Including Stephanangaceae DulacExcluding Triplostegiaceae
Habit and leaf form. Herbs (mostly), or shrubs (a few); bearing essential oils (in rhizomes and roots). Annual to perennial; with a basal aggregation of leaves, or with neither basal nor terminal aggregations of leaves; when perennial, rhizomatous (the rhizome usually strongly scented). Stem growth conspicuously sympodial, or not conspicuously sympodial. Helophytic to mesophytic. Leaves opposite; flat; petiolate; connate to not connate; foetid (from mono- and sesquiterpenoid essential oils), or without marked odour; simple, or compound, or simple and compound; when compound, pinnate. Lamina when simple dissected, or entire; when simple/dissected, pinnatifid; pinnately veined; cross-venulate. Leaves exstipulate; without a persistent basal meristem.
Leaf anatomy. Hydathodes present (occasionally), or absent. Stomata present; mainly confined to one surface, or on both surfaces; anomocytic.
Lamina dorsiventral (usually), or isobilateral, or centric. Minor leaf veins with phloem transfer cells (Centranthus, Fedia, Valeriana, Valerianella).
Stem anatomy. Cork cambium present; initially deep-seated. Nodes tri-lacunar. Primary vascular tissue comprising a ring of bundles (these soon becoming linked). Secondary thickening developing from a conventional cambial ring. Xylem with libriform fibres; with vessels. Vessel end-walls simple. Wood parenchyma absent.
Reproductive type, pollination. Plants hermaphrodite, or polygamomonoecious. Pollination entomophilous.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes, in corymbs, and in panicles. The ultimate inflorescence unit cymose. Inflorescences dichotomous cymes, close corymbs etc, not heads; without involucral bracts. Flowers bracteate (usually); usually bracteolate; small; fragrant to malodorous (often sickly-sweet); somewhat irregular to very irregular; zygomorphic. The floral irregularity involving the perianth and involving the androecium. Flowers cyclic; tetracyclic. Free hypanthium absent.
Perianth with distinct calyx and corolla (the calyx usually much reduced at anthesis, but often developing later into a pappus); when determinable, 3–10; 2 whorled; isomerous, or anisomerous. Calyx rarely obviously 5 (Nardostachys, usually not clearly determinable); represented by bristles (often, ultimately), or not represented by bristles; 1 whorled; polysepalous, or gamosepalous (Nardostachys with well developed segments, but usually reduced or obsolete, sometimes represented by inconspicuous teeth, often (e.g. Valeriana) represented by up to 20 segments that are inrolled at anthesis to form a ring around the base of the corolla, unrolling and expanding in the fruit to become setaceous, plumose and pappuslike); entire, or lobulate, or blunt-lobed, or toothed (usually much reduced at anthesis); persistent; accrescent (often forming a pappus in the fruit — e.g. Valeriana). Epicalyx absent. Corolla (3–)5; 1 whorled; gamopetalous; imbricate; funnel-shaped, or tubular; unequal but not bilabiate, or bilabiate, or regular; spurred (often), or not spurred.
Androecium (1–)3(–4). Androecial members adnate; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 1 (the posterior only), or 3 (by suppression of the posterior and a lateral), or 4 (usually, by suppression of the posterior); inserted in the throat of the corolla tube (at least, inserted above the middle); reduced in number relative to the adjacent perianth; oppositisepalous. Anthers dorsifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. Anther wall initially with one middle layer; of the ‘dicot’ type. Tapetum amoeboid. Pollen grains aperturate; 3(–4) aperturate; colporate (colporoidate); 3-celled (in 4 genera).
Gynoecium 3 carpelled. Carpels reduced in number relative to the perianth. The pistil 3 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; inferior. Ovary 3 locular (but only one of the three locules fertile). Gynoecium stylate. Styles 1; apical. Stigmas 1, or 3. Placentation apical. Ovules 1 per locule; pendulous; non-arillate; anatropous; unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; persistent. Synergids commonly hooked. Endosperm formation cellular. Embryogeny asterad.
Fruit non-fleshy; indehiscent; achene-like, or a samara; 1 seeded. Seeds non-endospermic. Embryo well differentiated. Cotyledons 2. Embryo chlorophyllous (2/3); straight.
Seedling. Germination phanerocotylar.
Physiology, biochemistry. Not cyanogenic. Alkaloids present, or absent (4 species listed). Iridoids detected; ‘Route I’ type (normal and seco). Proanthocyanidins absent. Flavonols present; kaempferol (trace). Ellagic acid absent (Valeriana). Aluminium accumulation not found.
Geography, cytology. Temperate to tropical. Almost cosmopolitan, but lacking from tropical Africa, Madagascar, Australasia. X = (7-)9(-12).
Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Corniflorae; Dipsacales. Cronquist’s Subclass Asteridae; Dipsacales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; campanulid; Order Dipsacales (as a synonym of what?).
Species 400. Genera 8; Centranthus, Fedia, Nardostachys, Patrinia, Plectritis, Pseudobetckea, Valeriana (Phyllactis), Valerianella.
• Technical details: Valeriana, Fedia.
• Technical details: Centranthus.
• Technical details: Valeriana (Thonner).
• Valerianella, Centranthus, Valeriana (B. Ent. compilation).