The families of flowering plants
Including Stephanangaceae Dulac.; excluding Triplostegiaceae.
Habit and leaf form. Herbs (mostly), or shrubs (a few); bearing essential oils (at least in rhizomes and roots). Annual to perennial; with a basal aggregation of leaves, or without conspicuous 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; leaf development not graminaceous.
Leaf anatomy. The leaf lamina dorsiventral (usually), or bifacial, or centric. Hydathodes present (occasionally), or absent. Stomata present; mainly confined to one surface (abaxial), or on both surfaces (commonly); anomocytic. Hairs present; eglandular (unicellular or sometimes transversely septate, usually twaled), or glandular (with unicellular or multicellular stalks and small multicellular heads). Lamina without secretory cavities. The mesophyll without crystals (or very rare, but alcohol treatment sometimes reveals sphaerocrystalline masses perhaps representing inulin). Minor leaf veins with phloem transfer cells (Centranthus, Fedia, Valeriana, Valerianella).
Axial (stem, wood) anatomy. Young stems with hollow internodes. Cork cambium present (rarely, e.g. in Centranthus), or absent; where found, initially deep-seated. Nodes tri-lacunar. Primary vascular tissues comprising a ring of bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring (the primary bundes soon becoming linked by prosenchymatous elements and a narrow ring of phloem).
The wood diffuse porous. The vessels very small; in radial multiples (these long). The vessel end-walls rather oblique; simple. The vessels without vestured pits; without spiral thickening. The axial xylem with tracheids; with vasicentric tracheids; without fibre tracheids; with libriform fibres; without septate fibres. The fibres without spiral thickening. The 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 units cymose. Inflorescences dichotomous cymes, close corymbs etc., but 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 exhibits well developed segments, but they are usually reduced or obsolete, sometimes being represented by inconspicuous teeth, or 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 pappus-like); 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 member only), or 3 (by suppression of the posterior and a lateral), or 4 (usually, by suppression of the posterior one); 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 with 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, phytochemistry. 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. Dahlgrens Superorder Corniflorae; Dipsacales. Cronquists Subclass Asteridae; Dipsacales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; campanulid; Order Dipsacales.
Species 400. Genera 8; Centranthus, Fedia, Nardostachys, Patrinia, Plectritis, Pseudobetckea, Valeriana (Phyllactis), Valerianella.
General remarks. Differing from Caprifoliaceae sensu stricto (q.v.) in leaf anatomy, xylem details and assorted floral, fruit seed and embryological characters.
Illustrations. • Technical details: Valeriana, Fedia. • Technical details: Centranthus. • Technical details: Valeriana (Thonner). • Valerianella, Centranthus, Valeriana (B. Ent. compilation).
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: 19th October 2016. delta-intkey.com’.