Ptilotus

Plants in the genus Ptilotus are annual or perennial herbs or small shrubs, many covered with soft hairs. The leaves are arranged alternately, sometimes on branches and/or in a rosette at the base. The flowers are bisexual and borne in compact spherical to oval or cylindrical spikes, each flower with a membranous bract and two bracteoles at the base. There are five, equal, hairy, linear tepals and five stamens, sometimes up to three stamens reduced to sterile staminodes, fused into a cap surrounding the ovary. The fruit is a nut or utricle, surrounded by the remains of the perianth.^[3][4][5]

The genus Ptilotus was first formally described in 1810 by Robert Brown in his Prodromus Florae Novae Hollandiae.^[6][7] The genus name means 'winged', particularly 'soft winged'.^[8]

In family-level phylogenetic studies, Ptilotus has been placed within a clade informally known as the 'aervoids'.^[9] It has been resolved as monophyletic and is closely related to Aerva Forssk.^[10][11]

Most species of Ptilotus occur in arid parts of Western Australia,^[5][10][12] but there are species in the Northern Territory, Queensland, South Australia, New South Wales, Victoria and Tasmania.^[13]

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  Ptilotus exaltatus Nees
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  Ptilotus obovatus (Gaudich.) F.Muell.
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  Ptilotus eriotrichus (Gaudich.) F.Muell.
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  Ptilotus stirlingii (Lindl.) F.Muell. subsp. stirlingii
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  Ptilotus declinatus Nees
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  Ptilotus fusiformis (R.Br.) Poir.
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  Ptilotus nobilis (Lindl.) F.Muell
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  Ptilotus appendiculatus Benl
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  Ptilotus latifolius R.Br.
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  Ptilotus drummondii (Moq.) F.Muell.
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  Ptilotus xerophilus T.Hammer & R.W.Davis
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  Ptilotus rotundifolius (F.Muell.) F.Muell.