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The families of flowering plants.                                                                                                                                                                

Escalloniaceae Dum.

                        

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~Saxifragaceae or Grossulariaceae in many older works

IncludingPolyosmaceae BlumeExcluding Abrophyllaceae T. Nakai,, Argophyllaceae,Carpodetaceae, Eremosynaceae, Ixerbaceae, Polyosmaceae,Rousseaceae, Tribelaceae

Habit and leaf form. Shrubs, or trees;non-laticiferous and without coloured juice. Plants non-succulent;autotrophic. Mesophytic. Leaves alternate, or opposite, or whorled; ‘herbaceous’, or leathery, or fleshy; petiolate; not connate; non-sheathing; not gland-dotted; simple; epulvinate. Lamina entire;pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins crenate, or serrate, or dentate (the teeth mostly gland-tipped). Vegetative buds scaly, or not scaly. Leaves without a persistent basal meristem.

Leaf anatomy. Stomata present; anomocytic (mostly), or paracytic, or cyclocytic. Hairs present; unicellular.

Adaxial hypodermis present (commonly), or absent. Lamina dorsiventral; without secretory cavities. Minor leaf veins without phloem transfer cells (Escallonia).

Stem anatomy. Secretory cavities absent. Cork cambium present; initially deep-seated, or superficial. Nodes unilacunar, or tri-lacunar. Secondary thickening developing from a conventional cambial ring. Xylem with tracheids. Vessel end-walls scalariform. Primary medullary rays tending to be mixed wide and narrow. Wood parenchyma apotracheal (diffuse).

Reproductive type, pollination. Fertile flowershermaphrodite. Unisexual flowers absent. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’. The ultimate inflorescence unit cymose, or racemose. Flowers regular; (4–)5(–6) merous; cyclic. Floral receptacle with neither androphore nor gynophore. Free hypanthium present, or absent. Hypogynous disk present.

Perianthwith distinct calyx and corolla; (8–)10(–12); 2 whorled; isomerous. Calyx(4–)5(–6); 1 whorled; polysepalous, or gamosepalous; regular; persistent;imbricate, or valvate; with the median member posterior. Corolla (4–)5(–6); 1 whorled; not appendiculate; polypetalous (nearly always), or gamopetalous (rarely, with a short tube). Corolla lobes markedly longer than the tube. Corolla imbricate, or valvate; regular. Petals clawed, or sessile.

Androecium (4–)5(–6), or (8–)10(–12). Androecial members free of the perianth (perigynous); free of one another; 1 whorled, or 2 whorled. Androecium exclusively of fertile stamens (when only one whorl), or including staminodes (when two whorls). Staminodes when present, (4–)5(–6). Stamens (4–)5(–6);isomerous with the perianth; (fertile) oppositisepalous; alternating with the corolla members. Anthers dorsifixed; dehiscing via longitudinal slits; introrse. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate.

Gynoecium 1–6 carpelled. Carpels reduced in number relative to the perianth (usually), or isomerous with the perianth. The pistil when syncarpous, 1 celled, or 2–6 celled. Gynoecium apocarpous (rarely), or syncarpous; eu-apocarpous (rarely), or semicarpous to eu-syncarpous; superior to inferior. Carpel (when apocarpous) 15–100 ovuled (‘many’). Placentation when apocarpous marginal. Ovary when syncarpous 1 locular, or 2–6 locular. Gynoecium in Escallonia median; stylate. Styles 1–6; without an indusium; apical. Stigmaswet type; non-papillate; Group IV type. Placentation when unilocular parietal; when plurilocular axile. Ovules in the single cavity when unilocular, 15–100 (‘many’); when plurilocular, 15–50 per locule (‘many’); anatropous; unitegmic (Escallonia); tenuinucellate (in Escallonia and Polyosma). Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids elongated. Endosperm formation nuclear.

Fruit fleshy, or non-fleshy; dehiscent, or indehiscent; a capsule, or a berry;without fleshy investment. Seeds copiously endospermic.

Physiology, biochemistry. Not cyanogenic. Iridoids detected; ‘Route I’ type (normal and seco). Proanthocyanidins present, or absent; when present, cyanidin, or delphinidin. Flavonols present; kaempferol, or quercetin, or kaempferol and quercetin (mostly both). Ellagic acid absent (6 species, 3 genera). Aluminium accumulation demonstrated (rarely), or not found. Sugars transported as sugar alcohols + oligosaccharides + sucrose (in Escallonia, but depauperate in oligosaccharides).

Geography, cytology. Temperate to tropical. Tropical and South temperate, mostly South America and Australasia.

Taxonomy.Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Corniflorae; Cornales. Cronquist’s Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; campanulid; Order Escalloniales.

Species about 140. Genera 7; Anopterus, Cuttsia, Escallonia, Forgesia,Polyosma, Valdivia.

General remarks. Escalloniaceae are one of a few families that have long posed major difficulties of assignment, not only between (for example) Dahlgren’s Araliiflorae and Corniflorae, but also in terms of the higher level groupings Crassinucelli and Tenuinucelli, which evidently represent a major divergence in the Dicot line of descent (cf.Young and Watson 1970, Chase et al. 1993). Molecular sequencing studies place most of them firmly in the Tenuinucelli, but components appear in association with three of the major linages perceived therein (Backlund and Bremer, 1997). Adjustments to the present package await comprehensive reassignments, along with preparation of the requisite revised family descriptions.

 Illustrations:

  • Technical details: Escallonia.
  • Escallonia illinita: Bot. Reg. 1900 (1836).
  • Escallonia montevidensis: Bot. Reg. 1467, 1831.
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