Melastomataceae Juss.

Melastomataceae, G. E. Wickens. Flora of Tropical East Africa. 1975

Morphology General Habit

Trees, shrubs or more commonly herbs, rarely climbers, sometimes epiphytes

Morphology Leaves

Leaves opposite and decussate, rarely verticillate, sometimes anisophyllous, simple to entire, serrate, exstipulate, usually with a distinctive nervation of 2–8 strong basal nerves ± parallel to the midrib, rarely pinnately nerved

Morphology Reproductive morphology Inflorescences

Inflorescences various, sometimes bracteate

Morphology Reproductive morphology Flowers

Flowers hermaphrodite, regular (androecium sometimes slightly zygomorphic), mostly 4–5(–6)-merous

Morphology Reproductive morphology Flowers Calyx

Calyx tubular or campanulate, free or partially adnate to the ovary or sometimes connected to it by septa-like strands (no distinction is made here between the hypanthium and calyx proper); lobes valvate or connate and forming a calyptra-like head in bud, deciduous or persistent; various appendages may alternate with or arise from the calyx-lobes

Morphology Reproductive morphology Flowers Corolla

Petals 4–5, free or rarely united at the base, imbricate or convolute, often magenta coloured

Morphology Reproductive morphology Flowers Androecium

Stamens perigynous or epigynous, as many as the petals or more usually twice as many as the petals and in 2 whorls, the whorls equal to very unequal; anthers usually 2-thecous, introrse, basifixed, each anther dehiscing by a single pore or more rarely by a slit (Memecylon); anther-connectives often elongated and often either tubercled or spurred at the junction with the filament; filaments often geniculate, inflexed in bud, sometimes twisted

Morphology Reproductive morphology Flowers Gynoecium

Ovary 1-locular with basal placentation >i>(Memecylon) to several-locular with axile placentation; ovules usually numerous; style and stigma 1

Morphology Reproductive morphology Fruits

Fruit a loculicidal capsule or a berry

Morphology Reproductive morphology Seeds

Seeds small or minute, without endosperm and with a very small embryo; one cotyledon larger than the other

Melastomataceae, Hutchinson and Dalziel. Flora of West Tropical Africa 1:1. 1954

Morphology General Habit

Herbs, shrubs or trees; branches opposite

Morphology Leaves

Leaves simple, opposite or verticillate, mostly with 3 to 9 longitudinally parallel nerves; stipules 0

Morphology Reproductive morphology Flowers

Flowers hermaphrodite, mostly very showy, actinomorphic

Morphology Reproductive morphology Flowers Calyx

Calyx tubular, free or adnate to the ovary, or sometimes connected to it by septa-like strands; lobes imbricate or rarely valvate

Morphology Reproductive morphology Flowers Corolla

Petals imbricate, free, rarely united at the base

Morphology Reproductive morphology Flowers Corona

Corona sometimes present

Morphology Reproductive morphology Flowers Androecium

Stamens the same to double the number of the petals; filaments free, often geniculate, inflexed; anthers 2-celled, opening by a pore at the apex or rarely by a slit (Memecylon), connective often appendaged at the base

Morphology Reproductive morphology Flowers Gynoecium

Ovary mostly inferior, 1- to many-celled; style simple; ovules numerous, axile, or rarely basal or parietal

Morphology Reproductive morphology Fruits

Fruit a capsule or berry

Morphology Reproductive morphology Seeds

Seeds minute, without endosperm

Melastomataceae, R. and A. Fernandes. Flora Zambesiaca 4. 1978

Morphology General Habit

Perennial or annual erect or prostrate terrestrial or epiphytic herbs, lianes, shrubs or trees, with a variable indumentum or glabrous

Morphology Leaves

Leaves opposite or sometimes verticillate, longitudinally (1)3–5–7(1 l)-nerved, rarely penninerved, simple, without stipules

Morphology Reproductive morphology Flowers

Flowers actinomorphic or zygomorphic as regards the stamens, bisexual, (3)4–5(6)-merous Flowers in cymes, arranged in heads, fascicles or in ± ample panicles, rarely flowers solitary

Morphology Reproductive morphology Flowers Receptacle

Receptacle free or adherent to the ovary by longitudinal ridges or ± adnate to it

Morphology Reproductive morphology Flowers Calyx

Sepals imbricate or rarely subvalvate, caducous or persistent, rarely 0; intersepalar segments sometimes present

Morphology Reproductive morphology Flowers Corolla

Petals as many as the sepals, inserted on the margin of the receptacle, very rarely connate at the base, imbricate or contorted

Morphology Reproductive morphology Flowers Androecium

Stamens epigynous, rarely perigynous, twice as many or rarely as many as the petals; filaments free, inflected in the bud; anthers basifixed, 2-locular, dehiscing by 1 apical pore (rarely by 2 and very rarely by 4) or by 2 longitudinal slits; connective produced or not at the base and provided anteriorly and/or posteriorly with appendages of several types

Morphology Reproductive morphology Flowers Gynoecium

Ovary 2-¥-locular or 1-locular by suppression of the dissepiments (Memecylon), glabrous, setose or with scales at the apex; style 1, terminal, straight or curved with a dot-like or subcapitate stigma; ovules anatropous

Morphology Reproductive morphology Fruits

Fruit a many-seeded capsule, sometimes baccate, included in the receptacle, rarely semiexserted, opening by loculicidal valves, rarely dehiscing irregularly, or a berry, 1-few-seeded

Morphology Reproductive morphology Seeds

Seeds minute, cochleate, cuneiform, pyramidal or cylindrical in the many-seeded genera and globose or hemispherical in the few-seeded ones; embryo subcylindric or sub-globose, without endosperm

Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://creativecommons.org/licenses/by/3.0

Morphology General Habit

Trees (rarely tall), treelets, shrubs, herbs, lianas and epiphytes, stems often quadrangular

Morphology General Indumentum

Epidermis glabrous or with an elaborate indumentum varying from simple, unicellular hairs to complex multicellular, non- glandular or eglandular trichomes

Morphology Leaves

Leaves opposite, exstipulate, decussate simple, entire or dentate and usually petiolate, with 2-8 lateral primary veins running sub -parallel to leaf margin diverging from or above base and converging towards  apex (sometimes uni-nerved, rarely pinnately veined); anisophylly and ant domatia (typically in the leaf bases) quite common

Morphology Reproductive morphology Inflorescences

Inflorescences terminal and/or axillary, paniculate cymes, racemes, umbels or occasionally in glomerules, fascicles or flowers solitary

Morphology Reproductive morphology Flowers

Flowers actinomorphic or often with zygomorphic stamens, often bracteolate, hermaphrodite; hypanthium campanulate or urn-shaped; calyx lobes (3)4-5(-8), usually regularly lobed and imbricate to valvate, sometimes indistinct or absent, sometimes with external teeth or fused to form a calyptra; petals equal to number of calyx lobes, imbricate in bud, free, right- contorted, usually spreading, white, pink, purple, magenta or red, seldom orange or yellow; stamens usually twice as many as petals, isomorphic or dimorphic with inner set smaller than outer, anthers basifixed, apically dehiscent by 1-2(-4) pores, connective often prolonged and variously appendaged ventrally and/or dorsally; ovary superior to inferior (hypanthium free or adhering to  ovary completely or partially), locules 3-6, style single, elongate, stigma punctate to capitate

Morphology Reproductive morphology Fruits

Fruits fleshy berries or a loculicidal capsules

Morphology Reproductive morphology Seeds

Seeds numerous, straight, cuneate or curved (cochleate).

Diagnostic

Stems often quadrangular. Leaves opposite (rarely pseudo-alternate) and decussate. Epidermis often with an elaborate indumentum (glandular, stellate or simple hairs and emergences). Acrodromal venation - leaf blades with 2-8 primary lateralveins running sub-parallel to the leaf margin, diverging from or above the base and converging towards the apex. Filaments commonly twisted at anthesis bringing anthers to one side of the flower. Stamen connectives often prolonged and variously appendaged ventrally and/or dorsally. Seeds numerous. Distinguishing characters (always present): Leaves simple. Stipules absent. Hypanthium present (free or adhering to the ovary completely or partially). Petals free, right-contorted. Tribe Blakeeae: flowers 6-merous, axillary, subtended by 2 pairs of persistent floral bracts; leaves thick, conspicuously cross-venulate, often with numerous strictly parallel lateralveins; fruit a berry. Blakea: (100 spp.); trees, shrubs or woody vines (often epiphytic); anthers compressed laterally with 2 well-separated apical pores.   Tribe Melastomeae: often elaborate and conspicuous trichomes on leaves and hypanthia; stamens with basal-ventrally prolonged connectives; ovary crowned by persistent trichomes; fruit a capsule; seeds cochleate. Brachyotum: (c. 58 spp.); shrubs or small trees; flowers pendulous; petals free but connivent and imbricate in a campanulate tube, often dark purple; stamens isomorphic. Tibouchina: (c. 240 spp.); herbs, shrubs or small trees; flowers often showy; petals often magenta or deep purple; stamens often dimorphic; anther connectives ventrally bi-lobed.   Tribe Merianieae: leaves leathery; flowers large; stamens dorsally thickened and variously spurred; fruit a capsule. Meriania: (c. 74 spp.); trees or shrubs; inflorescences usually terminal panicles; connective with a dorso-basal spur and sometimes with an ascending dorsal appendage also; seeds narrowly oblong -pyramidal.   Tribe Miconieae: flowers 4-5 merous; short to elongate and persistent external calyx teeth; ovary inferior; fruit a berry. Clidemia: (c. 175 spp.); erect (rarely scandent or radicant) shrubs; often densely setose; inflorescences lateral or pseudolateral cymes in upper leaf axils or at branchlet nodes below the leaves. Leandra: (c. 200 spp.); shrubs (rarely woody vines); flowers in terminal (sometimes pseudoterminal) panicles; petalapexacute to acuminate. Miconia: the largest genus (1,000 spp.); shrubs or trees; flowers in terminal panicles; petalapexrounded.   Tribe Microlicieae: shrubby; often microphyllous; basally prolonged anther connectives; anthers rostrate; ovaryglabrous; seeds oblong or reniform with a foveolate testa. Microlicia: (c. 170 spp.); branched shrubs or subshrubs, often ericoid; ovarysuperior; fruit capsular, dehiscing longitudinally from apex to base. Presence/absence of stamen connective appendages. Position of appendages (ventral and/or dorsal). Number of calyx lobes/petals. Number of locules. Shape and surface of seed (straight with a smooth or tubulate surface, straight with a foveolate surface or cochleate with a tubulate surface). Ovary position (superior or inferior). Type of fruit (capsule or berry). Key differences from similar families: The families listed below differ from Melastomataceae in the following features:   From LoganiaceaeStrychnos (similar leaf venation): Tendrils often present. Corolla tubular. Stamens inserted on corolla tube.   From Myrtaceae (similar hypanthium, petals free): Leaves with pellucidgland dots. Leaves aromatic. Stamens numerous (>100).   From Memecylaceae (similar hypanthium, petals free): Leaves pinnate -veined. Leaf sclereids present. Anther connective with a dorsal terpenoid-producing gland. Fruit a berry with 1-12 large seeds.   From Rubiaceae (similar opposite leaves, hypanthium): Interpetiolar stipules present. Corolla gamopetalous. Anthers dehiscent -longitudinally.   From Urticaceae (similar leaf venation): Cystoliths on leaves and stems. Stipules usually present. Flowers small, usually greenish and unisexual. Fruit an achene.

Distribution

Tibouchina are grown as ornamentals, often street trees (Tibouchina granulosa Cogn., T. mutabilis Cogn.). Miconiacalvescens DC. and Clidemia hirta D.Don are aggressive weeds which have spread to the Pacific islands. Widely distributed in the Neotropics, extending as far south as northern Argentina.

Note

Bellucia have wild edible fruit. Some microphyllous species (particularly in Microlicia) have leaves with a single mid-vein only, but can easily be assigned to this family by their distinctive stamens (scythe-shaped, poricidal anthers and prolonged, often appendaged connectives). A few isolated taxa, eg. Heterocentron, Loreya nigricans Triana and Macairea rufescens DC., have pinnately veined leaves. The family name comes from the Greek words mela meaning black and stoma meaning mouth. Eating the edible, purple-blue berries will stain the mouth black. Nectar production is rare in Melastomataceae and most species are visited by pollen-gathering bees that use thoracic vibrations (buzz pollination) to expel the pollen through the anther pores. The characteristic anther appendages probably function as a hold for the bee's legs. Notes on delimitation: Melastomataceae has always been considered a core family of the Myrtales and this is supported by molecular phylogenetic analyses (APG II, 2003). Melastomataceae was traditionally divided into 13 tribes (according to Triana's classification published in 1866 and slightly modified in 1871). Several have recently been recircumscribed as a result of morphological and molecular analyses (Clausing & Renner 2001, Renner 2004). The nine monophyletic tribes currently accepted are as follows:   Astronieae (SE Asia). Bertolonieae (Neotropical). Blakeeae (Neotropical). Dissochaeteae (Paleotropical). Kibessieae (SE Asia). Melastomeae (Pantropical). Merianieae (Neotropical). Miconieae (Neotropical). Microlicieae (Neotropical) - 90% of spp. endemic to the highlands of Eastern and Central Brazil. Memecylaceae is sometimes ranked as a subfamily of Melastomataceae, but it is treated as a separate family here. Number of genera: 150-166 genera and c. 4,570 species worldwide 107 genera and c. 3,000 species in the Neotropics Acanthella Hook.f. Aciotis D.Don Acisanthera P.Browne Adelobotrys DC. Allomaieta Gleason Alloneuron Pilg. Anaectocalyx Triana ex Benth. & Hook.f. Appendicularia DC. Arthrostemma Pav. ex D.Don Axinaea Ruiz & Pav. Behuria Cham. Bellucia Neck. ex Raf. Benevidesia Saldanha & Cogn. Bertolonia Raddi Bisglaziovia Cogn. Blakea P.Browne Boyania Wurdack Brachyotum Triana Bucquetia DC. Calycogonium DC. Cambessedesia DC. Castratella Naudin Catocoryne Hook.f. Centradenia G.Don Centradeniastrum Cogn. Centronia D.Don Chaetolepis Miq. Chaetostoma DC. Chalybea Naudin Charianthus D.Don Clidemia D.Don Comolia DC. Comoliopsis Wurdack Conostegia D.Don Cyphostyla Gleason Desmoscelis Naudin Diplarpea Triana Dolichoura Brade Eriocnema Naudin Ernestia DC. Fritzschia Cham. Graffenrieda DC. Henriettea DC. Henriettella Naudin Heterocentron Hook. & Arn. Huberia DC. Huilaea Wurdack Killipia Gleason Kirkbridea Wurdack Lavoisiera DC. Leandra Raddi Lithobium Bong. Llewelynia Pittier Loreya DC. Loricalepis Brade Macairea DC. Macrocentrum Hook.f. Maguireanthus Wurdack Maieta Aubl. Mallophyton Wurdack Marcetia DC. Mecranium Hook.f. Meriania Sw. Merianthera Kuhlm. Miconia Ruiz & Pav. Microlicia D.Don Microlepis Miq. Mommsenia Urb. & Ekman Monochaetum (DC.) Naudin Monolena Triana Myriaspora DC. Neblinanthera Wurdack Necramium Britton Nepsera Naudin Ochthephilus Wurdack Opisthocentra Hook.f. Ossaea DC. Pachyanthus A.Rich. Pachyloma DC. Pentossaea Judd Phainantha Gleason Physeterostemon R.Goldenb. & Amorim Pilocosta Almeda & Whiffin Pleiochiton Naudin ex A.Gray Poteranthera Bong. Pseudoernestia Krasser Pterogastra Naudin Pterolepis (DC.) Miq. Rhynchanthera DC. Salpinga Mart. ex DC. Sandemania Gleason Schwackaea Cogn. Siphanthera Pohl Stanmarkia Almeda Stenodon Naudin Svitramia Cham. Tateanthus Gleason Tessmannianthus Markgr. Tetrazygia Rich. ex DC. Tibouchina Aubl. Tibouchinopsis Markgr. Tococa Aubl. Topobea Aubl. Trembleya DC. Triolena Naudin Tryssophyton Wurdack Wurdastom B.Walln.

Timothy M. A. Utteridge and Laura V. S. Jennings (2022). Trees of New Guinea. Kew Publishing. Royal Botanic Gardens, Kew

Distribution

A family of about 150 genera and 4500 species with a pantropical distribution and the centre of diversity in the Neotropics.

Recognition

Melastomataceae are one of the most easily recognised tropical families, with opposite leaves with conspicuously curving lateral veins and without stipules, flowers with <10 stamens and sickle-shaped anthers. Members of the Melastomataceae are notoriously brittle when dried and floral parts in particular are easily lost, but at the same time it must be noted that stamen morphology is vital for the identification of some New Guinea genera; for example, to distinguish Astronia Noronha from Astronidium A.Gray. The most useful material is from specimens with partly open buds – the parts are sufficiently developed but likely to persist in dried material. The calyx lobes are fused at the base forming a tube which may have apical lobes or teeth which are of taxonomic importance, as well as the degree of fusion of the ovary to the hypanthium.

Morphology General Habit

Trees, shrubs, climbers, epiphytes and herbs

Morphology General Indumentum

Indumentum very diverse

Morphology Leaves Stipules

Stipules absent

Morphology Leaves

Leaves opposite, rarely whorled, leaf pairs occasionally unequal, simple, margins entire or with teeth, frequently with 2 or more secondary veins equal in prominence to the midrib, originating from the base and ascending towards the apex (acrodromal). Inflorescences terminal or axillary, cymes or panicles, occasionally solitary flowers

Morphology Reproductive morphology Flowers

Flowers bisexual, rarely staminate and plants andromonoecious (Astronia), 4–5-merous; calyx partially fused with small lobes or teeth at the top of the tube, occasionally calyptrate; petals free, much larger than the calyx; stamens 4–5, 8 or 10(–96), may be dimorphic or equal, inflexed in bud, filaments free, may be twisted so stamens are all on one side of the flower, staminodes may be present, anthers sickle-shaped, dehiscing via apical pores or longitudinal slits; ovary inferior, completely adnate to hypanthium or partly connected to it by septa between which are pockets which house the inwardly bent anthers in bud

Morphology Reproductive morphology Fruits

Fruit a capsule or berry with many seeds.