Adina, Breonia (inc. Platanocephalus, Anthocephalus), Cephalanthus, Mitragyna (inc. Stephegyne), Nauclea, Neonauclea, Sarcocephalus, Uncaria.

General remarks. Seemingly aberrant Rubiaceae, differing according to the present compilation only in the stipules without colleters and the multiple fruits (and unconvincingly in homostyly and vessels without vestured pits).

Illustrations. • Adina pilulifera (as A. globiflora): Bot. Reg. 895, 1825. • Breonia chinensis, as Anthocephalus indicus: Koorders and Valeton, Atlas der Baumgarten von Java 3 (1915). • Cephalanthus natalensis: Bot. Mag. 121 (1895). • Nauclea parvifolia: Wight, Ill. of Indian Botany 2 (1850). • Uncaria gambir: Köhler’s Medizinal Pflanzen 2 (1890). • Uncaria sinensis: Hook. Ic. Pl. 20 (1891). • Sketches.

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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