Neotropical Memecylaceae

Elizabeth M. Woodgyer

Royal Botanic Gardens, Kew, U.K. 

Description

Trees (small to large) or shrubs, mostly evergreen, usually glabrous; branchlets terete, 4-angled or 4-winged. Nodes swollen, stipules absent or represented by an interpetiolar line, minute fringe, short lacerate membrane or series of small scales or awns. Leaves opposite, decussate, simple, entire, pinnate-nerved (sometimes only midrib apparent or rarely subtrinerved), sclereids typically attached to ends of veinlets, blades sometimes irregularly translucent-speckled when held to light (due to sclereids), stomata usually paracytic (in specialized crypts), sessile or short-petiolate. Inflorescences at nodes of young wood, ramiflorous or cauliflorous, cymose, umbelloid, fasciculate or sometimes flowers solitary at nodes of older wood. Flowers actinomorphic, bisexual, 4- or 5-merous; bracts small and often deciduous; hypanthium fused to ovary, calyx tube well-developed to absent, calyx lobes free and minute; petals free, equal to number of calyx lobes, convolute in bud, often asymmetrical, apex acute to acuminate, base often clawed, yellow, orange, cream, white, pink, violet or purple, rarely red, sclereids numerous (Votomita) or absent (Mouriri); stamens isomorphic to somewhat dimorphic, twice as many as petals, anthers basifixed, apically dehiscent by 2 short slits, filament usually doubled back towards the style base in the bud, straightening at anthesis (Mouriri), or filaments straight or nearly so in bud (Votomita & 4 spp. of Mouriri), connective with a dorsal terpenoid-producing gland; ovary fully inferior, carpels equal to number of locules, locules 1-5, placentation free central, axile, basal, axile-basal or parietal, ovules up to 16 per locule but usually fewer, style elongate, stigma punctate. Fruit a berry, subglobose, usually yellow to red at maturity, occasionally pale green, purple-black or black. Seeds 1-5(-12), large, polished (Mouriri) or unpolished (Votomita), cotyledons thick and fleshy.

Notes on delimitation

  • Memecylaceae has often been treated as a separate family (APG 1998) or included within Melastomataceae as a subfamily (Cronquist 1988). Previous studies based on chloroplast DNA sequences suggested that Memecylaceae was perhaps sister to Melastomataceae (Clausing & Renner 2001), but recent analyses of molecular and morphological data provide strong support for the monophyly of subfamily Olisbeoideae (comprising 6 genera including Mouriri and Votomita) and its recognition as one of four Melastomataceae subfamilies (Stone 2006).

Distribution in the Neotropics

  • Mostly in lowland moist tropical to subtropical forests and thickets or savannas, from mid-Mexico through Central America to Bolivia, the Guianas, Brazil and in the West Indies. The greatest number of species is found in the Amazon basin.
  •  Mouriri Aubl.: Mexico, C. America, West Indies, Colombia, Venezuela, Guyana, Suriname, French Guiana, Ecuador, Peru, Brazil & Bolivia.
  • Votomita Aubl.: Panama, Cuba, Colombia, Guyana, Suriname, French Guiana, Peru & Brazil.

Distinguishing characters (always present)

Other important characters

  • Glabrous.
  • Nodes swollen.
  • Leaves pinnately veined (sometimes only midrib apparent or rarely subtrinerved).
  • Sclereids (stone cells) present in leaves and sometimes petals.
  • Stomata paracytic (borne inside invaginated pits) on lower leaf surface.
  • Observe number of flower parts.
  • Presence/absence of a free hypanthium (calyx tube).
  • Presence/absence of stone cells in petals.
  • Observe stamens: filament doubled back towards the style base in bud, straightening out at anthesis and filament more or less straight in bud.
  • Anther connective with a dorsal terpenoid-producing gland.
  • Type of placentation.
  • Observe the seed (polished or unpolished).

Key differences from similar families

The following families differ from Memecylaceae in the characters listed:

 

Number of genera

  • 6 genera and c. 350 spp. worldwide.
  • 2 genera in the Neotropics: Mouriri Aubl. (c. 85 spp.) & Votomita Aubl. (10 spp.).

Useful tips for generic identification

Key to genera of Neotropical Memecylaceae

1. Flowers (4-)5-merous; anthers straight or curved, usually on elongate filaments infolded in bud; free hypanthium (calyx tube) usually present; seed polished at least on enlarged outer face of the ovule, often all over except for hilum; petals lacking stone cells; ovules as below or partly or wholly anatropous ... Mouriri

1. Flowers 4-merous; anthers straight on short, non-folded filaments, sporangia adaxial, gland terminal; free hypanthium (calyx tube) lacking; seed unpolished; petals containing numerous box-shaped stone cells unattached to veins; ovules bent at a sharp angle from a broad chalazal attachment... Votomita

Notable genera and distinguishing features


 

Status

  • The wood of some species of Mouriri is used for general construction.
  • Many species have fleshy, edible wild fruit and appear in local markets eg. Mouriri pusa from Brazil (local name Púsa or Puca).

General notes

  • Often tall trees that can reach 35 m in height and 60 cm in diameter.
  • Canopy trees are unbuttressed, but have basally swollen trunks and small, round crowns.
  • Smaller-fruited species are bird-dispersed; some larger-fruited species are monkey-dispersed.
  • Germination cryptocotylar (cotyledons remain inside the seed).
  • Placentation varies remarkably in Memecylaceae and is of great value taxonomically.
  • The ecological role of the terpenoid exudate produced by the dorsal anther glands is unclear. The glands may play a role in odor production or visual orientation to the pollen source.

Important literature

APG (Angiosperm Phylogeny Group). 1998. An ordinal classification for the families of flowering plants. Ann. Missouri Bot. Gard. 85(4): 531-553.

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

Cronquist, A. 1988. An integrated system of the classification of flowering plants. Colombia University Press, New York.

Morley, T. 1976. Memecyleae (Melastomataceae). Flora Neotropica Monograph No. 15: 1-295.

Morley, T. 1993. Memecyloideae. In: A.R.A. Görts-Van Rijn (ed.), Flora of the Guianas, Ser. A, 99: 302-336. Koeltz, Koenigstein.

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

Stone, R.D. 2006. Phylogeny of major lineages in Melastomataceae subfamily Olisbeoideae: Utility of nuclear glyceraldehyde 3-phosphate dehydrogenase (GapC) gene sequences. Syst. Bot. 31(1): 107-121.

How to cite

Woodgyer, E.M. (2009). Neotropical Memecylaceae. 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/Memecylaceae.htm.