Agastachys odorata, commonly known as the white waratah, is the sole member of the genus Agastachys in the protea family. It is an evergreen shrub to small tree and is endemic to the heaths and button grass sedgelands of western Tasmania. It occurs most often in moist heath and scrub and occasionally in the alpine regions, but generally prefers well-drained but poor soils. It can grow in some rainforests where it forms a small tree but is normally a shrub in all other situations. The heaviest concentrations are along the island's south coast. Its leaves are dark green, hairless and almost succulent. Masses of white flowers are produced in erect spikes from the ends of the branches. Measuring 8 to 12 cm high, they appear in January and February.
Scottish botanist Robert Brown described Agastachys odorata in 1810, and it still bears its common name today. The genus only contains the single species, and has been grouped with the Australian genera Agastachys, Symphionema and New Caledonian genera Beauprea and Beaupreopsis in the subtribe Cenarrheninae by Johnston and Briggs in 1975. However, Peter H. Weston and Nigel Barker reviewed the suprageneric relationships of the Proteaceae in 2006, using molecular and morphological data. In this scheme Agastachys and Symphionema are sister taxa in a clade which diverged early from the main lineage, and they are classified in their own subfamily Symphionematoideae.
- "Agastachys odorata R.Br.". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government.
- "Agastachys R.Br.". Flora of Australia Online. Department of the Environment and Heritage, Australian Government.
- J.B. Kirkpatrick; Sue Backhouse (2007). Native Trees of Tasmania, Seventh Edition Completely Revised. Sandy Bay, Tasmania: Pandani Press. ISBN 0-646-43088-2.
- University of Tasmania. "Key to Tasmanian Dicots".
- "Agastachys odorata R.Br.". Flora of Australia Online. Department of the Environment and Heritage, Australian Government.
- "Cenarrheninae L.A.S.Johnson & B.G.Briggs". Flora of Australia Online. Department of the Environment and Heritage, Australian Government.
- Weston, Peter H.; Barker, Nigel P. (2006). "A new suprageneric classification of the Proteaceae, with an annotated checklist of genera" (PDF). Telopea. 11 (3): 314–344. Archived from the original (PDF) on 2009-10-02.
- Schahinger, R.; Rudman T.; Wardlaw, T. J. (2003). "Conservation of Tasmanian Plant Species & Communities threatened by Phytophthora cinnamomi. Strategic Regional Plan for Tasmania" (PDF). Hobart, Tasmania: Department of Primary Industries, Water and Environment. pp. (appendix). Archived from the original (PDF) on 1 April 2012. Retrieved 17 September 2012.