Leptorhynchos Less. is a small genus of annual or perennial herbs in the daisy family Asteraceae (tribe Gnaphalieae), comprising roughly ten species all endemic to Australia. The genus was described by the German botanist Christian Friedrich Lessing in the nineteenth century.
Plants are covered with glandular or non-glandular hairs that range from short and fine to long and woolly-cobwebby. The flower heads (capitula) are borne singly at the tips of long leafless scapes or arranged in leafy corymbs, and are campanulate to almost hemispherical in shape. The involucre is built of many overlapping series of bracts: the outermost are much reduced, the innermost are long and usually claw-like, and all bear scarious (papery) tips. The receptacle is convex, naked, and pitted. Most florets are bisexual and five-merous, while a small number of outer florets are female and three- or four-merous; corollas are tubular and considerably longer than the involucre. Achenes are oblong or sickle-shaped, slightly compressed or obscurely four-angled, and may taper to a slender beak; the pappus consists of a few to many slightly fused bristles that are barbellate or brush-like at the tip.
The genus is distributed across all Australian states except the Northern Territory. Common names for several species include "buttons" or "button immortelle," reflecting the neat, button-like appearance of the heads. Well-known members include Leptorhynchos squamatus (scaly buttons) and Leptorhynchos tetrachaetus (beauty buttons). The genus is placed within Asteraceae alongside other predominantly Southern Hemisphere button daisies.
Etymology
The genus name Leptorhynchos is derived from the Greek leptos (slender, fine) and rhynchos (beak or snout), referring to the slender beak that terminates the achenes in some species.
Distribution
All species of Leptorhynchos are endemic to Australia, occurring across all states except the Northern Territory. The genus is represented by approximately ten accepted species, with occurrence records concentrated in southern and eastern Australia.
Taxonomy Notes
Leptorhynchos was described by Christian Friedrich Lessing (author abbreviation Less.) and is placed in the family Asteraceae (also referred to by its conserved synonym Compositae). GBIF records 19 infraspecific and specific descendants. The genus belongs to the tribe Gnaphalieae, the everlasting or paper daisy group within Asteraceae.
