Acaena

Taxobox
name = "Acaena"

---

image_width = 250px
image_caption = "Acaena novae-zelandiae" foliage and various fruiting stages
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Rosales
familia = Rosaceae
subfamilia = Rosoideae
tribus = Sanguisorbeae
subtribus= Sanguisorbinae
genus = "Acaena"
genus_authority = L.
subdivision_ranks = Species
subdivision = See text.

"Acaena" is a genus of about 100 species of perennial herbs and subshrubs in the Rosaceae, native 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, 4-15 cm long, and pinnate or nearly so, with 7-21 leaflets. The flowers are produced in a tight globose inflorescence 1-2 cm diameter, with no petals. The fruit is also a dense ball of many seeds; 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 "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". [Orsman, H. W. (1999). "The Dictionary of New Zealand English". Auckland: Oxford University Press.]

;Selected species

Invasive species

Some species have been introduced accidentally to other areas, attached to sheep's wool, and have become invasive species. "A. novae-zelandiae", one of the bidibids from New Zealand, is the most commonly encountered species in Great Britain, 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", from New Zealand and southeast Australia, is similarly a problem species.

External links

* [http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?6677,6678 Jepson Manual Treatment]
* [http://plants.usda.gov/java/profile?symbol=ACAEN USDA Plants Profile]
* [http://www.landcareresearch.co.nz/ Landcare Research New Zealand]

References