''Pycnosorus'' is a genus of six species of plants in the family Asteraceae. Commonly known as billy buttons or drumsticks, they are annual or perennial

herbs In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...

or small shrubs with a cylindrical to spherical head of up to 200 daisy-like "flowers". Each "flower" is a pseudanthium consisting of between three and eight florets surrounded by

bract In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...

s. The

petal Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...

s are joined to form a small tube and the florets with their surrounding bracts are yellow or golden-yellow.

Description

Plants in the genus ''Pycnosorus'' are annual or perennial herbs, with leaves decreasing in size up the stem, those at the base withering first. The flowers are arranged in oval to more or less spherical heads of 40 to 200 flower-like partial heads. Each partial head consists of three to eight small flower-like "florets". The florets and the

s which surround them are yellow or golden in colour. Each flower has five petals joined to form a tube. After pollination the flowers become silky

achene An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and indehiscent (they do not ope ...

s with a ring of feathery bristles. Plants in the closely related genus '' Craspedia'' are also known by the common name "billy buttons" but have their flowers on small stalks rather than attached directly to the

receptacle Receptacle may refer to: Biology * Receptacle (botany), a plant anatomical part * Seminal receptacle, a sperm storage site in some insects Electrical engineering * Automobile auxiliary power outlet, formerly known as ''cigarette lighter recep ...

(" sessile") as in ''Pycnosorus''. There is some evidence that the two genera may in fact be

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

Taxonomy and naming

The genus was first formally described in 1837 by George Bentham and the description was published in '' Enumeratio plantarum quas in Novae Hollandiæ ora austro-occidentali ad fluvium Cygnorum et in sinu Regis Georgii collegit Carolus Liber Baro de Hügel ''.Tropicos, ''Pycnosorus'' Benth.
/ref> Bentham nominated ''

Pycnosorus globosus ''Pycnosorus'' is a genus of six species of plants in the family Asteraceae. Commonly known as billy buttons or drumsticks, they are annual or perennial herbs or small shrubs with a cylindrical to spherical head of up to 200 daisy-like "flowers" ...

'' as the

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * Ty ...

species. The genus name (''Pycnosaurus'') is derived from the Ancient Greek words ''pyknos'' meaning "dense" or "thick" and ''soros'' meaning "heap". The following is a list of species of ''Pycnosorus'' accepted by the Australian Plant Census as at 30 November 2019:

Distribution and habitat

All six species of ''Pycnosorus'' are endemic to Australia and there are species in all states except Tasmania. Most species grow in heavy, often rocky soils.

References

{{Taxonbar, from=Q11701425 Endemic flora of Australia Gnaphalieae Asteraceae genera