The Families of Flowering Plants
The Families of Flowering Plants | |
Habit and leaf form. Shrubs; bearing essential oils. Leaves small; alternate; distichous; petiolate; gland-dotted; simple. Lamina entire; obovate (emarginate); pinnately veined. Leaves stipulate. Stipules intrapetiolar (adnate to the petiole, large, sheathing); membranous; persistent. Lamina margins entire.
Leaf anatomy. Stomata present; anomocytic.
The mesophyll with spherical etherial oil cells.
Stem anatomy. Nodes unilacunar (with two traces). Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem with fibre tracheids; with libriform fibres. Vessel end-walls horizontal; simple. Primary medullary rays wide (and high). Wood parenchyma diffuse to apotracheal. Sieve-tube plastids S-type.
Reproductive type, pollination. Plants polygamodioecious.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when solitary, axillary; when aggregated, in cymes. The terminal inflorescence unit cymose. Inflorescences axillary; monochasia. Flowers small; 3 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent.
Perianth sepaline; 3; 1 whorled. Calyx 3; 1 whorled; polysepalous; imbricate.
Androecium 6. Androecial members free of the perianth; free of one another; 2 whorled. Androecium exclusively of fertile stamens, or including staminodes (in some flowers). Staminodes when present, 3; internal to the fertile stamens (the members of the inner androecial whorl); non-petaloid. Stamens 6; diplostemonous; alternisepalous (according to Hutchinson’s illustration); narrowly laminar (short). Anthers adnate; non-versatile; dehiscing via longitudinal slits; extrorse; bilocular (the sporangia well separated, nearly marginal, almost as long as the blade); tetrasporangiate; shortly appendaged (by a short prolongation of the connective). The anther appendages apical. Pollen shed in aggregates; in tetrads. Pollen grains aperturate; obscurely 1 aperturate; sulcate, or ulcerate (the aperture poorly defined).
Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled (basally). Gynoecium apocarpous to syncarpous; semicarpous (the carpels in a single whorl, medially more or less connate at the base); superior. Carpel shortly stylate; with a decurrent stigma; (4–)6(–8) ovuled. Placentation marginal (the placenta intruded). Ovary basally 3 locular. Ovules long funicled; biseriate; anatropous; bitegmic; weakly crassinucellate. Endosperm formation nuclear.
Fruit non-fleshy; an aggregate. The fruiting carpels coalescing into a secondary syncarp. The fruiting carpel dehiscent; a follicle. Seeds endospermic. Endosperm oily. Embryo well differentiated (very small). Cotyledons 2.
Physiology, biochemistry. Saponins/sapogenins absent. Aluminium accumulation not found.
Geography, cytology. Neotropical. Juan Fernandez. X = 40, 42.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Magnoliiflorae; Magnoliales. Cronquist’s Subclass Magnoliidae; Magnoliales. APG (1998) basal order; Piperales. Species 1. Genera 1; only genus, Lactoris.
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: 10th April 2008. http://delta-intkey.com’.