The Families of Flowering Plants
The Families of Flowering Plants |
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~ Saxifragaceae
Habit and leaf form. Erect, branched herbs. Plants non-succulent. Annual, or biennial (sometimes glandular); with neither basal nor terminal aggregations of leaves. Leaves opposite; not gland-dotted; simple. Lamina entire; linear to lanceolate, or ovate; attenuate at the base. Leaves exstipulate. Lamina margins entire.
Leaf anatomy. Lamina isobilateral, or centric.
Stem anatomy. Cork cambium present; initially superficial (in the epidermis). Cortical bundles absent. Medullary bundles absent. Internal phloem absent.
Reproductive type, pollination. Fertile flowers hermaphrodite. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes. The ultimate inflorescence unit cymose. Inflorescences terminal and axillary; sympodial, cymose, the flowers paired. Flowers regular; 5 merous; cyclic; tetracyclic. Free hypanthium absent.
Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous; regular; valvate. Corolla 5; 1 whorled; polypetalous (the petals shorter than the sepals); imbricate; regular; white, or yellow. Petals ovate-spathulate.
Androecium 5. Androecial members free of the perianth (inserted on the margin of the epigynous disk); all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; isomerous with the perianth; oppositisepalous; alternating with the corolla members; filantherous (the filaments subulate). Anthers dorsifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral. Tapetum glandular (?, the cells becoming binucleate). Pollen grains 2-celled.
Gynoecium 2–3 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium syncarpous; synovarious; inferior. Ovary 1 locular. Epigynous disk present (inconspicuous). Gynoecium stylate. Styles 2–3 (thick, divaricate); free; apical. Stigmas 2–3; dorsal to the carpels (according to Hutchinson); capitate. Placentation apical (with 2–3 remarkably large, pendulous, apical placentas). Ovules in the single cavity 50–200 (‘very numerous’); pendulous; anatropous; bitegmic; tenuinucellate. Outer integument not contributing to the micropyle. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; persistent. Synergids hooked. Endosperm formation cellular. Endosperm haustoria present; chalazal. Embryogeny caryophyllad.
Fruit non-fleshy; dehiscent; a capsule. Capsules apically 2–3 valvular. Fruit 50–200 seeded (‘very numerous’). Seeds minute; appendaged.
Physiology, biochemistry. Iridoids detected (S.R. Jensen, unpublished); ‘Route I’ type.
Geography, cytology. Paleotropical and Cape. Temperate to tropical. Tropical and South Africa to Northwest India.
Taxonomy. Subclass Dicotyledonae; Tenuinucelli (polypetalous, but iridoids present and ovules tenuinucellate). Dahlgren’s Superorder Rosiflorae; Saxifragales. Cronquist’s Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; lamiid; Order unassigned to Order.
Species 5. Genera 1; only genus, Bistella (Vahlia).
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’.