Ageratum houstonianum explained

Ageratum houstonianum, commonly known as flossflower, bluemink, goatweed, blueweed, pussy foot or Mexican paintbrush, is a cool-season annual plant[1] [2] often grown as bedding in gardens.[3]

Description

This herbaceous annual or dwarf shrub grows to high, with ovate to triangular leaves long, and blue flowerheads (sometimes white, pink, or purple). The flower heads are borne in dense corymbs. The ray flowers are threadlike and fluff-haired, leading to the common name. The narrow lanceolate bracts are pointed, denticulate only at the top and glandular hairy. The flowering period is from May to November in the northern hemisphere.[4] The plant attracts butterflies.[5]

Range

The plant is native to Central America in Guatemala and Belize, and adjacent parts of Mexico, but has become an invasive weed in other areas. It was also naturalized in large parts of the tropics and in the southern United States. Its habitat is pastures, moist forest clearings and bushes up to altitudes of .

Today, it is widely used as an ornamental plant for summer borders and balcony boxes, high varieties also as cut flowers. The species is cultivated once a year, having numerous varieties whose crowns may be dark blue, purple, pink and white. Preferring cool soils and exposure in full sun, high varieties reach stature heights up to .[6]

Chemistry

Ageratum has evolved a unique method of protecting itself from insects: it produces a methoprene-like compound which interferes with the normal function of the corpus allatum, the organ responsible for secreting juvenile hormone during insect growth and development. This chemical triggers the next molting cycle to prematurely develop adult structures, and can render most insects sterile if ingested in large enough quantities.

Toxicity

Ageratum houstonianum is toxic to grazing animals, causing liver lesions.[7] [8] It contains pyrrolizidine alkaloids.[9]

Weed risk

Ageratum houstonianum is prone to becoming a rampant environmental weed when grown outside of its natural range. It has become an invasive weed in the United States, Australia, Europe, Africa, China, Japan, New Zealand, and the Philippines.[10]

Varieties

The cultivars 'Blue Danube'[12] and 'Blue Horizon'[13] have gained the Royal Horticultural Society's Award of Garden Merit.[14]

External links

. Bailey, L. H. . Manual of Gardening (Second Edition). . 2005 . . L. H. Bailey.

Notes and References

  1. Web site: Ageratum houstonianum (Ageratum, Blue Billygoatweed, Bluemink, Floss Flower, Mexican Ageratum) . North Carolina Extension Gardener Plant Toolbox . . 2021-05-15.
  2. Web site: Ageratum houstonianum . Plant Finder . . 2021-05-15.
  3. Eckehart J. Jäger, Friedrich Ebel, Peter Hanelt, Gerd K. Müller (ed.): Rothmaler - excursion flora of Germany. Volume 5: Herbaceous ornamental and useful plants . Spektrum Akademischer Verlag, Berlin Heidelberg 2008,, p. 553 .
  4. http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Ageratum~houstonianum New South Wales Flora Online, Ageratum houstonianum
  5. Web site: Ageratum houstonianum - Plant Finder. 2021-12-20. www.missouribotanicalgarden.org.
  6. http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Ageratum~houstonianum Species profile
  7. Acamovic, T., Stewart, C.S., Pennycott, T.W.,"Poisonous Plants and Related Toxins", 2004
  8. Noa, M., Sanchez, L.M., Durand, R., "Ageratum houstonianum toxicosis in Zebu cattle", Veterinary and human toxicology, 2004, vol.46, no4, pp.193-195.
  9. Wiedenfeld H, Andrade-Cetto A., "Pyrrolizidine alkaloids from Ageratum houstonianum Mill.", Phytochemistry, 2001 Aug, pp1269-71 https://www.ncbi.nlm.nih.gov/pubmed/11454357
  10. http://www.hear.org/gcw/species/ageratum_houstonianum/ Global Compendium of Weeds, Ageratum houstonianum (Asteraceae)
  11. http://plants.jstor.org/specimen/gh00000753 JSTOR Plant Science
  12. Web site: Ageratum houstoninum 'Blue Danube' . RHS . 27 February 2020.
  13. Web site: Ageratum houstonianum 'Blue Horizon' . RHS . 27 February 2020.
  14. Web site: AGM Plants - Ornamental . November 2018 . 3 . Royal Horticultural Society . www.rhs.org . 27 February 2020.