Family Chloranthaceae

Chloranthaceae R. Br.

Habit and leaf form. Trees, shrubs, and herbs; bearing essential oils. Annual, or perennial. Leaves opposite; petiolate; connate; aromatic; simple; epulvinate; stipulate. Stipules interpetiolar. Lamina margins serrate. Leaves without a persistent basal meristem.

General anatomy. Accumulated starch other than exclusively ‘pteridophyte type’.

Leaf anatomy. Adaxial hypodermis commonly present. Lamina dorsiventral; with secretory cavities, or without secretory cavities. Secretory cavities when present, containing mucilage. The mesophyll with spherical etherial oil cells; without calcium oxalate crystals. Minor leaf veins without phloem transfer cells (Chloranthus).

Stem anatomy. Stems with solid internodes. Young stems usually cylindrical. Secretory cavities present, or absent; when present, with mucilage. Nodes unilacunar (clearly, in some genera), or tri-lacunar (or interpretable as a modification of such, in some genera). Secondary thickening developing from a conventional cambial ring. Xylem with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres; with vessels, or without vessels. Vessel end-walls oblique; scalariform. Wood parenchyma paratracheal. Sieve-tube plastids S-type.

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 unit 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, biochemistry. Proanthocyanidins absent. Flavonols absent. Ellagic acid absent (Chloranthus). Aluminium accumulation not found.

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 3 core angiosperms; unplaced at Superordinal level; Order Chloranthales.

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

Leroy 1983.

Illustrations.
• Technical details: Chloranthus, Sarcandra.