Family Myristicaceae

Myristicaceae R. Br.

Habit and leaf form. Trees; with coloured juice (typically with red sap); bearing essential oils. Mesophytic. Leaves evergreen; 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. Leaves without a persistent basal meristem. Vernation conduplicate.

Leaf anatomy. Stomata paracytic.

Lamina usually with secretory cavities. Secretory cavities containing oil. The mesophyll with spherical etherial oil cells; with sclerencymatous idioblasts, or without sclerenchymatous idioblasts.

Stem anatomy. Cork cambium present; initially superficial. Nodes bilacunar (but with three traces, according to Lammers et al. 1986), or unilacunar (?). Internal phloem absent. Secondary thickening developing from a conventional cambial ring. The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones, or not stratified. ‘Included’ phloem absent. Xylem with libriform fibres. Vessel end-walls scalariform, simple, and reticulately perforated. Vessels without vestured pits. Wood parenchyma mainly paratracheal (scanty to almost vasicentric). Sieve-tube plastids S-type. Pith with diaphragms, or without diaphragms.

Reproductive type, pollination. 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 unit 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, biochemistry. Not cyanogenic. Alkaloids present, or absent. Iridoids not detected. Proanthocyanidins present; cyanidin. Flavonols present; kaempferol and quercetin. Ellagic acid absent (Myristica).

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

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Magnoliiflorae; Annonales. Cronquist’s Subclass Magnoliidae; Magnoliales. APG 3 core angiosperms; Superorder Magnolianae; Order Magnoliales.

Species 300. Genera 19; Bicniba, 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.
• Technical details: Ambora (= Tambourissa), Myristica.
• Myristica: fruit, embryo, androecium.