Ageratina is a genus of about 250–290 perennial

Perennial plant

A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...

s and rounded shrub

Shrub

A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

s in the sunflower

Sunflower

Sunflower is an annual plant native to the Americas. It possesses a large inflorescence . The sunflower got its name from its huge, fiery blooms, whose shape and image is often used to depict the sun. The sunflower has a rough, hairy stem, broad, coarsely toothed, rough leaves and circular heads...

 family (Asteraceae

Asteraceae

The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...

).

These plants grow mainly in the warmer regions of the Americas

Americas

The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...

. Over 150 species are native to Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. Some flourish in the cooler areas of the eastern United States

Eastern United States

The Eastern United States, the American East, or simply the East is traditionally defined as the states east of the Mississippi River. The first two tiers of states west of the Mississippi have traditionally been considered part of the West, but can be included in the East today; usually in...

. Two Mexican species have become a pest in parts of Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 and Taiwan

Taiwan

Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

. Ageratina used to belong to the genus Eupatorium

Eupatorium

Eupatorium is a genus of flowering plants in the aster family, Asteraceae, containing from 36 to 60 species depending on the classification system. Most are herbaceous perennial plants growing to 0.5–3 m tall. A few are shrubs. The genus is native to temperate regions of the Northern Hemisphere....

, but it has been reclassified.

Description

The inflorescence

Inflorescence

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

 consists of multiple fluffy, red or pinkish-white capitula in clusters. These lack the typical ray flower

Flower

A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

s of the composites.

They have multiple, much-branched woody stems

Plant stem

A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...

. The petioles

Petiole (botany)

In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...

 are rather long. The leaves are triangular, serrate and opposite with a foul-smelling, musky scent.

Species

Ageratina adenophora Ageratina adenophora Ageratina adenophora is a species of flowering plant in the daisy family known by many common names, including eupatory, sticky snakeroot, crofton weed, and Mexican devil.- Description :... Ageratina altissima Ageratina amblyolepis Ageratina areolaris Ageratina aromatica Ageratina atrocordata Ageratina beamanii Ageratina bellidifolia Ageratina blepharilepis Ageratina brandegeana Ageratina brevipes Ageratina calaminthifolia Ageratina calophylla Ageratina campylocladia Ageratina capillipes Ageratina cardiophylla Ageratina cerifera Ageratina chazaroana Ageratina chiapensis Ageratina choricephala Ageratina collodes Ageratina conspicua Ageratina crassiramea Ageratina cremastra Ageratina cronquistii Ageratina cuencana Ageratina cuencana Ageratina cuencana is a species of flowering plant in the Asteraceae family.It is found only in Ecuador.Its natural habitats are subtropical or tropical moist montanes and subtropical or tropical high-altitude shrubland.It is threatened by habitat loss.... Ageratina cylindrica Ageratina deltoidea Ageratina dendroides Ageratina dendroides Ageratina dendroides is a species of flowering plant in the Asteraceae family.It is found only in Ecuador.Its natural habitats are subtropical or tropical moist montanes and subtropical or tropical high-altitude grassland.... Ageratina dolichobasis Ageratina enixa Ageratina espinosarum

Ageratina etlensis Ageratina flourensifolia Ageratina geminata Ageratina gentryana Ageratina glabrata Ageratina glauca Ageratina glischra Ageratina gonzalezorum Ageratina grashoffii Ageratina gypsophila Ageratina halbertiana Ageratina havanensis Ageratina havanensis Ageratina havanensis is a species of flowering shrub in the sunflower family, Asteraceae, that is native to Texas, Mexico, and the Caribbean. Unlike many other species of Ageratina, it is evergreen.... Ageratina hasegawana Ageratina helenae Ageratina henzium Ageratina herbacea Ageratina herbacea Ageratina herbacea is a species of flowering plant in the daisy family known by the common names fragrant snakeroot and Apache snakeroot. It is native to the southwestern United States and northern Mexico, where it grows in several habitat types. This is a perennial herb growing a green, fuzzy stem... Ageratina heterophylla Ageratina huahuapana Ageratina hyssopina Ageratina irrasa Ageratina isolepis Ageratina jaliscensis Ageratina jalpana Ageratina jolotepecana Ageratina josepaneroi Ageratina jucunda Ageratina kochiana Ageratina lasia Ageratina lasioneura Ageratina leiocarpa Ageratina lemmonii Ageratina leptodictyon Ageratina liebmannii Ageratina ligustrina

Ageratina luciae-brauniae Ageratina lucida Ageratina macbridei Ageratina macbridei Ageratina macbridei is a species of flowering plant in the Asteraceae family.It is found only in Peru.-References:* World Conservation Monitoring Centre 1998. . Downloaded on 20 July 2007.... Ageratina macdonaldii Ageratina macvaughii Ageratina mairetiana Ageratina malacolepis Ageratina manantlana Ageratina megacephala Ageratina miahuatlana Ageratina moorei Ageratina muelleri Ageratina neohintonorium Ageratina nesomii Ageratina oaxacana Ageratina occidentalis Ageratina occidentalis Ageratina occidentalis is a species of flowering plant in the daisy family known by the common name western snakeroot or western eupatorium. It is native to the western United States where it grows in several types of habitat. This is a rhizomatous perennial herb growing fuzzy green or purple stems... Ageratina oligocephala Ageratina oreithales Ageratina ovilla Ageratina ozolotepecana Ageratina palmeri Ageratina parayana Ageratina paupercula Ageratina pazcuarensis Ageratina pendula Ageratina pelotropha Ageratina petiolaris Ageratina photina Ageratina pichinchensis Ageratina potosina Ageratina pringlei Ageratina prunellifolia Ageratina pseudochilca Ageratina queretaroana

Ageratina ramireziorum Ageratina ramonensis Ageratina resiniflua Ageratina rhomboidea Ageratina rhypodes Ageratina rhypodes Ageratina rhypodes is a species of flowering plant in the Asteraceae family.It is found only in Ecuador.Its natural habitats are subtropical or tropical moist montanes and subtropical or tropical high-altitude grassland.It is threatened by habitat loss.... Ageratina riparia Ageratina robinsoniana Ageratina rothrockii Ageratina rubicaulis Ageratina salicifolia Ageratina saltillensis Ageratina sandersii Ageratina scordonioides Ageratina shastensis Ageratina shastensis Ageratina shastensis is a species of snakeroot which is endemic to Shasta County, California. It is known by the common names Shasta snakeroot and Shasta eupatorium.-Description:... Ageratina sodiroi Ageratina sodiroi Ageratina sodiroi is a species of flowering plant in the Asteraceae family.It is found only in Ecuador.Its natural habitats are subtropical or tropical moist montanes and subtropical or tropical high-altitude shrubland.It is threatened by habitat loss.... Ageratina sousae Ageratina stricta Ageratina sundbergii Ageratina thyrsiflora Ageratina tomentella Ageratina triangulata Ageratina triniona Ageratina venulosa Ageratina vernalis Ageratina viburnoides Ageratina viejoana Ageratina villarrealii Ageratina viscosissima Ageratina warnockii Ageratina wrightii Ageratina yecorana Ageratina zunilana

Toxicity

Milk from cows that have eaten snakeroot can cause illness

Milk sickness

Milk sickness, also known as tremetol vomiting, or in animals as trembles, is characterized by trembling, vomiting, and severe intestinal pain that affects individuals who ingest milk or other dairy products, or meat from a cow that has fed on white snakeroot, which contains the poison...

 if ingested because the milk becomes toxic. Symptoms of milk sickness include vomiting.

Medicinal Use

Ageratina pichinchensis is a traditional Mexican treatment for superficial fungal infections of the skin. These plant extracts contain encecalin which has activity to inhibit and kill the fungus. Studies have compared its effectiveness in treating toenail fungus

Onychomycosis

Onychomycosis means fungal infection of the nail. It is the most common disease of the nails and constitutes about a half of all nail abnormalities....

 with ciclopirox.