Botanic Gardens Trust, Sydney, Australia

Indigofera

Revision of the genus Indigofera (Fabaceae) in Australia

Dr Peter Wilson - Senior Research Scientist 

As part of an on-going study of the genus Indigofera, two further species have been described and submitted for publication. The first of these species occurs along a region that runs diagonally from the White Mountains west of Townsville to the Eromanga district in south-western Queensland, a distance of around 900 km. Over this range, this species shows a considerable degree of leaf variation, showing differences in leaflet number (ranging from 7-11 leaflets in the south-west to 19-23 leaflets at the north-east end of the range) and indumentum. However, the floral morphology remains more-or-less constant: the flowers are pink and have a relatively long keel. This species has previously been confused with Indigofera leucotricha, which does occur in the far south-west of the state, but that species has leaflets with cuneate apices and a shorter, stouter fruit.

The second species occurs in western Queensland and neighbouring areas of the Northern Territory north of the McDonnell Ranges. This species, has long been included in Indigofera brevidens, but that name is one of the most widely misapplied names in Australia. The new species differs most noticeably from I. brevidens by having smaller flowers that are red (rather than pink) and by its somewhat spinescent stipules. 

A precursor paper has also been published for the new edition of the Flora of South Australia. This included one new species, Indigofera cornuligera, with two subspecies, plus a new subspecies of I. australis. These papers were co-authored by former research assistant Ross Rowe (now with Department of Sustainability, Environment, Water, Population and Communities, Canberra).

A revised treatment of the Indigofera, and the related genus Indigastrum, in South Australia is now available online in the new Flora format.

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Indigofera 'erubescens' showing its small red flowers.

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Indigofera 'queenslandica' showing flowers with relatively long petals.

Photos: Peter Wilson