Onagraceae Juss.
Including Circaeaceae Lindl., Epilobiaceae Ventenat, Jussieuaceae Drude, Oenothereae (Oenotheraceae) Endl., Onagrariaceae Dulac
Habit and leaf form. Shrubs and herbs, or trees (rarely, to 30 m); bearing essential oils, or without essential oils. Annual, or biennial, or perennial; with a basal aggregation of leaves, or with neither basal nor terminal aggregations of leaves. Hydrophytic, or helophytic, or mesophytic; when hydrophytic (Ludwigia), rooted. Leaves of Ludwigia emergent and floating. Leaves alternate, or opposite, or whorled; when alternate, spiral; petiolate to sessile; non-sheathing; not gland-dotted; simple; epulvinate. Lamina dissected, or entire; when dissected, pinnatifid; pinnately veined; cross-venulate. Leaves stipulate, or exstipulate. Stipules when present, intrapetiolar; free of one another; caducous. Leaves without a persistent basal meristem.
Leaf anatomy. Mucilaginous epidermis present, or absent. Stomata anisocytic, or tetracytic, or cyclocytic.
Lamina dorsiventral, or centric. The mesophyll without sclerenchymatous idioblasts. Minor leaf veins without phloem transfer cells (6 genera).
Stem anatomy. Cork cambium present; initially deep-seated. Nodes unilacunar. Primary vascular tissue usually bicollateral. Internal phloem commonly present. Secondary thickening developing from a conventional cambial ring, or anomalous; via concentric cambia (?), or from a single cambial ring. ‘Included’ phloem present (commonly), or absent. Xylem without fibre tracheids; with libriform fibres; with vessels. Vessel end-walls horizontal to oblique; simple. Vessels with vestured pits. Wood parenchyma scanty paratracheal.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite (usually). Anemophilous, or entomophilous.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in panicles, in racemes, and in spikes. Inflorescences terminal, or axillary. Flowers small to large; regular to very irregular; (2–)4(–7) merous; cyclic; tricyclic, or tetracyclic, or pentacyclic. Free hypanthium usually present (usually elongated).
Perianth with distinct calyx and corolla (usually), or sepaline (the corolla sometimes absent); 4–8(–14); 1 whorled, or 2 whorled; isomerous. Calyx (2–)4(–7); 1 whorled; gamosepalous; blunt-lobed; lobes valvate. Corolla (2–)4(–7) (rarely absent); 1 whorled; polypetalous; imbricate, or contorted; yellow, or pink, or purple. Petals clawed (often), or sessile; often bilobed (or trilobed).
Androecium 8 (often), or 8–10, or 4, or 2, or 1. Androecial members adnate (to the hypanthium), or free of the perianth (on the disk); all equal, or markedly unequal; free of one another; 2 whorled (often), or 1 whorled. Androecium exclusively of fertile stamens, or including staminodes. Staminodes when present, 1, or 2–4; petaloid (Lopezia), or non-petaloid. Stamens (1–)8(–10); reduced in number relative to the adjacent perianth (rarely), or isomerous with the perianth, or diplostemonous. Anthers dorsifixed; versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate; unappendaged. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Pollen shed in aggregates, or shed as single grains; with viscin strands (often), or without viscin strands; when in aggregates, in tetrads. Pollen grains aperturate; (2–)3(–6) aperturate; colpate, or porate (often), or colporate; 2-celled.
Gynoecium 4(–7) carpelled. Carpels isomerous with the perianth. The pistil 2 celled, or 4–7 celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; inferior, or partly inferior. Ovary 4(–7) locular (when inferior — but the septa often imperfect below), or 2 locular (when half-inferior). Epigynous disk present. Gynoecium stylate. Styles 1; apical. Stigmas 1–4; wet type, or dry type; papillate, or non-papillate; Group II type, or Group III type, or Group IV type. Placentation axile, or parietal. Ovules 1–50 per locule (to ‘many’); pendulous, or ascending; non-arillate; anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Embryo-sac development Oenothera-type. Antipodal cells not formed. Synergids with filiform apparatus. Hypostase commonly present. Embryogeny onagrad.
Fruit fleshy (rarely), or non-fleshy; dehiscent, or indehiscent; a capsule (usually), or a berry, or a nut. Capsules loculicidal, or septicidal. Fruit 2–100 seeded (usually ‘many’). Seeds non-endospermic; conspicuously hairy (sometimes, with a tuft, in Epilobium), or not conspicuously hairy. Cotyledons 2. Embryo achlorophyllous (5/5); straight.
Seedling. Germination phanerocotylar.
Physiology, biochemistry. Cyanogenic, or not cyanogenic. Alkaloids absent (32 species). Iridoids not detected. Proanthocyanidins present (very rarely), or absent; in a species of Jussieua delphinidin. Flavonols present (usually); quercetin, or kaempferol and quercetin, or quercetin and myricetin. Ellagic acid present (11 species, 8 genera). Ursolic acid present. Saponins/sapogenins absent. Aluminium accumulation not found. Sugars transported as oligosaccharides + sucrose (in Hauya). C3. C3 physiology recorded directly in Calylophus, Epilobium, Gaura, Oenothera. Anatomy non-C4 type (Calylophus, Epilobium, Gaura, Oenothera).
Geography, cytology. Frigid zone to tropical. Cosmopolitan, except in arid parts of Australia and Africa. X = (6-)7(-18). Supposed basic chromosome number of family 11 (?).
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Myrtiflorae; Myrtales. Cronquist’s Subclass Rosidae; Myrtales. APG (1998) Eudicot; core Eudicot; Rosid; Eurosid II; Myrtales. Species 640. Genera about 20; Boisduvallia, Calylophus, Camissonia, Circaea, Clarkia, Epilobium, Fuchsia, Gaura, Gayophytum, Gongylocarpus, Hauya, Jussiaea (= Ludwigia), Lopezia, Ludwigia, Oenothera, Stenosiphon, Xylonagra.
Economic uses, etc. Most genera include species cultivated as ornamentals, with Fuchsia contributing many. Fuchsia berries are edible and good.
Illustrations. • Epilobium, Circaea. • Technical details (Epilobium). • Technical details (Circaea, Fuchsia, Ludwigia). • Technical details (Ludwigia).
Quotations
The Conium there, her stalks bedropp’d with red,
Rears, with Circaea, neighbour of the dead
(Charlotte Smith, quoted by
Ann Pratt, ‘Wild Flowers’ (1857) - Circaea lutetiana)
Cite this publication as: ‘L. Watson and M. J. Dallwitz (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 14th December 2000. http://biodiversity.uno.edu/delta/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Watson and Dallwitz (1991) should also be cited (see References).
