''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 i ...

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 only 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 foun ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

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

Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...

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 considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

and is the only species in the Stylidiaceae native to the

Americas The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...

. 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 In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

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 nucleot ...

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