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Hansjörg Eichler Scientific Research Fund – Report

Phylogeny, biogeography and pollination ecology in Stylidium section Stylidium

Elisa Raulings, School of Botany, University of Melbourne, Grattan St. Parkville 3052

Hansjörg Eichler Research Grant- Field Work Report

The Australasian family Stylidiaceae is distinguished in having the stamens fused to the style to form a column, of which the apex bears a bilobed terminal stigma and two lateral anthers. In the Triggerplant genus Stylidium this column is irritable, and upon stimulation provides one of the fastest and most spectacular movements among plants

Stylidium comprises approximately 200 species of annual and perennial herbs, the majority of which occur in southwestern Australia. Based on herbarium and glasshouse specimens, Mildbraed (1908) undertook a classification of Stylidium into sub genera and sections based on vegetative characters such as habit, calyx shape, placentation, leaf shape and anatomy.

Mildbraed's (1908) Stylidium section Stylidium (=Lineares) contains about 26 species distributed from the Hawkesbury and Narrabeen sandstones of NSW (S. lineare and S. productum), the Grampians (S. soboliferum), Kangaroo Island (S. tepperianum) and throughout the southwest of western Australia, with a little-known species from Central Australia (S. inaequipetalum). Mildbraed (1908) defined this section on morphological and anatomical characters, but descriptions of new taxa and an improved understanding of characters has brought the boundaries of this section into question. My research aims to test the monophyly and elucidate the phylogeny of Stylidium section Stylidium by undertaking a cladistic analysis of morphological characters. Using the phylogenetic tree as a basis, I intend to map floral characters on the tree to construct a hypothesis of floral evolution, and focus on the Stylidium graminifolium complex to study pollination ecology and chromosomal variation in relation to speciation.

The Hansjörg Eichler Award of $500 enabled me to undertake a field trip from Melbourne to Kangaroo Island to collect flowers in 70% ethanol and fresh specimens for chromosome counts. I collected Stylidium soboliferum from the Grampians and S. tepperianum from the cliffs of Kangaroo Island. I have been able to score several floral and vegetative characters from these specimens, and compare the morphology to species in the west. The collection of flowers in ethanol has greatly improved the accuracy of my scoring, particularly with respect to throat appendages and labella detail.

I was fortunate enough to collect ephemeral Stylidium species throughout Victoria and South Australia: S. despectum, S. beaugleholei, S. inundatum, S. calcaratum and S. perpusillum. These specimens germinate after rainfall and grow in swampy areas throughout southern Australia. Ephemeral species have not been recently collected from the eastern states, and their preservation in ethanol is vital so that detailed floral characters can be examined. In conjunction with Juliet Wege (University of Western Australia), the morphology and distribution of these species from the east to west of Australia will be examined.

I am very honoured to have been among the first recipients of the Hansjörg Eichler Award, and to have been given the opportunity to collect these important species of Stylidium. I wish to express my sincere appreciation to the Australian Systematic Botany Society for awarding me the scholarship and thereby enabling me to improve the quality of my research. I am also grateful to Nicole Middleton for her assistance in collecting plants from precarious cliffs and muddy swamps, and to my supervisor, Pauline Ladiges, for covering my other field trip expenses.

References

Mildbraed, J. (1908). Stylidiaceae. In Engler, E. (ed), Das Pflanzenreich IV, no. 278 (Verlag H.R.Englemann): Weinheim, Germany.

 

Published in Australian Systematic Botany Society Newsletter 95: 26 (June 1998)


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