''Lyallia kerguelensis'', commonly called the lyallia cushion (''coussin de lyallia'' in French), is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

flowering A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism ...

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 ...

in the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''Lyallia'' of the

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

Montiaceae Montiaceae are a family of flowering plants, comprising about 14 genera with about 230 known species, ranging from small herbaceous plants to shrubs. The family has a cosmopolitan distribution. The family Montiaceae was newly adopted in the APG ...

. It is sometimes placed in the Hectorellaceae or the Portulacaceae. The generic name honours British botanist and naval officer

David Lyall David Lyall (1817–1895) MD, RN, FLS, was a Scottish botanist who explored Antarctica, New Zealand, the Arctic and North America and was a lifelong friend of Sir Joseph Hooker. He was born in Auchenblae, Kincardineshire, Scotland on 1 June 181 ...

who served as assistant surgeon on HMS ''Terror'' on the Antarctic exploring expedition led by

James Clark Ross Sir James Clark Ross (15 April 1800 – 3 April 1862) was a British Royal Navy officer and polar explorer known for his explorations of the Arctic, participating in two expeditions led by his uncle John Ross, and four led by William Edwa ...

from 1839 to 1843. Lyall was a friend and colleague of describer

Joseph Dalton Hooker Sir Joseph Dalton Hooker (30 June 1817 – 10 December 1911) was a British botanist and explorer in the 19th century. He was a founder of geographical botany and Charles Darwin's closest friend. For twenty years he served as director of ...

on the expedition when the type material was collected. The specific epithet refers to the type locality.

Description

''Lyallia kerguelensis'' is a

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 wid ...

herb. It forms round cushions, usually 200–400 mm across, but occasionally up to 1 m in diameter. Its closest relative is the similar cushion plant '' Hectorella caespitosa'' which is found in alpine areas of the South Island of

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 ...

.Wagstaff & Hennion (2007).

Distribution and habitat

The species is

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 else ...

to the

subantarctic The sub-Antarctic zone is a region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° and 60° south of the Equator. The subantarctic region includes many islands ...

Kerguelen Islands, part of the French Southern and Antarctic Lands in the southern

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by t ...

. It grows in small populations on moraines and

fellfield A fellfield or fell field comprises the environment of a slope, usually alpine or tundra, where the dynamics of frost (freeze and thaw cycles) and of wind give rise to characteristic plant forms in scree interstices. Soil dynamics The freeze-thaw ...

s, from the sea shore to about 300 m above sea level, and can live for at least 16 years.

References

Notes

Sources

* * * Montiaceae Flora of the Kerguelen Islands Monotypic Caryophyllales genera Plants described in 1847 Cushion plants {{Caryophyllales-stub