''Ageratum houstonianum'', commonly known as flossflower, bluemink, goatweed, blueweed, pussy foot or Mexican paintbrush, is a cool-season

annual plant An annual plant is a plant that completes its life cycle, from germination to the production of seeds, within one growing season, and then dies. Globally, 6% of all plant species and 15% of herbaceous plants (excluding trees and shrubs) are ...

often grown as

bedding Bedding, also called bedclothes or bed linen, is the materials laid above the mattress of a bed for hygiene, warmth, protection of the mattress, and decorative effect. Bedding is the removable and washable portion of a human sleeping environment ...

in gardens.

Description

This

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...

annual Annual may refer to: *Annual publication, periodical publications appearing regularly once per year **Yearbook **Literary annual *Annual plant *Annual report *Annual giving *Annual, Morocco, a settlement in northeastern Morocco *Annuals (band), a ...

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 Corymb is a botanical term for an inflorescence with the flowers growing in such a fashion that the outermost are borne on longer pedicels than the inner, bringing all flowers up to a common level. A corymb has a flattish top with a superficial re ...

. The ray flowers are threadlike and fluff-haired, leading to the common name. The narrow

lanceolate The following terms are used to describe leaf plant morphology, morphology in the description and taxonomy (biology), taxonomy of plants. Leaves may be simple (that is, the leaf blade or 'lamina' is undivided) or compound (that is, the leaf blade ...

bracts are pointed, denticulate only at the top and glandular hairy. The flowering period is from May to November in the northern hemisphere. The plant attracts butterflies. Bluemink1

Range

The plant is

native Native may refer to: People * '' Jus sanguinis'', nationality by blood * '' Jus soli'', nationality by location of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Nat ...

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

in Guatemala and Belize, and adjacent parts of Mexico, but has become an

invasive weed An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native species ...

in other areas. It was also naturalized in large parts of the tropics and in the

southern United States The Southern United States (sometimes Dixie, also referred to as the Southern States, the American South, the Southland, Dixieland, or simply the South) is List of regions of the United States, census regions defined by the United States Cens ...

. Its habitat is

pasture Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Types of pasture Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, c ...

s, moist forest clearings and bushes up to altitudes of . Today, it is widely used as an

ornamental plant Ornamental plants or ''garden plants'' are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars th ...

for summer borders and balcony boxes, high varieties also as

cut flower Cut flowers are flowers and flower buds (often with some stem and leaf) that have been cut from the plant bearing it. It is removed from the plant for decorative use. Cut greens are leaves with or without stems added to the cut flowers for con ...

s. 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 .

Chemistry

''Ageratum'' has evolved a unique method of protecting itself from insects: it produces a

methoprene Methoprene is a juvenile hormone (JH) analog and insect growth regulator (IGR) used widely in pest control. Classified under Insecticide Resistance Action Committee (IRAC) group 7A, methoprene is an amber-colored liquid with a faint fruity odor. ...

-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. It contains

pyrrolizidine alkaloids Pyrrolizidine alkaloids (PAs), sometimes referred to as necine bases, are a group of naturally occurring alkaloids based on the structure of pyrrolizidine. Their use dates back centuries and is intertwined with the discovery, understanding, and ...

Weed risk

''Ageratum houstonianum'' is prone to becoming a rampant environmental

weed A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...

when grown outside of its natural range. It has become an invasive weed in the United States, Australia,

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

, China, Japan, New Zealand, and the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

Varieties

*''Ageratum houstonianum'' var. ''angustatum'' B.L. Rob. *''Ageratum houstonianum'' f. ''isochroum'' *''Ageratum houstonianum'' f. ''luteum'' *''Ageratum houstonianum'' var. ''muticescens'' *''Ageratum houstonianum'' f. ''niveum'' *''Ageratum houstonianum'' f. ''normale'' *''Ageratum houstonianum'' var. ''typicum'' *''Ageratum houstonianum'' f. ''versicolor'' The

cultivars A cultivar is a kind of cultivated plant that people have selected for desired traits and which retains those traits when propagated. Methods used to propagate cultivars include division, root and stem cuttings, offsets, grafting, tissue cult ...

'Blue Danube' and 'Blue Horizon' have 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 ...

Award of Garden Merit The Award of Garden Merit (AGM) is a long-established award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. It includes the full range of cultivated p ...

References

External links

* * {{Taxonbar, from=Q280807 houstonianum Annual plants Flora of Central America Flora of Mexico Garden plants of North America Garden plants of Central America Taxa named by Philip Miller