Neotropical Metteniusaceae

Jon L.R. Every

Royal Botanic Gardens, Kew, UK. 

Description

Evergreen trees (4-20m tall); indumentum of 2-branched hairs. Leaves simple, alternate, petiolate, leathery, margins entire; venation pinnate, tertiary veins parallel and +/- perpendicular to the midrib. Inflorescence an axillary cyme of up to 17 flowers. Flowers on short pedicels, bracteate, actinomorphic, bisexual; calyx 5 lobed, imbricate, slightly fused at the base, persistent in fruit; corolla fused for 1/3 of its length into a narrow tube, 5 lobed, lobes reflexed, inner surface tomentose; stamens 5, alternipetalous, adnate to corolla, strongly exserted, monifliform, hairy sagittate anthers; ovary superior, carpels 4 highly reduced (appearing monomerous), unilocular, ovule 1, pendent from the apex, style 1, 2cm long. Fruit a drupe, asymmetrically ridged, 5-ribbed, mesocarp leathery, endocarp woody, indehiscent. Seed 1, endosperm abundant, white.

Notes on delimitation

  • The genus has been hard to place and has mainly found itself as a member of the Icacinaceae.
  • The Metteniusaceae has, however, been sporadically accepted as a family in its own right ever since Karston (1859) described it in the Flora of Colombia.
  • Recent molecular work has strengthened the case for the monotypic family as Gonzalez et al (2007) placed Metteniusa H.Karst. as an isolated genus near the base of the lamiid clade.

Distribution in the Neotropics

  • Canopy trees found from Costa Rica in montane forests down along the Andes of Colombia to Venezuela and into Ecuador and Peru at up to 2,000m.

Distinguishing characters (always present)

  • Flowers c. 4 cm.
  • Moniliform anthers (resembling a string of beads), 1 cm long.
  • Uniovulate ovaries.
  • Stamens connected to the petals.
  • 2 bracts immediately below the calyx.
  • Stamens exserted.
  • Filaments 1.5 cm long, free and curled backwards.
  • Style 2 cm in length.

Other important characters

Key differences from similar families

Metteniusa can be told apart from the following families (some of which have contained the genus) by the highlighted features, which the Metteniusaceae do not have:

Number of genera

  • Monogeneric: Metteniusa H.Karst.

Status

  • Exclusively Neotropical.

General notes

  • M. edulis H. Karst. has fruits which are reportedly edible.

Important literature

González, F., J. Betancur, O. Maurin, J. V. Freudenstein & Mark W. Chase. 2007. Metteniusaceae, an early-diverging family in the lamiid clade. Taxon 56(3): 795-800.

Howard, R. A. 1940. Studies of Icacinaceae. I. Genera to be excluded. Journal of the Arnold Arboretum 21: 485-6.

Karsten, G. K. W. H. 1859. Metteniusaceae. Pp79-80, t. 39 in: Florae Colombiae 1. Ferdinandi Duemmleri successors, Berlin.

Kårehed, J. 2001. Multiple origin of the tropical forest tree family Icacinaceae. American J. Bot. 88: 2259-2274.

Lozano-C., G. & de Lozano, N. B. 1988. Metteniusaceae. Flora de Colombia 11. Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Bogata.

Maas, P. J. M. & Westra, L. Y. Th. 2005. Neotropical Plant Families. 3rd ed. P. 307. A.R.G. Gantner Verlag K.G., Ruggell.

Stevens, P. F. (2008). Angiosperm Phylogeny Website. Version 9 onwards. http://www.mobot.org/MOBOT/research/APweb/.

Utteridge, T.M.A. and Brummitt, R.K. 2007. Metteniusaceae. In: Heywood, V.H., Brummitt, R.K., Culham, A. and Seberg, O. (eds.). Flowering plant families of the world, p. 215. Kew: Royal Botanic Gardens, Kew.

How to cite

Every, J.L.R. (2009). Neotropical Metteniusaceae. 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/Metteniusaceae.htm.