Myrtaceae Juss.
Including Chamaelauciaceae Lindl., Kaniaceae Nakai, Leptospermaceae Kausel, Myrrhinieae (Myrrhiniaceae) Arn.
Excluding Heteropyxidaceae, Psiloxylaceae
Habit and leaf form. Trees and shrubs; bearing essential oils; leptocaul. Helophytic to xerophytic. Heterophyllous (sometimes markedly so, e.g Eucalyptus spp.), or not heterophyllous. Leaves evergreen (nearly always), or deciduous (e.g. some Eucalyptus species); small to large; opposite (commonly), or alternate, or whorled; ‘herbaceous’, or leathery; petiolate, or subsessile, or sessile, or perfoliate; connate (sometimes, in Eucalyptus), or not connate; gland-dotted; aromatic; edgewise to the stem (commonly, in Eucalyptus, Callistemon etc.), or with ‘normal’ orientation; simple; epulvinate. Lamina entire; linear, or lanceolate, or oblong, or ovate; pinnately veined, or parallel-veined, or one-veined. Leaves exstipulate (nearly always), or stipulate (e.g. Calythrix); without a persistent basal meristem.
Leaf anatomy. Mucilaginous epidermis present, or absent. Stomata mainly confined to one surface, or on both surfaces (commonly, in edgewise-orientated leaves); anomocytic (usually), or paracytic.
Lamina dorsiventral, or isobilateral, or dorsiventral and isobilateral (e.g. Eucalyptus, Eugenia species with vertical isobilateral leaves and horizontal dorsiventral leaves), or centric; with secretory cavities. Secretory cavities containing oil. Minor leaf veins without phloem transfer cells (6 genera).
Stem anatomy. Cork cambium present; initially deep-seated, or superficial. Nodes ‘typically’ unilacunar. Primary vascular tissue commonly bicollateral. Internal phloem present. Secondary thickening developing from a conventional cambial ring. The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones (usually), or not stratified (e.g. Darwinia, Verticordia). ‘Included’ phloem absent. Xylem with tracheids, or without tracheids; with fibre tracheids, or without fibre tracheids; with vessels. Vessel end-walls simple (usually), or scalariform. Vessels with vestured pits. Wood parenchyma apotracheal, or paratracheal, or apotracheal and paratracheal.
Reproductive type, pollination. Plants hermaphrodite (usually), or polygamomonoecious, or androdioecious (rarely). Entomophilous, or ornithophilous. Pollination mechanism conspicuously specialized (Chamelaucium and some relatives, with pollen presentation via a modified part of the style), or unspecialized (mostly).
Inflorescence, floral, fruit and seed morphology. Flowers solitary (rarely), or aggregated in ‘inflorescences’ (usually); in cymes, in spikes, in corymbs, and in panicles, or in heads (notably daisylike in Actinodium). The terminal inflorescence unit usually cymose. Inflorescences terminal, or axillary, or intercalary (often); spikes, cymes, corymbs, panicles, even heads; with involucral bracts, or without involucral bracts; pseudanthial, or not pseudanthial. Flowers often 2 bracteolate; calyptrate (notably in Eucalyptus), or not calyptrate; regular, or somewhat irregular. The floral irregularity (when noticeable) involving the androecium. Flowers cyclic. Free hypanthium present (petals ‘inserted on the calyx’). Hypogynous disk present (lining the hypanthium, when perigynous).
Perianth with distinct calyx and corolla (but these sometimes adnate to one another and constituting an operculum, which is shed at anthesis), or petaline (in Eucalyptus, where the connate ‘petals’ sometimes form the operculum alone), or sepaline (e.g. Osbornia); 4–11; 1 whorled, or 2 whorled; isomerous, or anisomerous. Calyx (3–)4–5(–6) (or vestigial); 1 whorled; polysepalous, or gamosepalous (then sometimes splitting irregularly at anthesis, or shed entire); regular; calyptrate, or not calyptrate; imbricate (usually quincuncial), or valvate (or splitting irregularly). Corolla 4–5; 1 whorled; polypetalous (the petals often almost circular when flattened), or gamopetalous; calyptrate, or not calyptrate; imbricate; regular; white, or yellow, or red, or pink, or purple (not blue).
Androecium 4–5 (rarely), or 8–10 (sometimes), or 20–150 (usually, ‘many’). Androecial members branched, or unbranched; when ‘many’, maturing centripetally; free of the perianth; all equal, or markedly unequal; free of one another, or coherent; when united, 1 adelphous (connate into a short tube), or 4–5 adelphous; when ‘definite’, 2 whorled. The androecial bundles when bundled, alternating with the corolla members, or opposite the corolla members. Androecium exclusively of fertile stamens, or including staminodes (sometimes, when A indefinite). Stamens (4–)10–150; isomerous with the perianth (rarely), or diplostemonous (sometimes), or triplostemonous to polystemonous (usually); erect in bud, or inflexed in bud (or twice folded). Filaments appendiculate (those of Corynanthera having a stipitate appendage around the level of the anther, perhaps representing the fourth sporangium of the trisporangiate anther), or not appendiculate (usually). Anthers dorsifixed; versatile; dehiscing via longitudinal slits, or dehiscing via pores (rarely); introrse; bilocular (mostly), or unilocular (e.g. Corynanthera); mostly tetrasporangiate (but trisporangiate in Corynanthera, and occasionally unisporangiate in Malleostemon); appendaged (often tipped by a gland), or unappendaged. Endothecium developing fibrous thickenings. Anther epidermis degenerating. Anther wall initially with one middle layer, or initially with more than one middle layer (1 or 2). Tapetum glandular. Pollen grains aperturate; (2–)3(–4) aperturate; colpate (seldom), or colporate (commonly), or porate (sometimes syncolpate); 2-celled.
Gynoecium 2–5(–16) carpelled. The pistil (1–)2–5(–16) celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; inferior (usually, more or less), or partly inferior (to varying degrees, rarely ‘almost superior’). Ovary (1–)2–5(–16) locular. Epigynous disk present, or absent (when perigynous). Gynoecium stylate. Styles 1; apical. Stigmas 1. Placentation when unilocular, parietal (on intrusive placentas, e.g. Feijoa); axile. Ovules in the single cavity 30–150 (‘many’); 2–50 per locule (i.e. to ‘many’); ascending; non-arillate; hemianatropous to anatropous; usually bitegmic; crassinucellate. Outer integument contributing to the micropyle, or not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization (usually), or fusing only after one has been fertilized (e.g. in Myrtus, Syzygium). Antipodal cells formed, or not formed (then the three nuclei degenerating early); when formed, 3; not proliferating; very ephemeral. Synergids pear-shaped, or hooked (commonly, and sometimes with filiform apparatus). Endosperm formation nuclear. Embryogeny onagrad (or adventive).
Fruit fleshy, or non-fleshy; dehiscent, or indehiscent; a capsule, or a berry, or a drupe, or a nut. Capsules septicidal, or loculicidal, or denticidal, or circumscissile (becoming operculate by removal of the epigynous disk). Seeds non-endospermic; winged (e.g. in some Eucalyptus), or wingless. Cotyledons 2. Embryo chlorophyllous (3 Eugenia species), or achlorophyllous (4/4); straight, or bent, or other than straight, curved, bent or coiled (sometimes spiral). Polyembryony commonly recorded.
Seedling. Germination phanerocotylar, or cryptocotylar.
Physiology, biochemistry. Cyanogenic, or not cyanogenic (usually). Cynogenic constituents phenylalanine-derived. Alkaloids present (rarely), or absent. Iridoids not detected. Proanthocyanidins present; cyanidin and delphinidin (usually), or cyanidin. Flavonols present; kaempferol, or kaempferol and quercetin, or quercetin and myricetin, or kaempferol, quercetin, and myricetin. Ellagic acid present (9 species, 7 genera), or absent (4 species, 4 genera). Ursolic acid present. Saponins/sapogenins present, or absent (mostly). Aluminium accumulation not found. Sugars transported as sucrose (in Syzygium), or as oligosaccharides + sucrose (mostly), or as sugar alcohols + oligosaccharides + sucrose (occasionally). Inulin recorded (Eucalyptus, Gibbs 1974). C3. C3 physiology recorded directly in Eucalyptus, Metrosideros. Anatomy non-C4 type (Eugenia, Leptospermum, Psidium).
Geography, cytology. Temperate, sub-tropical, and tropical. Widespread warm, chiefly centred in Australia and tropical America. X = (6-)11(-12).
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Myrtiflorae; Myrtales. Cronquist’s Subclass Rosidae; Myrtales. APG (1998) Eudicot; core Eudicot; Rosid; Eurosid II; Myrtales. Species 3000. Genera about 130; Acca, Accara, Acmena, Acmenosperma, Actinodium, Agonis, Allosyncarpia, Amomyrtella, Amomyrtus, Angasomyrtus, Angasomyrtus, Angophora, Aphanomyrtus, Archirhodomyrtus, Arillastrum, Astartea, Asteromyrtus, Austromyrtus, Backhousia, Baeckia, Balaustion, Barongia, Basisperma, Beaufortia, Blepharocalyx, Callistemon, Calothamnus, Calycolpus, Calycorectes, Calyptranthes, Calyptrogenia, Calytrix, Campomanesia, Carpolepis, Chamelaucium, Chamguava, Choricarpia, Cleistocalyx, Cloezia, Conothamnus, Corynanthera, Corynemyrtus, Cupheanthus, Darwinia, Decaspermum, Eremaea, Eucalyptopsis, Eucalyptus, Eugenia, Gomidesia, Feijoa (=Acca), Heteropyxis, Hexachlamys, Homalocalyx, Homalospermum, Homoranthus, Hottea, Hypocalymma, Jambosa, Kania, Kjellbergiodendron, Kunzea, Lamarchea, Legrandia, Lencymmoea, Leptospermum, Lindsayomyrtus, Lophomyrtus, Lophostemon, Luma, Lysicarpus, Malleostemon, Marlieria, Melaleuca, Meteoromyrtus, Metrosideros, Micromyrtus, Mitranthes, Mitrantia, Monimiastrum, Mosiera, Mozartia, Myrceugenia, Myrcia, Myrcianthes, Myrciaria, Myrrhinium, Myrtastrum, Myrtella, Myrteola, Myrtus, Neofabricia, Neomitranthes, Neomyrtus, Ochrosperma, Octamyrtus, Osbornia, Paramyrciaria, Pericalymma, Phymatocarpus, Pileanthus, Pilidiostigma, Piliocalyx, Pimenta, Pleurocalyptus, Plinia, Pseudanamomis, Pseudeugenia, Psidium, Purpureostemon, Pyrenocarpa, Regelia, Rhodamnia, Rhodomyrtus, Rinzia, Ristantia, Rylstonea, Scholtzia, Siphoneugenia, Sphaerantia, Stereocaryum, Syncarpia, Syzygium, Tepualia, Thryptomene, Tristania, Tristaniopsis, Ugni, Uromyrtus, Verticordia, Waterhousea, Welchiodendron, Whiteodendron, Xanthomyrtus, Xanthostemon.
Economic uses, etc. Many sources of essential oils for perfumery and medicine, and edible fruits from (e.g.) Feijoa (Brazilian guava, etc.), Eugenia spp. (jambos, rose-apple, pitanga etc.), Campomanesia (guabiroba).
Illustrations. • Technical details (Beaufortia, Myrtus). • Technical details (Eugenia). • Technical details (Calythrix, Eucalyptus, Leptospermum).
Quotations
Once a jolly swagman camped by a billabong,
Under
the shade of a Coolabah tree
(A.B. Paterson, ‘Waltzing Matilda’ -
Eucalyptus microtheca)
A lemon
Stuck with cloves
(‘Love’s Labour’s Lost’, v., 2 - Eugenia)
Cite this publication as: ‘L. Watson and M. J. Dallwitz (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 14th December 2000. http://biodiversity.uno.edu/delta/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Watson and Dallwitz (1991) should also be cited (see References).
