The Families of Flowering Plants
The Families of Flowering Plants |
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~ 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. • Technical details: Deutzia (Lindley). • Technical details: Philadelphus. • Deutzia corymbosa: Bot. Reg. xxvi, 5 (1840). • Deutzia scabra: Bot. Reg. 1718, 1835. • Philadelphus coronarius: Bot. Mag. 391, 1797. • Philadelphus coronarius: Bot. Mag. 391, text. • Philadelphus gordonianus: Bot. Reg. 1839, 32. • Philadelphus hirsutus: Bot. Reg. XXIV, 14, 1838. • Philadelphus mexicanus: Bot. Reg. 38, 1842. • Philadelphus speciosus, = ?: Bot. Reg. 2003, 1837.
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 specified attributes, summaries of attributes within groups of taxa, geographical distribution, genera included in each family, classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG), and notes on the APG classification.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 25th November 2009. http://delta-intkey.com’.
