Neotropical Melastomataceae

Elizabeth M. Woodgyer

Royal Botanic Gardens, Kew, UK. 

Description

Trees (rarely tall), treelets, shrubs, herbs, lianas and epiphytes, stems often quadrangular. Epidermis glabrous or with an elaborate indumentum varying from simple, unicellular hairs to complex multicellular, non-glandular or eglandular trichomes. 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. Inflorescences terminal and/or axillary, paniculate cymes, racemes, umbels or occasionally in glomerules, fascicles or flowers solitary. 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. Fruits fleshy berries or a loculicidal capsules. Seeds numerous, straight, cuneate or curved (cochleate).

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.

Distribution in the Neotropics

  • Widely distributed in the Neotropics, extending as far south as northern Argentina.

Distinguishing characters (always present)

Other important characters

  • 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 lateral veins 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.

Key differences from similar families

The families listed below differ from Melastomataceae in the following features:

 

From Loganiaceae Strychnos (similar leaf venation):

  • Tendrils often present.
  • Corolla tubular.
  • Stamens inserted on corolla tube.

 

From Myrtaceae (similar hypanthium, petals free):

 

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):

 

From Urticaceae (similar leaf venation):

  • Cystoliths on leaves and stems.
  • Stipules usually present.
  • Flowers small, usually greenish and unisexual.
  • Fruit an achene.

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.

Useful tips for generic identification

  • 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).

Notable genera and distinguishing features

Tribe Blakeeae: flowers 6-merous, axillary, subtended by 2 pairs of persistent floral bracts; leaves thick, conspicuously cross-venulate, often with numerous strictly parallel lateral veins; 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; petal apex acute to acuminate.
  • Miconia: the largest genus (1,000 spp.); shrubs or trees; flowers in terminal panicles; petal apex rounded.

 

Tribe Microlicieae: shrubby; often microphyllous; basally prolonged anther connectives; anthers rostrate; ovary glabrous; seeds oblong or reniform with a foveolate testa.

  • Microlicia: (c. 170 spp.); branched shrubs or subshrubs, often ericoid; ovary superior; fruit capsular, dehiscing longitudinally from apex to base.

Status

  • Tibouchina are grown as ornamentals, often street trees (Tibouchina granulosa Cogn., T. mutabilis Cogn.).
  • Miconia calvescens DC. and Clidemia hirta D.Don are aggressive weeds which have spread to the Pacific islands.

General notes

  • 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.

Important literature

APG II. 2003. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II. Bot. J. Linn. Soc. 141(4): 399-436.

Berry, P.E., Gröger, A., Holst, B.K., Morley, T., Michelangeli, F.A., Luckana, N.G., Almeda, F., Renner, S.S., Freire-Fierro, A., Robinson, O.R. & Yatskievych, K. 2001. Melastomataceae. In: Steyermark, J.A., Berry, P.E., Yatskievych, K., & Holst, B.K. (eds), Flora of the Venezuelan Guayana 6: 263-528.

Clausing, G. & Renner, S.S. 2001. Molecular phylogenetics of Melastomataceae and Memecylaceae: implications for character evolution. American J. Bot. 88(3): 486-498.

Heywood, V.H., Brummitt, R.K., Culham, A. & Seberg, O. 2007. Flowering plant families of the world. 424 pp. Royal Botanic Gardens, Kew.

Renner, S.S. 1993. Phylogeny and classification of the Melastomataceae and Memecylaceae. Nord. J. Bot. 13: 519-540.

Renner, S.S. 2004. Bayesian analysis of combined chloroplast loci, using multiple calibrations, supports the recent arrival of Melastomataceae in Africa and Madagascar. Amer. J. Bot. 91(9): 1427-1435.

Wurdack, J.J. 1973. Melastomataceae. In: Lasser, T. (ed.), Flora de Venezuela 8: 1-819.

Wurdack, J.J. 1980. Melastomataceae. In: Harling, G. & Sparre, B. (eds), Flora of Ecuador 13: 1-406. Göteborg, Sweden.

Wurdack, J.J. & Renner, S. 1993. Melastomatoideae. In: A.R.A. Görts-Van Rijn (ed.), Flora of the Guianas, Ser. A, 99. Melastomataceae. Koeltz, Koenigstein.

How to cite

Woodgyer, E.M. (2009). Neotropical Melastomataceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Melastomataceae.htm.