Helwingiaceae Decaisne

~Cornaceae.

Habit and leaf form.Glabrousshrubs.Plantsgreen and photosynthesizing.Leavesalternate (to subopposite); spiral;very thinly‘herbaceous’; petiolate; simple. Lamina entire; ovatelanceolate, or ovate; pinnately veined; cross-venulate.Leavesstipulate (the stipules often branched). Stipules intrapetiolar (on thepetiole); free of one another; caducous. Lamina margins serrate (serrulate).

General anatomy.Plants without‘crystal sand’.

Leaf anatomy.The leaflamina dorsiventral (but the palisade scarcely differentiated). Stomatapresent; mainly confined to one surface (abaxial); anomocytic. Hairs absent(leaves glabrous). Lamina without secretory cavities. The mesophyll withoutcrystals. Main veins embedded. Minor leaf veins without phloem transfer cells.

Axial (stem, wood) anatomy.Secretory cavities absent. Nodes unilacunar. Primary vascular tissuesin a cylinder, without separate bundles; collateral. Internal phloem absent.Cortical bundles absent. Medullary bundles absent. Secondary thickeningdeveloping from a conventional cambial ring. Primary medullary rays narrow.

The wood diffuse porous. The vessel end-walls scalariform. The axial xylemwithout fibre tracheids; with libriform fibres; including septate fibres (afew), or without septate fibres. The parenchyma apotracheal.‘Included’ phloem absent. The wood not storied.

Reproductive type, pollination.Unisexual flowers present.Plantsdioecious.

Inflorescence, floral, fruit and seedmorphology.Flowers aggregated in ‘inflorescences’; inumbels.Inflorescences epiphyllous (from the upper side of the midrib);small epiphyllous umbels, the male flowers sometimes long pedicellate, thefemales shortly so. Flowers small; regular; 3–4(–5) merous;cyclic. Free hypanthium absent.

Perianthpetaline (as described by Airy Shaw);3–4(–5); 1 whorled. Corolla 3–4(–5); 1 whorled;polypetalous; valvate.

Androecium 3–4(–5). Androecial members free of theperianth; free of one another; 1 whorled. Androecium of male flowers,exclusively of fertile stamens. Stamens 3–4(–5); isomerous with theperianth; (theoretically) oppositisepalous; alternating with the corollamembers; filantherous (inserted outside the flat angled disk). Anthers dehiscingvia longitudinal slits; introrse. Pollen grains aperturate; 3 aperturate;colporate.

Gynoecium 3–4 carpelled. Carpels reduced in number relative tothe perianth to isomerous with the perianth. The pistil 3–4 celled.Gynoecium syncarpous; synstylovarious;inferior.Ovary3–4 locular. Epigynous disk present (passing into the style).Gynoecium stylate.Styles1; apical; shorter than the ovary.Stigmas 3–4 (recurved).Placentationapical. Ovules 1 perlocule; pendulous; apotropous; with dorsal raphe; anatropous.

Fruit fleshy; indehiscent; a drupe. The drupes with separable pyrenes(3–4). Fruit 3–4 seeded. Seeds endospermic. Embryo welldifferentiated (small). Embryo straight.

Physiology, phytochemistry.Iridoids not detected.

Geography, cytology.Holarctic.Temperate. Eastern Himalayas to Japan and Formosa.X = 19.

Taxonomy.Subclass Dicotyledonae;Tenuinucelli (?). Dahlgren’s Superorder Araliiflorae; Araliales.Cronquist’s Subclass Rosidae; Cornales. APG III core angiosperms; coreeudicot; Superorder Asteranae; campanulid. APG IV Order Aquifoliales.

Species 5. Genera 1; only genus,Helwingia.

Illustrations.• Helwingia cf. japonica (as rusciflora): Nat.Pflanzenfam. III (1898). • Helwingia cf. japonica, as H. ruscifolia:Lindley. • Helwingia cf.japonica, as H. rusciflora: Le Maout and Decaisne.

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.