The Families of Angiosperms

L. Watson and M.J.Dallwitz

Nyssaceae Dum.

~Cornaceae p.p.

Habit and leaf form.Trees(mostly), or shrubs.Plantsgreen and photosynthesizing.Leaves persistent; alternate; petiolate; non-sheathing;without markedodour; simple. Lamina entire; pinnately veined; cross-venulate.Leavesexstipulate. Lamina margins entire, or dentate. Domatiaoccurring in the family; manifested as pockets.

Leaf anatomy.The leaflamina dorsiventral (with a single palisade layer). Mucilaginous epidermispresent. Stomata present; mainly confined to one surface (abaxial); at least inNyssa, paracytic. Hairs present; glandular, or eglandular and glandular(? - not of the unicellular and 2–armed type common inCornaceae,the glandular hairs unicellular).The mesophyllwith sclerenchymatousidioblasts (these traversing the width of the lamina); containing crystals.The crystals druses (only, inNyssa), or druses and solitary-prismatic(Camptotheca). Main veins vertically transcurrent (via thin walledparenchyma).

Axial (stem, wood) anatomy.Pithwith diaphragms. Secretory cavities absent. Cork cambium present; initiallysuperficial (where observed, inNyssa). Nodes tri-lacunar. Primaryvascular tissues in a cylinder, without separate bundles; collateral. Internalphloem absent. Cortical bundles absent. Medullary bundles absent. Secondarythickening developing from a conventional cambial ring. Primary medullary raysnarrow.

The wood diffuse porous. The vessels small; solitary, radially paired, and inradial multiples (the latter short). The vessel end-walls oblique; scalariform.The vessels without vestured pits; with spiral thickening, or without spiralthickening. The axial xylem with fibre tracheids; with libriform fibres, orwithout libriform fibres; without septate fibres. The fibres without spiralthickening. The parenchyma apotracheal. The secondary phloem not stratified.‘Included’ phloem absent. The wood not storied.

Reproductive type, pollination.Unisexual flowers present.Plantsmonoecious, or dioecious,or polygamomonoecious (?).

Inflorescence, floral, fruit and seedmorphology.Flowers solitary, or aggregated in‘inflorescences’; when aggregated, in racemes, or in heads, or inumbels. The ultimate inflorescence units racemose. Inflorescences pedunculateheads, short racemes or compact umbels, or sometimes reduced to a single flower.Flowers small; regular, or somewhat irregular; cyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla (more or less), or sepaline(the calyx sometimes virtually obsolete); 5, or 10(–15); isomerous, oranisomerous.Calyx minutely 5 (toothed, or reduced to an irregularlytoothed rim); when pronounced, slightly gamosepalous; entire, or lobulate, orblunt-lobed, or toothed; unequal but not bilabiate, or regular;open inbud. Corolla (4–)5(–8); polypetalous (the petals small); more orless valvate (Camptotheca), or imbricate; regular.

Androecium in staminate and hermaphrodite flowers(8–)10(–16).Androecial members free of the perianth; free ofone another;2(–3) whorled. Androecium exclusively of fertilestamens, or including staminodes (some of the members sometimes imperfect inhermaphrodite flowers). Stamens (8–)10(–15); isomerous with theperianth to diplostemonous; alternisepalous (in male flowers), oroppositisepalous (in hermaphrodite flowers); filantherous (the filamentselongate-subulate, the anthers small).Anthersbasifixed;dehiscing via longitudinal slits; latrorse, or introrse; tetrasporangiate.Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate;2-celled.

Gynoecium(1–)2 carpelled. Carpels reduced innumber relative to the perianth. The pistil 1 celled, or 2 celled.Gynoecium syncarpous (but sometimes pseudomonomerous);synovarious tosynstylovarious;inferior. Ovary 1 locular, or 2 locular (sometimes,inNyssa). Epigynous disk present (large, pulviniform). Gynoeciumstylate. Styles 1–2; partially joined; apical. Stigmas 1–2.Placentation when pseudomenomerous, parietal to apical; when bilocular, axile toapical.Ovulespendulous; epitropous; with ventral raphe;anatropous; unitegmic; tenuinucellate to crassinucellate. Endotheliumdifferentiated. Endosperm formation cellular.

Fruit fleshy; indehiscent;a drupe, or a samara (obovate,compressed, drupaceous to subsamaroid). The drupes with one stone(1–2-loculed, these each opening apically by a triangular, apical-adaxialvalve on germination). Fruit 1 seeded. Seeds fairly copiously endospermic.Endosperm oily (and also with hemicellulose). Embryo well differentiated (andrather large). Cotyledons 2. Embryo straight.

Seedling.Germinationphanerocotylar.

Physiology, phytochemistry.Sugarstransported as sucrose. Not cyanogenic. Alkaloids present (Camptotheca),or absent (3 species). Iridoids detected; ‘Route I’ type (+seco).Proanthocyanidins absent. Ellagic acid present. Aluminium accumulation not found(but accumulating cobalt).

Geography, cytology.Holarctic.Temperate to tropical. Southeast and Eastern Asia, Eastern U.S.A.X = 21,22.

Taxonomy.Subclass Dicotyledonae;Tenuinucelli. Dahlgren’s Superorder Corniflorae; Cornales. Cronquist’sSubclass Rosidae; Cornales. APG III core angiosperms; core eudicot; SuperorderAsteranae. APG IV Order Cornales (as a synonym ofCornaceae).

Species 10. Genera 2;Camptotheca,Nyssa.

General remarks.See Eyde (1988).Differing fromCornaceae in the racemose inflorescences, more numerousstamens and epitropous ovules, and with the compiled data offering assorteddifferences in leaf and stem anatomy as well.

Illustrations.• Camptotheca acuminata: Das Pflanzenreich 220(1910). • Nyssa multiflora and N.ogeche: Nat Pflanzenfam. III. • Nyssa sinensis: Hook. Ic. Pl. 20 (1891).• Leaf TS and epidermis of Nyssacaroliniana and Camptotheca acuminata, with foliar trichomes of Cornus(Cornaceae), Corokia (Argophyllaceae) and Marlea (= Alangium, Alangiaceae):Solereder, 1908.

We advise against extracting comparative informationfrom the descriptions. This is much more easily achieved using theDELTA data files or theinteractive key, which allows access to the characterlist, illustrations, full and partial descriptions, diagnostic descriptions,differences and similarities between taxa, lists of taxa exhibiting or lackingspecified 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 alsoGuidelines for using data taken from Web publications.