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The families of flowering plants

L. Watson and M.J. Dallwitz

Nitrariaceae Bercht & J. Presl

Excluding Peganiaceae, Tetradiclidaceae.

Habit and leaf form. Shrubs (sometimes spiny). Plants succulent. Xerophytic (in salt deserts). Leaves deciduous; alternate; spiral (or fasciculate); fleshy; petiolate, or subsessile; non-sheathing; simple; epulvinate. Lamina dissected (apically trifid), or entire; if dissected, palmatifid; one-veined, or palmately veined. Leaves stipulate. Stipules intrapetiolar; free of one another; small; caducous (often), or persistent.

Leaf anatomy. The leaf lamina dorsiventral, or bifacial (?), or centric. Mucilaginous epidermis absent (?). Stomata present; anomocytic (mainly), or paracytic, or actinocytic. Hairs present; eglandular; unicellular. Unicellular hairs simple. Complex hairs absent. The mesophyll containing mucilage cells; with sclerenchymatous idioblasts, or without sclerenchymatous idioblasts (?); containing crystals. The crystals druses and solitary-prismatic.

Axial (stem, wood) anatomy. Secretory cavities present; with mucilage. Primary vascular tissues in a cylinder, without separate bundles. Secondary thickening developing from a conventional cambial ring, or anomalous (?).

The vessel end-walls horizontal to oblique; simple. The axial xylem without fibre tracheids; with libriform fibres. The parenchyma paratracheal. ‘Included’ phloem absent.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in cymes (these scorpioid). The ultimate inflorescence units cymose. Inflorescences once or twice forked scorpioid cymes. Flowers bracteate (the bracts caducous); ebracteolate; small (less than 1 cm long); regular; more or less 5 merous; cyclic; polycyclic. Free hypanthium present.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous (?), or gamosepalous (‘connate below’); regular; fleshy; persistent; non-accrescent; imbricate. Corolla 5; 1 whorled; polypetalous (the petals concave, with inflexed apices); (induplicate-) valvate; regular; white.

Androecium (10–)15. Androecial members free of the perianth (on the hypanthium); free of one another; 3 whorled (?). Stamens (10–)15 (usually three times the number of petals); triplostemonous; both alternating with and opposite the corolla members. Anthers dorsifixed; versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Pollen grains aperturate.

Gynoecium 2–6 carpelled. Carpels reduced in number relative to the perianth, or isomerous with the perianth, or increased in number relative to the perianth. The pistil 2–6 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 2–6 locular; sessile. Gynoecium stylate. Styles 1; attenuate from the ovary; apical. Stigmas or stigmatic lines as many as the locules. Placentation axile to apical. Ovules differentiated; 1 per locule; long funicled; pendulous; apotropous; with ventral raphe; non-arillate; anatropous; bitegmic.

Fruit fleshy; indehiscent; a drupe (often edible, purple, red or yellow). The drupes with one stone (by abortion). Fruit 1 seeded. Seeds non-endospermic. Cotyledons 2. Embryo chlorophyllous; straight (the radicle next to the hilum).

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Nitraria. Anatomy non-C4 type. Mustard-oils present, or absent (not specified, in descriptions seen, though it would seem important to know). Not cyanogenic. Iridoids not detected. Proanthocyanidins absent. Flavonols present. Aluminium accumulation not found.

Geography, cytology. Holarctic, Paleotropical, and Australian. Sahara and southern Russia to Afghanistan and E. Siberia, one in southern Australia.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rutiflorae; Sapindales (re-assigned). Cronquist’s Subclass Rosidae; Sapindales. APG III core angiosperms; core eudicot; Superorder Rosanae; malvid. APG IV Order Sapindales.

Species 9. Genera 1; Nitraria.

General remarks. Sheahan and Chase (1996) recommended recognising this family as belonging to the order Sapindales, and not closely related to Zygophyllaceae s. str. (q.v.). The descriptions compiled for the present package depict 15 conspicuous differences from Peganaceae (q.v.), involving habit, leaf form, floral, fruit and seed characters. Based on limited sampling, they also suggest several differences in leaf anatomy.

Illustrations. • Nitraria schoberi and N. retusa: Nat. Pflanzenfam. 3 (1896). • Nitraria schoberi: Lodiges Bot. Cab. (1828).

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: 5th March 2018.’.