Jan FEB Mar 23 2008 2009 2010 1 capture 23 Feb 09 - 23 Feb 09

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Section Juncotypus

Systematic Studies in Juncus L. (Juncaceae)

John Hodgon

The project is being undertaken as a fulltime PhD at the University of New England, Australia under the supervision of A/Prof. Jeremy Bruhl and A/Prof. Karen Wilson of the Royal Botanic Gardens, Sydney.

Project details

Two subgenera and ten sections are currently recognised within Juncus (Kirschner et al. 1999). Section Juncotypus (previously subgenus Genuini; Kirschner et al. 1999) has about 70 species found mainly in cool temperate zones of the Northern and Southern Hemispheres with a few species found at high altitude in the tropics. There are about 40 currently recognised species in Australia (Wilson et al. 1994).  Putative hybrids between species within the section are common (Wilson et al. 1994; Edgar 1964). Several species complexes exist within the section, e.g. J. polyanthemus, although the limits of these complexes have yet to be tested. 

    To date no detailed systematic study, based on molecular and/or non-molecular data, has been undertaken to determine the phenetic and/or phylogenetic relationships among taxa in Juncus section Juncotypus. The status and origin of reported hybrids between species of section Juncotypus has also not yet been determined. Diffuse centromeres have been reported in the genus Luzula but it has not been established if they occur in other genera of Juncaceae (Greilhuber 1995). 

The project will involve field studies, assessment of characters previously used, investigation and development of novel characters, automated databasing techniques, and phenetic and cladistic analyses. Data sources to be explored include floral, fruit and vegetative morphology, anatomy, palynology, embryology, cytology, and molecular data (ISSR and gene sequences).  

The aims of the project are to investigate and determine:      

• Taxon limits within section Juncotypus, including testing the subsectional groups of Buchenau (1906), i.e. the laeves ('smooth culms') and valleculati ('strongly-ribbed culms') groups.
• Taxon limits within selected species complexes in section Juncotypus, including J. polyanthemus, J. subsecundus and J. laeviusculus.
• The status of suspected and/or reported hybrids and elucidation of their origins.
• Reconstruct phylogeny and test monophyly of the sections and subgenera of Juncus.
• The occurrence of diffuse centromeres in the genus Juncus.

References

Albrecht, D. E. (1994). Juncaceae. In 'Flora of Victoria'. Vol. 2. (Eds. N. G. Walsh &T. J. Entwisle) pp. 197-238. (Inkata Press: Melbourne.)

Buchenau, A. (1906). Juncaceae. In Das Pflanzenreich. IV, 36 (Heft 25). (Ed. A. Engler) pp 1-284.

Edgar, E. (1964). The leafless species of Juncus in New Zealand. New Zealand Journal of Botany 2, 177-204.

Greilhuber J (1995) Chromosomes of the monocotyledons. In 'Monocotyledons: Systematics and Evolution'. (Eds PJ Rudall, PJ Cribb, DF Cutler and CJ Humphries). (Royal Botanic Gardens: Kew)

Kirschner, J., Novara, L. J., Novikov, V. S., Snogerup, S., and Kaplan, Z. (1999). Supraspecific division of the genus Juncus (Juncaceae). Folia Geobotanica 34, 377-390.

Wilson, K. L., Johnson, L. A. S., and Bankoff, P. (1993). Juncus. In 'Flora of New South Wales'. Vol. 4. (Ed. G. Harden.) pp. 266-289. (UNSW Press: Kensington.)