Pycnosorus globosus, Billy Buttons, is a dense soft-wooded ground cover with a spread of at least 50 cm, with flowering stems to 120 cm tall. This species appears somehwat similar to the related Chrysocephalum apiculatum.
It has a widespread natural distribution, growing only in the inland areas of NSW, on the western slopes to the far western plain, and over most of this terrain – west of areas such as Albury, Tamworth and Glen Innes; right out to the north-west of the state; much less found in the south-west. It extends into Victoria, where it grows between Wodonga and Mathoura and south-west to Horshame and Bendigo. It extends into Queensland, growing between Warwick-Toowoomba and areas near Cunnamulla and north to near Mitchell. It is found in South Australia between Port August and Adelaide (north of Adelaide) and further north past Hawker. There are some additional small-patch disjunct records in the middle of South Australia and along the South Australia / Queensland border.
It is found often in dry sclerophyll woodland and open shrubby and grassland patches – often in moist depressions on sandy-clay soils. It is often seen on vegetated road verges.
Pycnosorus spp. have simple basal and flowering-stem (cauline) leaves, arranged alternately. In this species, basal leaves do not persist long; both basal and cauline leaves are linear, to 30 cm long (often much shorter), by 1.2 cm wide, with prominent longitudinal veins, white-grey in colour due to dense hairs; with an overall soft texture.
Pycnosorus spp. are in the daisy family and therefore produce flowers in an inflorescence called a capitulum (often referred to as a ‘head’). This is an evolved structure where a large number of modified flowers (florets) are grouped together to look like one flower. The Sunflower (Helianthus annuus) would be the most grandiose example. The ‘petals’ of the capitula are actually ‘ray florets’ which contain a floret hidden inside the elongated ‘petal’ which is actually an extended limb of the corolla tube called a ligule. The disc in the middle of the capitulum (often yellow or orange in colour) consists of very small ‘disc florets’ which have a small 3-5 lobed corolla tube with stamens and a carpel.
In this genus, ray florets are bascially absent – only disc florets form the head (which can be the case in many daisy-genera), which are surrounded by an involucre (overlapping rows) of papery bracts and with florets arranged around a globular head. (This genus gets very complicated in that the globose heads are thought to be a cluster of separate partial heads). In this species, the globular heads are raised solitarily on peduncles to 120 cm long, about 35 mm in diameter, consisting of many small florets, yellow to golden yellow in colour, usually produced in spring and summer).
The fruit is an achene; with a cuneate shape to 3 mm long and 1 mm wide with a pappus of hairs/bristles to 5 mm long.
This is a very nice addition to any garden. It will add very attractive splashes of golden yellow. They are quite striking in flower.
Remove spent flowers to encourage more blooms. A Billy Buttons in full flower is a sight to behold in the garden. Flowers may be use in dry flower arrangements. Billy Buttons would be at home in cottage gardens, rockeries or as a foreground plant in native gardens.
Best planted in an open sunny spot with reasonable drainage. Do not mulch too heavily. Best planted in the foreground.
Propagate from cuttings. As with most of this family cuttings produce roots rapidly. Seed can also be trialled
The species was previously known as Craspedia globosa and was renamed in 1992.
This species would regenerate readily from seed after fire.
Pycnosorus is a genus of 6 species – endemic to Australia. NSW currently has 4 species.
Pycnosorus – from Ancient Greek – puknos (πυκνός) – meaning “thick”, “dense” or “compact” and soros “quantity” or “heap” – referring to the dense globular flower heads.
globosus – Latin – meaning globose or “rounded” – also referring to the flower heads.
This species is not considered to be at risk of extinction in the wild.
NSW Flora Online (PlantNET) – Pycnosorus globosus profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Pycnosorus~globosus
Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.
Gardening with Angus – Pycnosorus globosus profile page https://www.gardeningwithangus.com.au/pycnosorus-globosus-billy-buttons/