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The families of flowering plants

L. Watson and M.J. Dallwitz

Resedaceae S.F. Gray

Including Asterocarpaceae Kerner

Habit and leaf form. Herbs (mostly), or shrubs (a few). Annual, or biennial, or perennial; with a basal aggregation of leaves, or without conspicuous aggregations of leaves. Mesophytic, or xerophytic. Leaves alternate; spiral; petiolate to sessile; non-sheathing; simple; epulvinate. Lamina dissected (sometimes deeply so), or entire; when dissected pinnatifid, or palmatifid (sometimes trifid); one-veined, or pinnately veined. Leaves stipulate. Stipules intrapetiolar; free of one another; represented by glands. Leaf development not ‘graminaceous’.

Leaf anatomy. The leaf lamina without clear differentiation into palisade and spongy mesophyll, bifacial to centric (see illustration). Mucilaginous epidermis present, or absent. Stomata present; anomocytic (sometimes accompanied by myrosin cells). Hairs present; eglandular; unicellular. The mesophyll generally without crystals. Minor leaf veins without phloem transfer cells (Reseda).

Axial (stem, wood) anatomy. Young stems with solid internodes, or with hollow internodes. Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening absent (sometimes?), or developing from a conventional cambial ring. Primary medullary rays narrow.

The wood diffuse porous. The vessel end-walls simple. The vessels without vestured pits. The axial xylem without fibre tracheids; with libriform fibres.

Reproductive type, pollination. Plants hermaphrodite (usually), or androdioecious (sometimes, by abortion, in Ochradenus).

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes and in spikes. The ultimate inflorescence units racemose. Inflorescences racemes and spikes. Flowers bracteate; ebracteolate; small to medium-sized; very irregular; zygomorphic. The floral irregularity involving the perianth and involving the androecium. Floral receptacle (usually?) developing an androphore (often with the extra-staminal disk more strongly developed posticously), or developing a gynophore, or developing an androphore and developing a gynophore. Free hypanthium absent.

Perianth with distinct calyx and corolla, or sepaline (petals sometimes lacking); (4–)12(–16); 2 whorled (usually), or 1 whorled; anisomerous (often), or isomerous (sometimes?). Calyx (4–)6(–8); 1 whorled; polysepalous, or gamosepalous (sometimes more or less connate below); unequal but not bilabiate (sometimes), or regular; persistent; imbricate (slightly), or valvate. Corolla when present, (2–)6(–8); 1 whorled; polypetalous (usually), or gamopetalous (rarely connate); valvate, or with open aestivation; unequal but not bilabiate (with the innermost, posterior member larger, the outer members usually progressively smaller and with fewer appendages); white, or yellow; persistent, or deciduous. Petals clawed (usually, broadly so, with scalelike appendages); (at least the innermost largest, usually) fringed, or deeply bifid.

Androecium 3–50 (or more — the number very indefinite). Androecial members theoretically maturing centrifugally; free of the perianth; markedly unequal (the posterior members usually shorter), or all equal; free of one another (usually), or coherent; in Oligomeris, 1 adelphous. Androecium exclusively of fertile stamens. Stamens 3–50 (or more); isomerous with the perianth to polystemonous. Anthers dehiscing via longitudinal slits; introrse; tetrasporangiate. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral. Pollen grains aperturate; 3 aperturate; colpate, or colporate (colporoidate); 2-celled (in Reseda).

Gynoecium (2–)3–6(–7) carpelled. The pistil when syncarpous, 1 celled. Gynoecium apocarpous to syncarpous; eu-apocarpous (Sesamoides), or semicarpous (Caylusea), or synovarious (usually); superior. Carpel in Sesamoides and Caylusea incompletely closed; in Sesamoides 1(–2) ovuled. Placentation in Sesamoides basal. Ovary usually syncarpous and 1 locular. The ‘odd’ carpel posterior. Gynoecium non-stylate. Stigmas (2–)3–6(–7); commissural, or dorsal to the carpels and commissural; dry type; non-papillate; Group II type. Placentation parietal (usually), or basal (Caylusia). Ovules in the single cavity 5–100 (‘few to many’); pendulous, or ascending; with ventral raphe; arillate, or non-arillate; hemianatropous, or campylotropous; bitegmic; tenuinucellate, or crassinucellate. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids hooked. Endosperm formation nuclear. Embryogeny onagrad.

Fruit fleshy, or non-fleshy; an aggregate (sometimes, the carpels spreading), or not an aggregate. The fruiting carpel of Sesamoides a follicle. Fruit indehiscent; capsular-indehiscent (but apically open), or a berry. Seeds more or less non-endospermic; reniform. Embryo well differentiated. Embryo chlorophyllous (2 species of Reseda); curved, or bent. The radicle dorsal.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Ochradenus, Reseda. Anatomy non-C4 type (Ochradenus, Reseda). Mustard-oils present. Cyanogenic, or not cyanogenic. Iridoids not detected. Proanthocyanidins absent. Flavonols present, or absent; kaempferol, or kaempferol and quercetin. Ellagic acid absent (3 Reseda species). Aluminium accumulation not found. Sieve-tube plastids S-type.

Special distinguishing feature. The young, syncarpous unilocular gynoecium and later the capsule open (usually), or gynoecium and fruit not open as in typical Resedaceae.

Geography, cytology. Temperate to sub-tropical. Southwest Eurasia, Mediterranean, North Africa and Middle East, South Africa, Southwest U.S.A. and Mexico. X = 6–15.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Violiflorae; Capparales. Cronquist’s Subclass Dilleniidae; Capparales. APG III core angiosperms; core eudicot; Superorder Rosanae; malvid. APG IV Order Brassicales.

Species 70. Genera 6; Caylusea, Ochradenus, Oligomeris, Randonia, Reseda, Sesamoides.

Illustrations. • Le Maout and Decaisne: Reseda, Randonia, Ochradenus. • Oligomeris glaucescens: Thonner. • Reseda lutea, R. alba (as R. suffruticulosa) and R. luteola: Eng. Bot. 162–164, 1864. • Reseda (B. Ent.). • Oligomeris subulata: TS leaf and surface view of epidermis (Solereder).

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.’.