Neotropical Monimiaceae

Susanne Renner

Ludwig-Maximilian University of Munich, München, Germany. 

Description

Evergreen scambling shrubs, treelets or trees, with spherical oil cells in all parts of the plants. Leaves oppposite, decussate or in whorls of 3-4, simple, exstipulate, those of a pair often unequal in size, with simple or stellate hairs, glabrescent, the margin variously serrate, dentate, or entire. Inflorescences axillary or cauliflorous, cymose or fasciculate. Flowers radial, unisexual or rarely bisexual, plants dioecious, floral cup (receptacle) well-developed (the perigon perigynous), subglobose or cup-shaped, tepals 3 to numerous, petaloid, sepaloid, or connate and forming a calyptra; stamens few to very numerous, dispersed irregularly in the floral cup, filaments lacking appendages or more rarely with paired basal nectary glands on the filaments, anthers with 4 pollen sacs dehiscing by longitudinal, lateral, or circumscissile slits; carpels 1 to numerous, free or immersed in and fused with the receptacle tissue, the stigmas and/or styles free or joined by mucilage plugs, ovules solitary, pendulous and anatropous, bitegmic, crassinucellate. Fruiting receptacle repand and with few to many sessile or stipitate drupes, or the drupes enclosed in a fleshy receptacle and exposed at maturity by the splitting of the receptacle; the mesocarp fleshy, rarely half covered by an orange stylar aril, the endocarp stony.

Notes on delimitation

  • Morphologically and molecularly strongly supported as monophyletic (once Siparunaceae, Atherospermataceae, Amborellaceae, and Trimeniaceae were excluded).

Distribution in the Neotropics

Currently 28 genera and 195-200 species, mostly in the Malagasy floristic region, New Guinea (this has 75 species), and the Neotropics (four genera and ca. 24 species), with a few species in the rest of Malesia, Eastern Australia, and New Zealand. A single species, Xymalos monospora Baill., occurs from South Africa to Kenya, Uganda, and Cameroon.

  • Hennecartia Poisson: monospecific (H. omphalandra Poisson), Argentina.
  • Macropeplus Perkins: monospecific (M. ligustrinus (Tul.) Perkins) in gallery forest of southern Brazil, Paraguay, and Argentina.
  • Macrotorus Perkins: monospecific (M. utriculatus (Mart.) Perkins) in gallery forest of southern Brazil, Paraguay, and Argentina.
  • Mollinedia Ruiz & Pav.: ca. 20 species in understorey lowland moist forest, from Central America to the Amazon basin and in gallery forests in Brazil, Paraguay, and Argentina.
  • Peumus Molina: monospecific (P. boldus Molina) included here despite being outside the Flora region, in sclerophyllous Chilean forests between 30º and 41º latitude.

Distinguishing characters (always present)

  • Leaves opposite, decussate or in whorls of 3 to 4.
  • Flowers closed, somewhat fig-like, only the style tips or anther tips emerging from an apical ostiole.

Key differences from similar families

  • Rarely confused.

Number of genera

See above.

Useful tips for generic identification

  • An inordinate number of genera are monotypic (and hence devoid of informative generic characters).
  • Several others are poorly circumscribed.
  • Renner et al. 2010 paper, which has sequences for all but one genus and the majority of species.

Status

  • Monimiaceae are not cultivated, with the exception of Peumus, which is cultivated in a few botanical gardens in Europe.

General notes

  • The fossil record of Monimiaceae is relatively extensive. Fossils from the Upper Senonian of the eastern Cape Province (Hedycaryoxylon hortonioides Mädel) and the Upper Cretaceous (Campanian) of James Ross Island in Antarctica (Hedycaryoxylon tambourissoides Poole & Gottwald) undoubtedly represent Monimiaceae. Somewhat younger fossil woods, referred to Xymaloxylon zeltenense (Louvet) Louvet (syn. Monimiaxylon zeltenense Louvet), have been described from the Early Oligocene of Oman.
  • There are also leaves from Paleocene/Eocene boundary strata on King George Island, Antarctic Peninsula (Monimiophyllum antarcticum Zastawniak). Even fossil woods from the Late Eocene of Germany, namely Hedycaryoxylom subaffine (Vater) Süss and Hortonioxylon henericiungeri Gottwald, have been compared to Hortonia Wight ex Arn., Hedycarya Forst., and Tambourissa Sonn. [This is from S. S.Renner, unpublished manuscript, which contains all the refs.]

Important literature

Philipson, W.R. 1986. Monimiaceae. In: Steenis, C.G.G.J. van, ed. Flora Malesiana Spermatophyta: flowering plants. vol.10, part 2. Revisions. Dordrecht etc., Martinus Nijhoff Publishers. 255-326.

Renner, S.S. 2004. Monimiaceae. Pp. 252-253. In: Smith, N., Mori, S.A., Henderson, A., Stevenson, D.W. & Heald, S.V. (eds.). Flowering Plants of the Neotropics. New York Botanical Garden, Princeton University Press, Princeton.

Renner, S.S., and Hausner, G. 1997. Siparunaceae, Monimiaceae. In: Harling, G. & Andersson, L. (eds.). Flora of Ecuador no. 59, Pp. 1-124. Department of Systematic Botany, University of Gothenburg, Gothenburg.

Renner, S. S., J. S. Strijk, D. Strasberg, and C. Thébaud. 2010. Biogeography of the Monimiaceae (Laurales): A role for East Gondwana and long distance dispersal, but not West Gondwana. Journal of Biogeography 37(7): 1227-1238.

How to cite

Rener, S. (2009). Neotropical Monimiaceae. 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/Monimiaceae.htm.