The families of flowering plants
Habit and leaf form. Small shrubs; bearing essential oils. Leaves persistent; small; alternate; leathery; shortly petiolate; non-sheathing; rather inconspicuously gland-dotted; aromatic, or without marked odour (? - the mesophyll cavities with oily or resinous contents); simple. Lamina entire; lanceolate to oblanceolate, or ovate to obovate; one-veined, or pinnately veined (?). Leaves exstipulate. Lamina margins entire.
Leaf anatomy. The leaf lamina dorsiventral. Stomata present; mainly confined to one surface and on both surfaces (fewer adaxially); anomocytic. Hairs present (often 2-armed, and multicelular glands also present); eglandular and glandular; unicellular, or multicellular (? - often T or Y shaped). The mesophyll with secretory cells having oily or resinous contents. Minor leaf veins without phloem transfer cells (Cneorum).
Axial (stem, wood) anatomy. Young stems with spongy internodes. Pith homogeneous (consisting of spongy parenchyma). Secretory cavities absent (but with secretory cells in the cortex). Primary vascular tissues in a cylinder, without separate bundles (traversed by narrow rays); collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow.
The wood diffuse porous, or ring porous to semi-ring porous. The vessels small; radially paired to in radial multiples, or clustered, or in tangential arcs. The vessel end-walls simple. The axial xylem with tracheids (dubiously), or without tracheids; without vasicentric tracheids; without fibre tracheids; with libriform fibres. The fibres without spiral thickening. The parenchyma predominantly paratracheal. The secondary phloem not stratified. Included phloem absent. The wood partially storied (VP), or not storied.
Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in inflorescences; when solitary, axillary; when aggregated, in cymes, or in corymbs. The ultimate inflorescence units cymose. Inflorescences axillary (the peduncle sometimes adnate to the petiole); small, few flowered axillary corymbs. Flowers small; regular; 3 merous (Cneorum), or 4 merous (Neochamaelea). Floral receptacle developing an androphore (this nectariferous, shortly columnar). Free hypanthium absent.
Perianth with distinct calyx and corolla; 6, or 8 (Neochamaelea); 2 whorled; isomerous. Calyx 3, or 4; 1 whorled; polysepalous, or gamosepalous (basally). Calyx lobes when gamosepalous, markedly longer than the tube. Calyx regular; persistent (small). Corolla polypetalous (the petals elongate); imbricate.
Androecium 3, or 4. Androecial members free of the perianth; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 3, or 4; isomerous with the perianth; oppositisepalous; alternating with the corolla members; filantherous (the filaments seated in pits in the androgynophore). Anthers dorsifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate, or 4–6 aperturate; colporate; 3-celled.
Gynoecium 3 carpelled, or 4 carpelled. Carpels isomerous with the perianth. The pistil 3 celled, or 4 celled, or 6 celled, or 8 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 3 locular, or 4 locular. Locules partially secondarily divided by false septa, or without false septa. Gynoecium stylate. Styles 1; apical. Placentation apical. Ovules (1–)2 per locule; pendulous; epitropous; with ventral raphe; collateral, or superposed (the two commonly more or less separated by an intrusion from the carpellary midrib); anatropous to amphitropous; bitegmic (the outer integument scarcely developed on the raphal side); crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating. Synergids pear-shaped. Endosperm formation nuclear. Embryogeny asterad.
Fruit fleshy, or non-fleshy; a schizocarp. Mericarps 3, or 4, or 6, or 8; comprising drupelets (the 12 seeded mericarps separating, and the fruit wall assuming the protective functions of the reduced testa). Seeds copiously endospermic. Endosperm oily. Embryo well differentiated. Cotyledons 2. Embryo achlorophyllous (1/1); strongly curved (in the curved seed).
Seedling. Germination phanerocotylar.
Physiology, phytochemistry. Not cyanogenic. Iridoids not detected. Proanthocyanidins absent. Flavonols present; kaempferol and quercetin. Ellagic acid absent (Cneorum).
Geography, cytology. Holarctic and Neotropical. Temperate (warm), sub-tropical to tropical. Cuba, Canaries, Mediterranean. X = 9.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Rutiflorae; Rutales. Cronquists Subclass Rosidae; Sapindales. APG III core angiosperms; core eudicot; Superorder Rosanae; malvid. APG IV Order Sapindales (as a synonym of Rutaceae).
Species 3. Genera 2; Cneorum, Neochamaelea.
General remarks. Seemingly differing from Rutaceae sensu stricto (q.v.) in the elongated torus (androphore?), apical placentation of the ovary, and obscure embryological details.
Illustrations. • Cneorum tricoccum and C. pulverentulum: Nat. Pflanzenfam., 3 (1896). • Cneorum pulverentulum: Hutchinson. • Le Maout and Decaisne: Cneorum.
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or 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 or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 15th April 2018. delta-intkey.com/angio’.