The families of flowering plants
Including Halesiaceae D. Don, Styraceae (Styracaceae) Spreng. (p.p.)
Habit and leaf form. Trees and shrubs; resinous. Normal plants. Leaves alternate; herbaceous, or leathery; petiolate; without marked odour; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire, or crenate, or serrate, or dentate.
Leaf anatomy. Stomata present; mainly confined to one surface (abaxial); anomocytic. Hairs present; multicellular. Complex hairs usually present (usually brown or rufous); peltate, or stellate.
Lamina dorsiventral. Minor leaf veins without phloem transfer cells (Styrax).
Stem anatomy. Secretory cavities present, or absent; when present, with resin. Cork cambium present; initially deep-seated. Nodes unilacunar. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. Xylem with fibre tracheids; with vessels. Vessel end-walls scalariform, or scalariform and simple. Wood parenchyma apotracheal (usually), or paratracheal (scanty and diffuse, rarely).
Reproductive type, pollination. Plants hermaphrodite (usually), or polygamomonoecious (Bruinsmia).
Inflorescence, floral, fruit and seed morphology. Flowers solitary (occasionally), or aggregated in inflorescences; in cymes, or in racemes, or in panicles. Inflorescences terminal, or axillary. Flowers ebracteolate; regular; cyclic; tetracyclic. Free hypanthium present, or absent.
Perianth with distinct calyx and corolla; (4–)8–10(–14); 2 whorled; isomerous. Calyx (2–)4–5(–7); 1 whorled; gamosepalous; entire, or lobulate, or blunt-lobed, or toothed; tubular; regular; persistent; valvate, or open in bud. Corolla (2–)4–5(–7); 1 whorled; not appendiculate; polypetalous (rarely, Bruinsmia, but often almost so), or gamopetalous (generally with the tube much shorter than the lobes, rarely (Halesia) these shorter than the tube). Corolla lobes markedly longer than the tube (usually), or markedly shorter than the tube (Halesia). Corolla imbricate, or valvate; not fleshy.
Androecium (5–)8–10(–20) (commonly twice as many as the corolla lobes, sometimes four times as many). Androecial members adnate (the filaments adnate to the corolla tube), or free of the perianth (rarely, attached directly to the receptacle); free of one another (rarely), or coherent (usually,below, into a short to long tube); usually 1 adelphous; 1 whorled. Androecium exclusively of fertile stamens. Stamens (5–)8–10(–20); isomerous with the perianth (Pamphilia), or diplostemonous to polystemonous (but all in one whorl); when 5, oppositisepalous. Anthers adnate; dehiscing via longitudinal slits; latrorse, or introrse; tetrasporangiate; appendaged (sometimes, the connective shortly prolonged), or unappendaged. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral. Anther wall of the dicot type. Tapetum glandular. Pollen grains aperturate; 3 aperturate; colporate (colpor(oid)ate, constricticolpate); 2-celled.
Gynoecium (2–)3–5 carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil (2–)3–5 celled. Gynoecium syncarpous; eu-syncarpous; superior to inferior. Ovary (2–)3–5 locular. Gynoecium stylate. Styles 1; apical. Stigmas 1 (capitate or merely lobed). Placentation axile. Ovules (1–)4–6(–50) per locule; pendulous to ascending; sometimes with an obturator; anatropous, or hemianatropous; unitegmic (Halesia), or bitegmic (Styrax); tenuinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing only after one has been fertilized. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids elongated. Endosperm formation cellular. Embryogeny solanad.
Fruit fleshy (rarely), or non-fleshy; dehiscent, or indehiscent; a capsule, or capsular-indehiscent, or a drupe (rarely), or a samara; one- or few-seeded. Seeds endospermic. Endosperm oily. Seeds winged (Alniphyllum), or wingless. Embryo well differentiated. Cotyledons 2; flat (broad). Embryo achlorophyllous (2/2); slightly curved, or straight.
Seedling. Germination phanerocotylar.
Physiology, biochemistry. Not cyanogenic. Alkaloids absent (3 species). Iridoids not detected. Proanthocyanidins present, or absent; cyanidin. Flavonols present; kaempferol and quercetin. Ellagic acid absent (2 genera, 2 species). Saponins/sapogenins present. Aluminium accumulation not found. Sugars transported as sugar alcohols + oligosaccharides + sucrose (in Styrax, but sucrose predominating).
Geography, cytology. Temperate (warm), or sub-tropical to tropical. Eastern Asia to Western Malaysia, Mediterranean, Southeast U.S.A., Mexico to tropical South America. X = 8, 12.
Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgrens Superorder Primuliflorae; Ebenales. Cronquists Subclass Dilleniidae; Ebenales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; Order Ericales.
Species 180. Genera 11; Alniphyllum, Bruinsmia, Halesia, Huodendron, Melliodendron, Pamphilia, Parastyrax, Pterostyrax, Rehderodendron, Sinojackia, Styrax.
Illustrations. • Technical details: Styrax. • Technical details: Styrax, Halesia (Lindley). • Halesia cardina: Bot. Reg. 952, 1825.
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using 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).
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 December 2012. http://delta-intkey.com’.