Family Philadelphaceae
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 occurring in the family (Philadelphus); manifested as 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 (these few-flowered, in some Philadelphus spp.), or in racemes (ostensibly), or in heads, or in panicles. The ultimate inflorescence unit seemingly essentially cymose. Inflorescences terminal. Flowers medium-sized; fragrant (often), or odourless; regular. Free hypanthium absent. Perianth with distinct calyx and corolla; (8–)10–12; 2 whorled; isomerous, or anisomerous. Calyx 4, or 5–6; 1 whorled; gamosepalous; blunt-lobed; regular; persistent; imbricate, or valvate. Corolla 4 (commonly so, in Philadelphus), or 5–6; 1 whorled; polypetalous; imbricate, or contorted (e.g., in Philadelphus), 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 (in Deutzia, Jamesia and Philadelphus). Gynoecium (3–)4 carpelled, or 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–)4 celled, or 5–7 celled. Gynoecium syncarpous; synovarious (usually, more or less), or synstylovarious; superior to inferior. Ovary (1–)4 locular, or 5–7 locular; sessile. Gynoecium stylate. Styles (2–)4 (commonly in Philadelphus), or 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, or valvular (e.g., in Philadelphus, Carpenteria). 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 3 core angiosperms; core eudicot; Superorder Asteranae; Order Cornales (as a synonym of Hydrangeaceae). Species 135. Genera 7; Carpenteria, Deutzia, Fendlera, Fendlerella, Jamesia, Philadelphus, Whipplea. Thanks to Mike Hackston (June 2007) for correcting an error in an earlier version of this description. Illustrations. |
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