Journal of Plant Research

, Volume 121, Issue 3, pp 271–278

Taxonomic status of Monotropastrum humile, with special reference to M. humile var. glaberrimum (Ericaceae, Monotropoideae)

  • Hirokazu Tsukaya
  • Jun Yokoyama
  • Ryoko Imaichi
  • Hideaki Ohba
Regular Paper

DOI: 10.1007/s10265-008-0157-9

Cite this article as:
Tsukaya, H., Yokoyama, J., Imaichi, R. et al. J Plant Res (2008) 121: 271. doi:10.1007/s10265-008-0157-9

Abstract

Taxonomic treatment of the achlorophyllous monotropoid plant Monotropastrum humile is still unclear and confusing because of the lack of detailed morphological analyses and molecular phylogeny. In particular, the taxonomic status of a glabrous variety, M. humile var. glaberrimum, is under debate. Our detailed examination of the morphological characteristics of living plants revealed that M. humile var. glaberrimum can be easily distinguished from the putative conspecific taxon M. humile var. humile by characteristics not previously recognized, namely the shape and color of the floral disc. Most morphological features characterizing Cheilotheca were also found in M. humile var. glaberrimum. Moreover, there was considerable nucleotide differentiation in the internal transcribed spacer (ITS)2 sequences of M. humile var. humile and var. glaberrimum. Molecular analysis of the phylogenetic relationship of M. humile var. humile, var. glaberrimum, and other monotropoids using ITS2 sequences showed that two varieties of M. humile formed a monophyletic clade with a member of a different genus, Monotropa L., but obvious phylogenetic relationships among these three taxa were not obtained. Thus we conclude that Monotropastrum humile var. glaberrimum should be treated as a distinct species. However, the generic affiliation of M. humile var. glaberrimum could not be determined because of its intermediate character state combination and the insufficient characterization of related species. We strongly suggest that Monotropastrum as a whole needs re-evaluation.

Keywords

Epiparasitic plantFloral discInternal transcribed spacerMonotropa unifloraMonotropastrum humilePhylogenySystematics

Copyright information

© The Botanical Society of Japan and Springer 2008

Authors and Affiliations

  • Hirokazu Tsukaya
    • 1
    • 2
  • Jun Yokoyama
    • 3
  • Ryoko Imaichi
    • 4
  • Hideaki Ohba
    • 5
  1. 1.Graduate School of ScienceUniversity of TokyoBunkyo-ku, TokyoJapan
  2. 2.National Institute for Basic BiologyMyodaiji-choJapan
  3. 3.Department of Biology, Faculty of ScienceYamagata UniversityYamagataJapan
  4. 4.Faculty of ScienceJapan Women’s UniversityTokyoJapan
  5. 5.University MuseumUniversity of TokyoTokyoJapan