''Acaena'' is a

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 ...

of about 60 species of mainly

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...

, creeping herbaceous

perennial plants 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 widel ...

and subshrubs in the family Rosaceae,

native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and entert ...

mainly to the Southern Hemisphere, notably New Zealand, Australia and South America, but with a few species extending into the Northern Hemisphere, north to Hawaii ('' A. exigua'') and California ('' A. pinnatifida''). The leaves are alternate, long, and pinnate or nearly so, with 7–21 leaflets. The

flower 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 mechani ...

s are produced in a tight globose nflorescence in diameter, with no petals. The

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

is also a dense ball of many

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

s; in many (but not all) species the seeds bear a barbed arrowhead point, the seedhead forming a burr which attaches itself to animal fur or feathers for dispersal. Several ''Acaena'' species in New Zealand are known by the common name bidibid. The word is written variously ''bidi-bidi'', ''biddy-biddy'', ''biddi-biddi'', ''biddi-bid'' and a number of other variations. These names are the English rendition of the original Māori name of ''piripiri''. The plant is also called the New Zealand burr. The species ''

Acaena microphylla ''Acaena microphylla'', the bidibid or piripiri, and outside New Zealand, New Zealand-bur, is a small herbaceous, prostrate perennial flowering plant in the rose family Rosaceae, native to both the North and South Islands of New Zealand. The ...

'' has gained the

Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr (Nor ...

's Award of Garden Merit.

Etymology

The generic name ''Acaena'' is derived from the Greek "akaina" (thorn), referring to the spiny

hypanthium In angiosperms, a hypanthium or floral cup is a structure where basal portions of the calyx, the corolla, and the stamens form a cup-shaped tube. It is sometimes called a floral tube, a term that is also used for corolla tube and calyx tube. It ...

Species

, Plants of the World Online accepted the following species: *''

Acaena agnipila ''Acaena'' is a genus of about 60 species of mainly evergreen, creeping herbaceous perennial plants and subshrubs in the family Rosaceae, native mainly to the Southern Hemisphere, notably New Zealand, Australia and South America, but with a ...

'' *''

Acaena alpina ''Acaena alpina'' is a perennial shrub of the genus ''Acaena'' known for its hardiness and durability. ''A. alpina'' is found throughout central Chile and Argentina. It can withstand a wide range of climates, including that of the Andes, where i ...

'' *''

Acaena anserinifolia ''Acaena'' is a genus of about 60 species of mainly evergreen, creeping herbaceous perennial plants and subshrubs in the family Rosaceae, native mainly to the Southern Hemisphere, notably New Zealand, Australia and South America, but with a ...

'' *''

Acaena antarctica ''Acaena antarctica'' is a small herbaceous plant in the Rosaceae family native to Argentina, Chile and the Falkland Islands. Taxonomy and naming ''Acaena antarctica'' was first formally described in 1846 by Joseph Dalton Hooker. Kew holds s ...

'' *''

Acaena argentea ''Acaena'' is a genus of about 60 species of mainly evergreen, creeping herbaceous perennial plants and subshrubs in the family Rosaceae, native mainly to the Southern Hemisphere, notably New Zealand, Australia and South America, but with a ...

'' *''

Acaena boliviana ''Acaena'' is a genus of about 60 species of mainly evergreen, creeping herbaceous perennial plants and subshrubs in the family Rosaceae, native mainly to the Southern Hemisphere, notably New Zealand, Australia and South America, but with a ...

'' *''

Acaena buchananii ''Acaena'' is a genus of about 60 species of mainly evergreen, creeping herbaceous perennial plants and subshrubs in the family Rosaceae, native mainly to the Southern Hemisphere, notably New Zealand, Australia and South America, but with a ...

'' *''

Acaena caesiiglauca ''Acaena caesiiglauca'' (common name: glaucous pirri-pirri-bur or silver-leafed New Zealand burr) is a species of ''Acaena ''Acaena'' is a genus of about 60 species of mainly evergreen, creeping herbaceous perennial plants and subshrubs i ...

'' – glaucous pirri-pirri-bur *'' Acaena caespitosa'' *'' Acaena confertissima'' *'' Acaena cylindristachya'' *'' Acaena dumicola'' ( South Island of New Zealand) *'' Acaena echinata'' – sheep's burr *'' Acaena elongata'' *'' Acaena emittens'' ( North Island of New Zealand) *'' Acaena eupatoria'' *''

Acaena exigua ''Acaena exigua'' is an extinct species of flowering plant in the rose family known by the common name liliwai. It was endemic to Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Oce ...

'' – ''liliwai'' (

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...

) *'' Acaena fissistipula'' *'' Acaena fuscescens'' *'' Acaena glabra'' *'' Acaena hirsutula'' *'' Acaena inermis'' *'' Acaena integerrima'' *'' Acaena juvenca'' (New Zealand) *'' Acaena latebrosa'' *'' Acaena leptacantha'' *'' Acaena longiscapa'' *'' Acaena lucida'' *'' Acaena macrocephala'' *'' Acaena magellanica'' – greater burnet *'' Acaena masafuerana'' *''

'' – New Zealand-bur *'' Acaena minor'' *'' Acaena montana'' *'' Acaena myriophylla'' *''

Acaena novae-zelandiae ''Acaena novae-zelandiae'', commonly known as red bidibid, bidgee widgee, buzzy and piri-piri bur, is a small herbaceous, prostrate perennial, native to New Zealand, Australia and New Guinea, of the family Rosaceae. Description ''Acaena nov ...

'' – red bidibid (New Zealand) *'' Acaena ovalifolia'' *'' Acaena ovina'' *'' Acaena pallida'' – sand bidibid *'' Acaena patagonica'' *''

Acaena pinnatifida ''Acaena pinnatifida'', the Argentinian biddy-biddy, is a species of perennial plant. Subspecies ''Acaena pinnatifida'' is often discussed as comprising several varieties. These include: *''Acaeana pinnatifida'' var. ''californica'' which is fo ...

'' – Argentinian biddy-biddy *'' Acaena platyacantha'' *'' Acaena poeppigiana'' *'' Acaena profundeincisa'' *'' Acaena pumila'' *'' Acaena rorida'' (North Island) *'' Acaena saccaticupula'' *'' Acaena sarmentosa'' *'' Acaena sericea'' *'' Acaena splendens'' *'' Acaena stangii'' *'' Acaena stricta'' *'' Acaena subincisa'' *'' Acaena tenera'' – lesser burnet *'' Acaena tesca'' (South Island) *'' Acaena torilicarpa'' *'' Acaena trifida''

Invasive species

Some species have been introduced accidentally to other areas, attached to

sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to domesticated ...

wool Wool is the textile fibre obtained from sheep and other mammals, especially goats, rabbits, and camelids. The term may also refer to inorganic materials, such as mineral wool and glass wool, that have properties similar to animal wool. ...

, and have become invasive species. ''

'', one of the bidibids from New Zealand, is the most commonly encountered species in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...

, where it is often abundant on coastal sand dunes, crowding out native vegetation and creating an often painful nuisance with the barbed burrs. In California, '' A. pallida'', ''A. novae-zelandiae'' and '' A. anserinifolia'' are considered serious weeds."Weeds Sorted by Pest Rating"
CFDA.ca.gov

References

External links

Jepson Manual TreatmentUSDA Plants ProfileLandcare Research New Zealand
{{Taxonbar, from=Q1327017 Pantropical flora Rosaceae genera