| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Myristicaceae R. Br.

Habit and leaf form. Trees; with coloured juice (typically with red sap); bearing essential oils. Mesophytic. Leaves persistent; alternate; spiral to distichous; leathery; petiolate; non-sheathing; gland-dotted (often), or not gland-dotted; aromatic (often), or without marked odour; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire. Leaf development not ‘graminaceous’. Vernation conduplicate.

Leaf anatomy. Stomata where observed, paracytic. Hairs present (in considerable diversity, but mostly interpretable as interpretable as uniseriate, sympodially branched trichomes: see illustration); seemingly all eglandular; multicellular. Multicellular hairs uniseriate; branched. Complex hairs absent. Lamina usually with secretory cavities. Secretory cavities containing oil. The mesophyll with spherical etherial oil cells (at least, usually with spherical secretory cells having yellow, red or brown, liquid or crystalline contents); with sclerenchymatous idioblasts, or without sclerenchymatous idioblasts; containing crystals. The crystals solitary-prismatic (typically acicular), or druses and solitary-prismatic.

Axial (stem, wood) anatomy. Pith with diaphragms, or without diaphragms. Cork cambium present; initially superficial. Nodes unilacunar (with three traces), or bilacunar (? - according to Lammers et al. 1986). Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent (at least from vegetative axes, though sometimes found in leaves and peduncles). Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow.

The wood diffuse porous. The vessels in different genera small, or medium, or large; solitary, radially paired, and in radial multiples (of few cells). The vessel end-walls often mixed reticulately perforated, scalariform, and simple. The vessels without vestured pits; without spiral thickening. The axial xylem without fibre tracheids; with libriform fibres (sometimes with small borders); including septate fibres (rarely), or without septate fibres. The fibres without spiral thickening. The parenchyma mainly paratracheal (scanty to almost vasicentric). The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones, or not stratified. ‘Included’ phloem absent. The wood not storied.

Reproductive type, pollination. Unisexual flowers present. Plants monoecious, or dioecious. Female flowers without staminodes. Gynoecium of male flowers absent.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes, in fascicles, in racemes, and in heads. The ultimate inflorescence units cymose, or racemose. Inflorescences axillary. Flowers bracteate (the bract usually solitary, small); small; usually 3 merous; cyclic.

Perianth sepaline; (2–)3(–5); joined; 1 whorled. Calyx (the perianth being thus interpreted) (2–)3(–5); 1 whorled; gamosepalous; blunt-lobed; valvate.

Androecium (2–)3–30. Androecial members branched, or unbranched (?); free of the perianth; coherent; 1 adelphous (the filaments united into a column); 1 whorled. Androecium exclusively of fertile stamens. Stamens (2–)3–30; isomerous with the perianth to polystemonous. Anthers cohering (laterally connate), or separate from one another; dehiscing via longitudinal slits; extrorse; tetrasporangiate. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads isobilateral. Anther wall initially with more than one middle layer (2). Tapetum glandular. Pollen shed as single grains. Pollen grains aperturate, or nonaperturate; when aperturate, 1 aperturate; sulcate, or ulcerate (?); 2-celled.

Gynoecium 1 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium monomerous; of one carpel; superior. Carpel incompletely closed; non-stylate, or stylate (subsessile); apically stigmatic; 1 ovuled. Placentation basal. Ovules arillate; anatropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Endosperm formation nuclear.

Fruit fleshy to non-fleshy (fleshy to leathery). The fruiting carpel usually dehiscent; a legume (i.e. from a single carpel, dehiscing along both sutures—or a ‘dehiscent berry’!). Fruit 1 seeded. Seeds endospermic. Endosperm ruminate; usually oily. Embryo well differentiated (very small). Cotyledons 2 (sometimes basally connate). Embryo achlorophyllous (2/4); straight.

Seedling. Germination cryptocotylar.

Physiology, phytochemistry. Not cyanogenic. Alkaloids present, or absent. Iridoids not detected. Proanthocyanidins present; cyanidin. Flavonols present; kaempferol and quercetin. Ellagic acid absent (Myristica). Sieve-tube plastids S-type.

Geography, cytology. Tropical. Pantropical. X = 9, 21, 25.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Magnoliiflorae; Annonales. Cronquist’s Subclass Magnoliidae; Magnoliales. APG III core angiosperms; Superorder Magnolianae. APG IV Order Magnoliales.

Species 300. Genera 19; Bicuiba, Brochoneura, Cephalosphaera, Coelocaryon, Compsoneura, Endocomia, Gymnacranthera, Haematodendron, Horsfieldia, Iryanthera, Knema, Mauloutchia, Myristica, Osteophloeum, Otoba, Pycnanthus, Scyphocephalium, Staudtia, Virola.

Economic uses, etc. Myristica fragrans supplies the spices nutmeg (the seed), and mace (dried arils).

Illustrations. • Le Maout and Decaisne: Ambora (= Tambourissa), Myristica. • Horsfieldia irya: Sinclaire, Gardens Bull. Singapore 16 (1958). • Horsfieldia glabra: Das, Ann. Roy. Bot. Gard. Calcutta 3 (1891). • Knema hookeriana: Sinclaire, Gardens Bull. Singapore 16 (1958). • Knema laterica: Sinclaire, Gardens Bull. Singapore 16 (1958). • Myristica fragrans: Hutchinson. • Le Maout and Decaisne: Myristica - fruit, embryo, androecium. • Myristica fragrans: Köhler’s Medizinal-Pflanzen 2 (1890). • Pycnanthus angolensis (as Myristica microcephalla) and Scyphocephalium ochocoa (as Myristica mannii): Hook. Ic. Pl. 13 (1877–79). • Leaf hairs of Dialyanthera (Otoba), Knema, Myristica and Virola: Solereder, 1908).

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: 8th June 2026. delta-intkey.com’.

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