''Phyllachne'' is a genus of four

cushion plant A cushion plant is a compact, low-growing, mat-forming plant that is found in alpine, subalpine, arctic, or subarctic environments around the world. The term "cushion" is usually applied to woody plants that grow as spreading mats, are limited in ...

species in the family

Stylidiaceae The family Stylidiaceae is a taxon of dicotyledonous flowering plants. It consists of five genera with over 240 species, most of which are endemic to Australia and New Zealand. Members of Stylidiaceae are typically grass-like herbs or small shrub ...

. Of the four species, two are

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

, while '' P. colensoi'' is also native to

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

and '' P. uliginosa'' is entirely endemic to southern

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

and is the only species in the Stylidiaceae native to the

Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

. The movement of ''P. colensoi'' to colonize Tasmania is a relatively recent move. Molecular studies group ''P. colensoi'', '' P. clavigera'', and '' P. rubra'' together in one

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

with ''P. uliginosa'' in the sister clade. Based on

molecular clock The molecular clock is a figurative term for a technique that uses the mutation rate of biomolecules to deduce the time in prehistory when two or more life forms diverged. The biomolecular data used for such calculations are usually nucleoti ...

data of the ''rbcL'' gene, it is estimated that ''P. uliginosa'' last shared a common ancestor with the New Zealand clade about 6 million years ago.Wagstaff, S.J. and Wege, J. (2002)
Patterns of diversification in New Zealand Stylidiaceae
''American Journal of Botany'', 89(5): 865-874.Good, R. (1925). On the geographical distribution of the Stylidiaceae. ''New Phytologist'', 24(4): 225-240.

References

Stylidiaceae Asterales genera {{Stylidiaceae-stub