The families of flowering plants

L. Watson and M.J. Dallwitz

Peganaceae Tiegh. ex Takht.

~ Nitrariaceae.

Habit and leaf form. Glabrous or hairy herbs (with terete stems). Perennial (branched); without conspicuous aggregations of leaves. Leaves alternate; spiral; ‘herbaceous’, or leathery, or fleshy (?); sessile; non-sheathing; simple; epulvinate. Lamina dissected, or entire; when dissected, more or less irregularly pinnatifid; pinnately veined. Leaves stipulate, or exstipulate (Malacocarpus?). Stipules intrapetiolar; free of one another; setaceous; caducous.

Leaf anatomy. The leaf lamina dorsiventral, or bifacial (?). Mucilaginous epidermis present, or absent. Stomata present; anomocytic. Hairs present; glandular; multicellular. Multicellular hairs simple. Complex hairs present; capitate. Adaxial hypodermis present, or absent. The mesophyll not containing mucilage cells; without sclerenchymatous idioblasts (these also lacking in the stems); containing crystals. The crystals raphides, or druses, or solitary-prismatic.

Axial (stem, wood) anatomy. Secretory cavities absent (or at least, no mucilage cavities). Primary vascular tissues in a cylinder, without separate bundles. Secondary thickening developing from a conventional cambial ring (?).

The vessel end-walls horizontal to oblique; simple. The axial xylem without fibre tracheids; with libriform fibres.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’ (towards the ends of the stems); leaf-opposed. Inflorescences or one-flowered peduncles leaf-opposed. Flowers small to medium-sized; regular; 4–5 merous; polycyclic. Floral receptacle developing a gynophore, or with neither androphore nor gynophore (?). Hypogynous disk present; intrastaminal; annular.

Perianth with distinct calyx and corolla; 8, or 10; 2 whorled; isomerous. Calyx 4, or 5; 1 whorled; polysepalous (?); regular; non-fleshy; persistent (often leafy and pinnatifid); valvate. Corolla 4, or 5; 1 whorled; polypetalous; imbricate; more or less regular; white.

Androecium 12, or 15. Androecial members free of the perianth; free of one another; 3 whorled. Androecium exclusively of fertile stamens. Stamens 12, or 15; triplostemonous; both alternating with and opposite the corolla members; filantherous (the filaments dilated basally). Pollen grains aperturate.

Gynoecium 2–3 carpelled. Carpels reduced in number relative to the perianth. The pistil 2–3 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 2–3 locular; subsessile. Gynoecium stylate. Styles 1; from a depression at the top of the ovary; apical. Stigmas 1 (with 2–3 stigmatic ridges); dry type; papillate; Group II type. Placentation axile to apical. Ovules differentiated; 10–50 per locule (‘many’); funicled; pendulous; apotropous; with ventral raphe; non-arillate; anatropous (?); bitegmic.

Fruit fleshy, or non-fleshy; dehiscent (Peganum), or indehiscent (Malacocarpus); a capsule, or a berry. Capsules of Peganum loculicidal. Fruit 10–100 seeded (‘many’). Seeds endospermic. Cotyledons 2. Embryo chlorophyllous; curved.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Peganum. Anatomy non-C4 type. Mustard-oils present, or absent (? - not specified in descriptions seen, though it would be taxonomically helpful to know). Alkaloids present.

Geography, cytology. Holarctic and Neotropical. Temperate and sub-tropical. Mediterranean to Mongolia, southern U.S. and Mexico.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rutiflorae; Sapindales (re-assigned). Cronquist’s Subclass Rosidae; Sapindales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Sapindales (as a synonym of Nitrariaceae).

Species 5–7. Genera 2; Malacocarpus, Peganum.

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 Nitrariaceae, involving habit, leaf form, floral, fruit and seed characters; and based on limited sampling, they also show several differences in leaf anatomy.

Economic uses, etc. A dye (‘Turkey red’) from the seeds is used for dyeing hats (tarbooshes).

Illustrations. • Peganum harmala: Baillon, Histoire des plantes 4 (1873).

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.’.