''Pycnosorus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of six species of plants in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

. Commonly known as billy buttons or drumsticks, they are annual or

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

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 Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds ...

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 Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

") 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'' 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 Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

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 The Australian Plant Census (APC) provides an online interface to currently accepted, published, scientific names of the vascular flora of Australia, as one of the output interfaces of the national government Integrated Biodiversity Information Syst ...

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