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The families of flowering plants

L. Watson and M.J. Dallwitz

Chloranthaceae R. Br.

Habit and leaf form. Trees, shrubs, and herbs; bearing essential oils. Plants non-succulent. Annual, or perennial. Leaves opposite; petiolate; connate; aromatic; simple; epulvinate; stipulate. Stipules interpetiolar. Lamina margins serrate. Leaf development not ‘graminaceous’.

Leaf anatomy. The leaf lamina dorsiventral. Stomata mainly confined to one surface (abaxial); “surrounded by variousy arranged subsidiaries”. Adaxial hypodermis commonly present. Lamina with secretory cavities, or without secretory cavities. Secretory cavities when present, containing mucilage. The mesophyll with spherical etherial oil cells; without crystals. Minor leaf veins without phloem transfer cells (Chloranthus).

Axial (stem, wood) anatomy. Young stems usually cylindrical; with solid internodes. Secretory cavities present, or absent; when present, with mucilage. Nodes unilacunar (clearly, in Ascarina and Hedyosmum), or tri-lacunar (or interpretable as a modification of such, in other genera); exhibiting on either side a trace which divides, contributing the outermost lateral traces to each of the opposite leaves (e.g., in Chloranthus and Sarcandra), or without split-lateral traces. Primary vascular tissues in a cylinder, without separate bundles; collateral. Secondary thickening developing from a conventional cambial ring. The axial xylem with vessels, or without vessels.

The vessels small; solitary (often exclusively so), or solitary and radially paired, or solitary and in radial multiples. The vessel end-walls very oblique; scalariform. The axial xylem with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres; including septate fibres, or without septate fibres. The fibres without spiral thickening. The parenchyma apotracheal, or paratracheal; wood not storied.

Reproductive type, pollination. Plants hermaphrodite, or dioecious.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in spikes, or in heads, or in panicles. The ultimate inflorescence units cymose. Inflorescences terminal, or axillary; spikes or cymes. Flowers two bracteolate; small; ‘reduced’.

Perianth sepaline (female and hermaphrodite flowers), or absent (male flowers); when present, 3; when present, joined; when present, 1 whorled.

Androecium 1–5. Androecial members free of the perianth; united with the gynoecium; usually more than one, coherent; 1 adelphous (more or less connate). Androecium exclusively of fertile stamens, or including staminodes (or at least the laterals sometimes with only half-anthers). Stamens 1–3(–5); laminar, or filantherous. Anthers dehiscing via longitudinal slits, or dehiscing by longitudinal valves; unilocular to bilocular; tetrasporangiate, or bisporangiate and tetrasporangiate (in Chloranthus). Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral. Anther wall initially with more than one middle layer. Pollen grains aperturate, or nonaperturate; 1–6 aperturate; sulcate, or colpate, or porate; 2-celled.

Gynoecium when present, 1 carpelled. The pistil 1 celled. Gynoecium monomerous; of one carpel; superior, or partly inferior. Carpel 1 ovuled. Placentation apical. Stigmas dry type; non-papillate; Group II type. Ovules pendulous; anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle, or not contributing to the micropyle. Embryo-sac development Polygonum-type. Antipodal cells formed; initially 3; proliferating (sometimes, up to 40 cells), or not proliferating. Synergids pear-shaped. Endosperm formation cellular. Embryogeny onagrad, or chenopodiad.

Fruit fleshy. The fruiting carpel indehiscent; drupaceous. Seeds endospermic. Endosperm oily (and starchy). Perisperm present. Seeds with starch. Embryo rudimentary at the time of seed release to well differentiated (very small). Cotyledons when differentiated, 2.

Physiology, phytochemistry. Accumulated starch other than exclusively ‘pteridophyte type’. Proanthocyanidins absent. Flavonols absent. Ellagic acid absent (Chloranthus). Aluminium accumulation not found. Sieve-tube plastids S-type.

Geography, cytology. Sub-tropical to tropical. South and Central America, Southeast Asia and Malaysia. X = 8, 14, 15.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Magnoliiflorae; Magnoliales. Cronquist’s Subclass Magnoliidae; Piperales. APG III core angiosperms; unplaced at Superordinal level. APG IV Order Chloranthales.

Species 65. Genera 4; Ascarina, (Ascarinopsis), Chloranthus, Hedyosmum, Sarcandra.

General remarks. See Leroy 1983.

Illustrations. • Chloranthus angustifolius: Hook. Ic. Pl. 16 (1887). • Choranthus monostachys: Curtis, Bot. Mag. 48 (1821). • Le Maout and Decaisne: Chloranthus, Sarcandra.

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.’.