Isopogon is a genus of roughly forty species of flowering shrubs in the family Proteaceae (order Proteales), endemic to Australia. They are commonly known as conesticks, conebushes, coneflowers, or drumsticks — names that all refer to the distinctive woody, cone-like fruiting structures that persist on the plant after flowering.
Plants in the genus are erect or prostrate shrubs bearing rigid, usually compound leaves that are deeply divided into flat or cylindrical lobes; simple leaves are rare. Flowers are bisexual and radially symmetrical, arranged in dense conical or spherical spikes at the ends of branches and typically subtended by bracts. As a flower matures, the tepals spread outward while the lower portion persists until the developing fruit expands. The individual fruits are small hairy nuts whose enclosing bracts eventually fall away to release them; collectively the fruits fuse into a woody, cone-like to roughly spherical head — the structure that gives the genus its popular common names. Isopogon species share a base chromosome number of 13 (haploid).
The genus was first formally described in 1809 by Joseph Knight in his work On the cultivation of the plants belonging to the natural order of Proteeae, narrowly pre-empting a parallel publication of the same name by the botanist Robert Brown. All known species are restricted to Australia, making Isopogon one of the larger strictly Australian genera within the Proteaceae.
Etymology
The genus name Isopogon derives from Greek isos (equal) and pogon (beard), referring to the uniform feathery or hairy appendages on the fruits. The common names conesticks, conebushes, and drumsticks all refer to the hard, persistent woody cone formed by the fused fruiting heads.
Distribution
All species of Isopogon are endemic to Australia. The genus is particularly species-rich in the Southwest Australian Floristic Region, one of the world's recognised biodiversity hotspots, with a smaller number of species occurring in eastern Australia.
Taxonomy Notes
The genus was first formally described in 1809 by Joseph Knight in On the cultivation of the plants belonging to the natural order of Proteeae, pre-empting Robert Brown's independent publication of the same name in his On the natural order of plants called Proteaceae. This dual publication history makes the authorship somewhat contested in early botanical literature. The Australian Plant Census (as of November 2020) is the current authority for accepted species, subspecies, and varieties; at that date two recently described species (I. autumnalis, 2019; I. nutans, 2020) had not yet been formally accepted.
