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The families of flowering plants

L. Watson and M.J. Dallwitz

Stegnospermataceae (H. Walter) Nak.

Alternatively Stegnospermaceae; ~ Phytolaccaceae.

Habit and leaf form. Shrubs, or lianas. Plants succulent. Self supporting, or climbing. Xerophytic. Leaves alternate; fleshy; petiolate; non-sheathing; simple. Lamina entire; elliptic or oblong to ovate, or obovate; pinnately veined. Leaves exstipulate. Lamina margins entire (membranous).

Axial (stem, wood) anatomy. Internal phloem absent. Secondary thickening anomalous. The anomalous secondary thickening via concentric cambia.

The axial xylem with tracheids. ‘Included’ phloem present.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes, or in panicles (racemiform). The ultimate inflorescence units cymose. Inflorescences terminal, or axillary; terminal racemiform thyrses or axillary cymes. Flowers bracteate; bi- bracteolate (the pedicels thickened upwards); regular; 5 merous; cyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous; regular; persistent; imbricate. Corolla 5 (shorter than the sepals); 1 whorled; polypetalous; imbricate; regular. Petals suborbicular, slightly clawed.

Androecium 10. Androecial members free of the perianth (the oppositisepalous members), or adnate (the alternisepalous members being basally joined to the petals); coherent; 1 adelphous (the filaments connate at the base); 1 whorled. Androecium exclusively of fertile stamens. Stamens 10; diplostemonous; both alternating with and opposite the corolla members; filantherous (the filaments subulate). Anthers dorsifixed; dehiscing via longitudinal slits; introrse. Pollen grains aperturate; 3 aperturate; colpate.

Gynoecium 3–5 carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil 1 celled. Gynoecium syncarpous; synstylovarious. Ovary 1 locular (the partitions ephemeral). Stigmas 3–5 (short, recurved). Placentation basal and free central (the ovules basal around a central column). Ovules in the single cavity 3–5 (as many as the stigmas); ascending; arillate; amphitropous.

Fruit non-fleshy; dehiscent; a capsule (leathery). Capsules 3–5 valvular (the valves opposite the sepals). Fruit 1–5 seeded (the seeds almost covered by the large, fleshy arils). Seeds non-endospermic. Perisperm present (mealy). Seeds with starch. Embryo well differentiated. Embryo curved.

Physiology, phytochemistry. Betalains present. Ellagic acid present. Sieve-tube plastids P-type; type III (b: with a polyhedral protein crystalloid, as well as the subperiferal proteinaceous filaments).

Geography, cytology. Neotropical. Sub-tropical to tropical. Mexico, Central America, West Indies.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Caryophylliflorae; Caryophyllales. Cronquist’s Subclass Caryophyllidae; Caryophyllales. APG III core angiosperms; core eudicot; Superorder Caryophyllanae. APG IV Order Caryophyllales.

Species 5. Genera 1; only genus, Stegnosperma.

Illustrations. • Stegnosperma halimifolium: Bentham in Voyage of HMS Sulphur (1844). • Stegnosperma halimifolium: 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: 15th April 2018.’.