1. Mitrastemonaceae Makino

    1. This family is accepted.

[NTK]

Every, J.L.R. (2009). Neotropical Mitrastemonaceae.

Morphology
Description

Holoparasitic, achlorophyllus, rootless with a filamentous endophyte in roots of host, 5-8 cm high. Leaves opposite decussate , whorled around the base of the solitary flower , reduced or absent, scale-like, coriaceous , apex obtuse . Flowers terminal , solitary, erect , nectaries in axils of upper bracts, actinomorphic , hermaphroditic, protandrous, gamophyllus, cupiliform, calyx of 4(-10) sepals, imbricate , truncate or a more or less 4- lobed collar around pistil , persistent ; petals absent; stamens fused to form a caducous tube ( androphore ), crowned by a fertile zone of pollen -bearing locules that has an opening at top; anthers numerous and in several series, above each other, opening by slits or pores; ovary superior , syncarpous, sessile , ovules numerous, carpels (4-)9-15(-20), 1-locular; style 1 terminal , short, very thick, stigma conic. Fruit a somewhat woody capsule opening by a transverse slit or indehiscent berries; seeds numerous, small, with a hard testa, exotesta juicy or papery surrounded by a whitish, slimy pulp.

General Description
Notes on delimitation
  • Mitrastemon Makino was thought to belong to the Rafflesiaceae alongside other Neotropical genera such as Cytinus L. (treated here in the Cytinaceae), Psilostylus Guill. plus the endemic Adodanthes Poit. and Bdallophyton Solms. Following the interpretation of the mitochondrial DNA sequences of the putative Rafflesiaceae it became apparent that Mitrastemon is in fact only distantly related to the Rafflesiaceae sensu lato and is actually placed as sister to the cranberry (Vaccinium L.) (Barkman 2003).
  • Originally described as Mitrastemma (the name was changed by Makino when he raised the genus to family rank), a name by which it is sometimes still referred.
Number of genera
  • Monogeneric with one species in the Neotropics.
General notes
  • From the Latin mitra and stema referring to the manner in which the stamens are connate into a turban-shaped tube.
  • Also recorded to have found suitable hosts outside the Fagales with members of Aquifoliacae, Compositae, Elaeocarpaceae, Juglandaceae and Myrtaceae providing the nutrient source for Mitrastemon (Nickrent 2004).
Distribution
Distribution in the Neotropics

Mitrastemon has two species one of which is represented in the Neotropics:

  • Mitrastemonmatudae Yamam. occurs from Mexico to Guatemala and into Northwestern Colombia.
Diagnostic
Distinguishing characters (always present)
  • Lack of green parts i.e. achlorophyllous.
  • Bisexual flowers.
  • Collar shaped, +/- 4-merousperianth tube.
  • Connate stamens (that split as the pistil develops from below).
  • Superior, unilocular ovary.
Other important characters
  • Often forming dense colonies.
  • Generally parasitic on members of the Fagaceae (e.g. Quercus L.).
  • Flowers are medium-sized (2-2.5 cm in diametre) and white.
  • Leaves are reduced to dark brown scales.
Key differences from similar families
  • Rafflesiaceae do NOT have bisexual flowers, nor a superiorovary.
  • Cytiniaceae do NOT have bisexual, solitary flowers.
Literature
Important literature

Barkman, T. J., Lim, S-H., Salleh, K. M. & Nais, J. 2004. Mitochondrial DNA sequences reveal the photosynthetic relatives of Rafflesia, the world's largest flower. PNAS 101(3): 787-792.

Davies, C.C. 2008. Floral Evolution: Dramatic size change was recent and rapid in the world's largest flowers. Current Biology 18(23): 1102-1104.

Heywood, V.H. 2007. Mitrastemonaceae. In: Heywood, V.H., R.K. Brummitt, A. Culham & O. Seberg (eds). Flowering plant families of the world. pp.215-216. Kew: Royal Botanic Gardens, Kew.

Matuda, E. 1947. On the genus Mitrastemon. Bulletin of the Torrey Botanical Club 74(2): 133-141.

Meijer, W. 1933. Rafflesiaceae. In: Kubitzki, K. (ed.). Families and genera of vascular plants. Volume 2. Flowering plants. Dicotyledons. pp557-563. Springer-Verlag, Berlin.

Nickrent, D.L., Blarer, A.,Qiu, Y.L. Romina, Vidal-Russell, R. & Anderson, F.E. 2004. Phylogenetic inference in Rafflesiales: the influence of rate heterogeneity and horizontal gene transfer, BMC Evolutionary 4: 40.

Standley, P. C. & Steyermark, J. A. 1946. Flora of Guatemala. Fieldiana, Botany 24(4): 101-104.

Mitrastemonaceae Makino appears in other Kew resources:

First published in Bot. Mag. (Tokyo) 25: 252. 1911 [20 Dec 1911] (1911)

Accepted by

  • APG IV (2016) http://dx.doi.org/10.1111/boj.12385

Sources

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

Neotropikey
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