Key to propagules of selected weedy Asteraceae (daisy or sunflower family)

Description

A key to the propagules or fruits of 43 biosecurity-relevant species of the daisy or sunflower family Asteraceae. It was produced by CSIRO scientist Alexander Schmidt-Lebuhn at the Australian National Herbarium (CANB) in collaboration with and through funding from the Department of Agriculture and Water Resources.

Usage

Note that not all species of Asteraceae can be differentiated based on their propagules alone. When using the key, consider the following: Is the pappus perhaps not naturally absent or deciduous in this species but merely broken off due to rough handling? Often remnants at the upper end of the fruit give an indication. Is the fruit sufficiently mature? The colour of immature fruits can be misleading. To see the surface ornamentation of pappus bristles, a dark background can be helpful. Very useful first-pass characters are the surface colour of the fruit, especially if black, its dimensions, and the length of the pappus. Note also that selecting some characters, in particular pappus type and presence of longitudinal ribs, will make additional characters appear to describe these structures in more detail.

Acknowledgements

The author thanks Gertraud Norton (DAWR) for support, discussions, advice and photos used in the key, Lindy Cayzer for support and helpful discussions, Brook Clinton for additional photos, David Albrecht for play-testing the key, and the herbaria GOET, HBG, K, and MEL for making fruiting herbarium specimens available for study.