Propolis samples from Kangaroo Island, South Australia, were investigated for chemical constituents using high-field nuclear magnetic resonance spectral profiling. A type of propolis was found containing a high proportion of prenylated hydroxystilbenes. Subsequently, the botanical origin of this type of propolis was identified using a beehive propolis depletion method and analysis of flora. Ligurian honey bees, Apis mellifera ligustica Spinola, were found to produce propolis from resin exuded by the Australian native sedge plant Lepidosperma sp. Montebello (Cyperaceae). The plants, commonly known as sword sedge, were found to have resin that matched with the propolis samples identified as the most abundant propolis type on the island containing C- and O-prenylated tetrahydroxystilbenes (pTHOS) in addition to a small amount of prenylated p-coumarate. The isolation of five pTHOS not previously characterized are reported: (E)-4-(3-methyl-2-buten-1-yl)-3,40,5-trihydroxy-30-methoxystilbene, (E)-2,4-bis(3-methyl-2-buten-1-yl)-3,30,40,5-tetrahydroxystilbene, (E)-2-(3-methyl-2-buten-1-yl)-3-(3-methyl-2-butenyloxy)-30,40,5-trihydroxystilbene, (E)-2,6-bis(3-methyl-2-buten-1-yl)-3,30,5,50-tetrahydroxystilbene and (E)-2,6-bis(3-methyl-2-buten-1-yl)-3,40,5-trihydroxy-30-methoxystilbene. A National Cancer Institute 60 human cell line anticancer screen of three of these compounds showed growth inhibitory activity. The large Australasian genus Lepidosperma is identified as a valuable resource for the isolation of substances with medicinal potential.

We investigated the limits of Lepidosperma congestum R.Br. and a putative new species of Lepidosperma Labill. from Victoria and South Australia. Phenetic analyses (flexible UPGMA agglomerative hierarchical fusion and semi-strong hybrid multidimensional scaling) were conducted on a dataset derived from morphological characters scored from herbarium material. The results of our analyses supported the recognition of a new species, which we describe here as Lepidosperma hispidulum G.T.Plunkett, J.J.Bruhl & K.L.Wilson. Our results clarified the differences among L. congestum, L. laeve R.Br. and L. hispidulum, the first two of which have often been misidentified. We also discuss the distribution, habitat and conservation status of L. hispidulum.

This thesis investigates the systematics and ecology of the eastern Australian species of Lepidosperma Labill. (Cyperaceae). The investigation sets the c. 33 eastern Australian species in context with the c. 76 described species found throughout Australia, New Zealand, New Caledonia and southern Asia.

We investigated the status of a putative new species of Lepidosperma from the mountains of south-western Tasmania using phenetic analysis on morphological/anatomical data (Chapter 2). Our results support the recognition of this species, here described as Lepidosperma monticola G.T.Plunkett & J.J.Bruhl. The distribution, habitat and conservation status are discussed.

The thickened and persistent perianth members of Lepidosperma diaspores are generally assumed to form a unique type of elaiosome. We tested whether these perianth members provide a food reward and improve the removal of diaspores by ants (Chapter 3). We measured the physical traits of diaspores, the lipid and fatty acid composition of the perianth, and the relative attractiveness to ants of the perianth of some species of Lepidosperma. We found that diaspores of Lepidosperma show traits consistent with myrmecochory, particularly the lipid content of perianth material and the presence of oleic acid in fruit and perianth of Lepidosperma. Diaspores of Lepidosperma and Acacia were equally attractive to ants. We concluded that the perianth members act as an elaiosome that provides a lipid-rich food reward and contains known ant attractants.

Lepidosperma viscidum R.Br. forms a highly diverse complex distributed across southeastern Australia. We utilised multiple sources of data to delimit species: phenetic analyses using morphology/anatomy; novel resin metabolic fingerprinting; and phylogenetic analyses via nuclear ribosomal (ETS) and chloroplast (trnL-F) gene sequencing (Chapter 4). Our results give strong support for a more condensed circumscription of L. viscidum s.s., and the recognition of at least three undescribed species.

Lepidosperma is taxonomically difficult for non-specialists and specialists; delimitation of many species of Lepidosperma has long been problematic. We used nuclear ribosomal (ETS) and chloroplast (trnL-F) gene sequence data from over 300 specimens for phylogenetic analysis and to test known and putative species. Overall, the analysis provides good resolution above the level of species, but little support for higher relationships within the genus. We found that most described species are well supported but the L. laterale R.Br. clade in particular continues to be unresolved. The analyses also provided support for the recognition of at least four further undescribed species and highlights avenues for future work.