Philadelphaceae D. Don
~ Hydrangeaceae
Excluding Pterostemonaceae
Habit and leaf form. Small trees, or shrubs (or subshrubs). Leaves deciduous; opposite, or whorled; flat; petiolate; not gland-dotted; simple. Lamina entire; pinnately veined, or palmately veined. Leaves exstipulate. Lamina margins entire, or serrate, or dentate. Domatia recorded (Philadelphus); represented by hair tufts.
Leaf anatomy. Hairs present. Complex hairs present; usually stellate.
Lamina dorsiventral. Minor leaf veins without phloem transfer cells (Carpenteria, Philadelphus).
Stem anatomy. Secondary thickening developing from a conventional cambial ring. Wood parenchyma apotracheal (consisting of only a few scattered cells).
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’ (usually), or solitary (occasionally); when aggregated, in cymes, or in racemes, or in heads. Inflorescences terminal; terminal racemes, cymes or heads. Flowers medium-sized; fragrant (often), or odourless; regular. Free hypanthium absent.
Perianth with distinct calyx and corolla; (9–)10–12; 2 whorled; isomerous, or anisomerous. Calyx 4, or 5; 1 whorled; gamosepalous; blunt-lobed; regular; persistent; imbricate, or valvate. Epicalyx absent. Corolla 5–7; 1 whorled; polypetalous; imbricate, or contorted, or valvate; regular; usually white.
Androecium (4–)10–200 (to ‘many’, very numerous in Carpenteria). Androecial members branched (from a small number of primordia), or unbranched; when maturation sequence determinable, maturing centripetally; free of the perianth; free of one another, or coherent (sometimes basally connate). Androecium exclusively of fertile stamens. Stamens (4–)10–200 (i.e. to ‘many’); diplostemonous to polystemonous. Filaments appendiculate (sometimes lobed or toothed), or not appendiculate. Anthers dorsifixed to basifixed (mostly ‘almost basifixed’); versatile; dehiscing via longitudinal slits; almost latrorse (e.g. Whipplea), or introrse. Pollen grains aperturate; 3 aperturate; colporate (colporoidate); 2-celled.
Gynoecium (3–)5(–7) carpelled, or 1 carpelled (rarely). Carpels reduced in number relative to the perianth to increased in number relative to the perianth. The pistil (1–)5–7 celled. Gynoecium syncarpous; synovarious (usually, more or less), or synstylovarious; superior to inferior. Ovary (1–)5–7 locular; sessile. Gynoecium stylate. Styles (2–)5–7; free, or partially joined; apical. Stigmas dry type; papillate; Group II type (B(i)). Placentation when unilocular, apical; when plurilocular, axile (usually), or parietal (rarely). Ovules in the single cavity 1–50 (?); (1–)25–50 per locule (usually ‘many’); pendulous to ascending; anatropous; unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; persistent. Synergids pear-shaped. Endosperm formation cellular, or nuclear. Endosperm haustoria present (Deutzia, Philadelphus); micropylar.
Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal. Seeds endospermic; small; winged, or wingless. Embryo well differentiated (small). Cotyledons 2. Embryo achlorophyllous (2/7); straight.
Physiology, biochemistry. Not cyanogenic. Iridoids detected (in 7 Deutzia species); ‘Route I’ type (?). Proanthocyanidins present, or absent; when present, cyanidin. Flavonols present; quercetin, or kaempferol and quercetin. Ellagic acid absent (4 species, 3 genera). Ursolic acid absent. Sugars transported as oligosaccharides + sucrose (in Philadelphus). C3 (?), or CAM. CAM recorded directly in Philadelphus — Troughton et al. 1974.
Geography, cytology. Holarctic and Paleotropical. Temperate to sub-tropical. Southern Europe to Eastern Asia, North and Central America, Philippines.
Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Corniflorae; Cornales. Cronquist’s Subclass Rosidae; Rosales. APG (1998) Eudicot; core Eudicot; Asterid; unassigned to Euasterid I or Euasterid II; Cornales (as a synonym of Hydrangeaceae). Species 135. Genera 7; Carpenteria, Deutzia, Fendlera, Fendlerella, Jamesia, Philadelphus, Whipplea.
Illustrations. • Technical details (Philadelphus). • Technical details (Deutzia).
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).
