Ragweeds
A ragweed, Ambrosia sp.
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Subclass: Asteridae (unranked) Euasterids II Order: Asterales Family: Asteraceae Subfamily: Asteroideae Tribe: Heliantheae Subtribe: Ambrosiinae Genus: Ambrosia L., 1753
Species
Some 40, see text. Plants are living Organisms belonging to the kingdom Plantae. The flowering plants or angiosperms ( Angiospermae or Magnoliophyta) are the most widespread group Magnoliopsida is the Botanical name for a class of Flowering plants By definition the class will include the family Magnoliaceae, but its Asteridae is a Botanical name at the rank of subclass. Circumscription of the subclass has varied with the taxonomic system being In the APG II system (2003 for the classification of Flowering plants, the name asterids refers to a Clade (a Monophyletic group The Asterales are an order of Dicotyledonous Flowering plants which include the composite family Asteraceae ( Sunflowers daisies The family Asteraceae or Compositae (known as the aster, daisy, or sunflower family) is the largest family of Flowering Asteroideae is a Subfamily of the Plant family Asteraceae. It is made of several Tribes including Astereae, Calenduleae The tribe Heliantheae is the most familiar tribe of the Sunflower family ( Asteraceae) Carl Linnaeus (Latinized as Carolus Linnaeus, also known after his ennoblement as, May 23 new style (13 May old style 1707 who laid the foundations for Year 1753 ( MDCCLIII) was a Common year starting on Monday (link will display the full calendar of the Gregorian calendar (or a Common year In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank.

Ragweeds (Ambrosia), also called bitterweeds and bloodweeds, are a genus of flowering plants from the sunflower family (Asteraceae). A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic Plants are living Organisms belonging to the kingdom Plantae. In Biological classification, family ( Latin The family Asteraceae or Compositae (known as the aster, daisy, or sunflower family) is the largest family of Flowering

The scientific name of this genus is sometimes claimed to be derived from the Ancient Greek term for the perfumed nourishment of the gods, ambrosia (ἀμβροσία) which would be ironic since the genus is best known for one fact: its pollen produces severe and widespread allergies. The Ancient Greek language is the historical stage in the development of the Hellenic language family spanning the Archaic (c In ancient Greek mythology, ambrosia is sometimes the food sometimes the drink of the gods, often depicted as conferring ageless Immortality Pollen is a fine to coarse powder consisting of microgametophytes ( pollen grains) which produce the male Gametes (sperm cells of Allergy is a disorder of the Immune system often also referred to as Atopy. However, the generic name is actually cognate with the name of the divine dish, both being derived from ambrotos (άμβροτος), "immortal". Cognates in Linguistics are words that have a common origin They may occur within a language such as shirt and skirt as two English words descended from Immortality (or eternal life) is the concept of living in physical or spiritual form for an Infinite length of Time. In the case of the plants, this aptly refers to their tenaciousness, which makes it hard to rid an area of them if they occur as invasive weeds. Introduced species|Weed Invasive species is a phrase with several definitions

Ragweeds occur in temperate regions of the northern hemisphere and South America. Northern Hemisphere is the half of a Planet that is North of the Equator —the word hemisphere literally means 'half ball' South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a Ragweeds prefer dry, sunny grassy plains, sandy soils, and to grow along river banks, along roadsides, disturbed soils, vacant lots and ruderal sites. "Riverine" redirects here For the use of that term in Maritime geography, see there

There are c. 41 species worldwide. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. Many are adapted to the arid climates of the desert. In general terms the Climate of a local or region is said to be arid when it is characterized by a severe lack of available Water, to the extent of hindering A desert is a Landscape or region that receives very little precipitation. Burrobush (A. Ambrosia dumosa, the burro-weed or white bursage, is a common constituent of the creosote-bush scrub community throughout the Mojave desert of California dumosa) is one of the most arid-adapted perennials in North America. About 10 species occur in the Sonoran Desert. The Sonoran Desert (sometimes called the Gila Desert after the Gila River or the Low Desert in opposition to the higher Mojave Desert) is

Description and Ecology

Silver Burr Ragweed
Ambrosia chamissonis

Common Ragweed
Ambrosia artemisiifolia

Ragweeds are annuals, perennials, and shrubs and subshrubs (called bursages), with erect, hispid stems growing in large clumps to a height of usually 75-90 cm. Common Ragweed ( Ambrosia artemisiifolia) is the most widespread plant of the genus Ambrosia in North America. Botanically an annual plant is a Plant that usually germinates, Flowers and dies in one Year. A perennial plant or perennial ( Latin per, "through" annus, "year" is a Plant that lives for more than A shrub or Bush is a horticultural rather than strictly botanical category of Woody plant, distinguished from a Tree A subshrub ( Latin suffrutex) is a Horticultural rather than strictly botanical category of Woody Perennial plant. A stem is one of two main structural axes of a Vascular plant. The stems are basally branched. They form a slender taproot or a creeping rhizome. A Plant 's taproot is a straight tapering Root that grows vertically down In Botany, a rhizome is a horizontal stem of a Plant that is usually found underground often sending out Roots and Shoots Common Ragweed (A. Common Ragweed ( Ambrosia artemisiifolia) is the most widespread plant of the genus Ambrosia in North America. artemisifolia) is the most widespread of this genus in North America. It attains a height of about a meter. Great Ragweed (Giant Ragweed, "Horseweed"; A. Conyza ( horseweed, butterweed or fleabane) is a genus of about 50 species of Flowering plants in the family Asteraceae trifida), may grow to four meters (13 feet) or more.

The foliage is grayish to silvery green with bipinnatifid, deeply lobed leaves with winged petioles; in the case of Ambrosia coronopifolia, the leaves are simple. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis. The leaf arrangement is opposite at the base, but becomes alternate higher on the stem.

Ambrosia is a monoecious plant, i. Plant sexuality covers the wide variety of Sexual reproduction systems found across the Plant kingdom e. it produces separate male and female flower heads on the same plant. The numerous tiny male inflorescences are yellowish-green disc flowers about 3 mm in diameter. 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 They grow in a terminal spike, subtended by joined bracts. In Botany, a bract is a modified or specialized Leaf. Bracts are ordinarily associated with reproductive structures (subtending Flowers Inflorescence The whitish-green single female flowers are inconspicuously situated below the male ones, in the leaf axils. A pappus is lacking. In a composite Flower, Pappus is the part of individual disk and ray flowers that surrounds the base in the same manner as the calyx does in a non-compound ^[1]

After wind pollination, the female flowers develops into a prickly, ovoid burr with 9-18 straight spines. See also Pollination syndrome Anemophily or wind pollination is a form of Pollination whereby Pollen is distributed by Wind It contains one arrowhead-shaped seed, brown when mature, and smaller than a wheat grain. This burr gets dispersed by clinging to the fur or feathers of animals passing by.

The seeds are an important winter food for many bird species. Ragweed plants are used as food by the larvae of a number of Lepidoptera (butterflies and moths); see list of Lepidoptera that feed on ragweeds. A larva ( Latin; plural larvae) is a juvenile form of Animal with indirect development, undergoing Metamorphosis (for example Lepidoptera is an order of Insect that includes Moths and butterflies. Ragweeds ( Ambrosia spp are used as food plants by the Caterpillars ( Larvae of some Lepidoptera species including

Ragweed pollen as an allergen

Main article: Allergen

Each plant is reputed to be able to produce about a billion grains of pollen over a season, and the plant is anemophilous (wind-pollinated). An allergen is a nonparasitic Antigen capable of stimulating a Type-I hypersensitivity reaction in atopic individuals Pollen is a fine to coarse powder consisting of microgametophytes ( pollen grains) which produce the male Gametes (sperm cells of Pollination in angiosperms and Gymnosperms is the process that transfers pollen grains, which contain the male Gametes (sperm to where the female It is highly allergenic, generally considered the greatest allergen of all pollens, and the prime cause of hayfever in North America. An allergen is a nonparasitic Antigen capable of stimulating a Type-I hypersensitivity reaction in atopic individuals Hay Fever is a comic play written by Noel Coward in 1924 and first produced in 1925 with Marie Tempest as the first Judith Bliss Common Ragweed (A. Common Ragweed ( Ambrosia artemisiifolia) is the most widespread plant of the genus Ambrosia in North America. artemisiifolia) and Western Ragweed A. psilostachya are considered the most noxious to those prone to hay fever. Ragweeds bloom in the northern hemisphere from about mid-August until cooler weather arrives.

A plant usually produces pollen more copiously in wet years. When the humidity rises above 70 percent, however, the pollen tends to clump and is not so likely to become airborne. Ragweed is a plant of concern in the global warming issue, because tests have shown that higher levels of carbon dioxide will greatly increase pollen production. Global warming is the increase in the average measured temperature of the Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single On dry windy days, the pollen will travel many kilometers.

Goldenrod is frequently blamed for hayfever, but simply happens to have a showy flower that blooms about the same time. The goldenrod is a yellow Flowering plant in the Family Asteraceae. A flower, also known as a bloom or Blossom, is the reproductive structure found in Flowering plants (plants of the division Magnoliophyta, also Goldenrod is entomophilous, i. See also Pollination syndrome Entomophily is a form of pollination whereby Pollen is distributed by Insects particularly Bees e. insect pollinated. Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described Its pollen is heavy and sticky, and cannot become airborne.

Some high mountain and desert areas of North America used to be refuges for severe hay fever sufferers, who would go to such areas for relief during the pollen season, but increased human activity such as building and other disturbances of the soil, irrigation, and gardening, have encouraged ragweed to spread to these areas as well. Today, no area in the United States is ragweed pollen free, and moving can only offer a degree of relief. The United States of America —commonly referred to as the Ragweeds^[2] were accidentally introduced to Europe during World War I; they thrived and have greatly spread since the 1950s. World War I (abbreviated WWI; also known as the First World War, the Great War, and the War to End All Hungary is currently the most heavily affected country in Europe (and possibly the entire world), especially since the early 1990s, when abandonment of communist-style collective agriculture left vast fields uncultivated, which were promptly invaded by ragweed. Hungary (Magyarország 'mɔɟɔrorsaːg) officially in English the Republic of Hungary ( Magyar Köztársaság, literally Magyar (Hungarian Republic

Anecdotal claims are made of honey giving some relief for ragweed pollen allergies, which is noteworthy because honeybees very rarely visit ragweed flowers, and even then only for pollen. Honey is a sweet and Viscous fluid produced by Honey bees (and some other species and derived from the nectar of Flowers According to the Allergy is a disorder of the Immune system often also referred to as Atopy. This article refers collectively to all true honey bees for the "common" domesticated honey bee see European honey bee Honey bees However, during ragweed pollen shed, the pollen dusts every surface, and honeybees, being electrostatically charged, will accumulate some ragweed pollen. The pollen is frequently identified as a component of raw honey. Melissopalynology is the study of Honey. By extension it also includes the study of any Pollen contained in honey as well as the pollen's source

The major allergenic protein has been identified as Amb a 1, a 38 kDa nonglycosylated protein composed of two subunits. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl The unified atomic mass unit ( u) or Dalton ( Da) or sometimes universal mass unit, is an unit of Mass used to express Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl In Structural biology, a protein subunit or subunit protein is a single Protein Molecule that assembles (or " coassembles " Other allergens widespread among pollen - profilin and calcium-binding proteins - are also present. Profilin is an Actin-binding protein involved in the dynamic turnover and restructuring of the Actin Cytoskeleton. Calcium-binding proteins are Proteins that participate in calcium cell signalling pathways by binding to Ca2+ ^[3]

Control and eradication

Total eradication of ragweed is considered impossible, owing to the plant's frugality and tremendous seed-producing capability. As of 2005, there is no known safe biological control to be used against ragweed in the open. Biological control of pests in Agriculture is a method of controlling pests (including Insects Mites Weeds and plant diseases Mechanical and chemical methods are available and can be used to control its spread, although there is evidence that these are actually no more effective in the long run than leaving the weed alone. ^[4]

The act of manually uprooting ragweeds, sometimes shown in the media for public awareness purposes, promises more than it can deliver. It is ineffective, and skin contact may cause the onset of full-blown hayfever symptoms in persons with latent ragweed hyper-sensitivity. That being said, ragweed is best uprooted in late spring, before the flowering season and before a strong root system has developed.

Although the scythe and its motorized descendants have a reduced efficiency against ragweed, they remain indispensable tools, especially in populated areas and near delicate plantation, where herbicides use must be limited. For the ancient Sicilian tyrant see Scythes. A scythe (ˈsaɪð from Old English siðe. A herbicide is used to kill unwanted Plants Selective herbicides kill specific targets while leaving the desired Crop relatively unharmed Fighting ragweed with the scythe is a continuous process, because it is difficult to cut the plant right at the soil level, and the plant will regrow in two weeks (and often branch into three or four full-sized stems) if more than half an inch of the plant remains above the ground. Areas where ragweed has been reaped should be mowed down every three weeks to prevent regrowth.

It is considered important to control the spread of ragweed in large abandoned or uncultivated areas. Ragweed pollen can remain airborne for days and travel great distances, affecting people hundreds of miles away. One efficient method for large-scale ragweed extermination is chemical spraying. Because ragweed only reacts to some of the more aggressive herbicides, it is highly recommended to consult professionals when deciding on dosage and methodology, especially near urban areas. Some proven effective active ingredients include those that are glyphosate-based (Roundup, Gliphogan, Glialka), sulphosat-based (Medallon) and gluphosinat-ammonia based (Finale14SL). Glyphosate (N-(phosphonomethyl glycine is a non-selective Systemic Herbicide, absorbed through the leaves injected into the bole or applied to the stump of Roundup is the brand name of a systemic broad-spectrum Herbicide produced by the U In badly infested areas usually 2 to 6. 5 liters of herbicides are dispersed per hectare (approx. The litre or liter (see spelling differences) is a unit of Volume. Explanation The hectare is commonly used in most countries around the world especially in domains concerned with land planning and management such as Agriculture, 0. 2 to 0. 7 US gallons per acre). A gallon is a measure of Volume. It is in current use in the United States and still has limited use in many other English-speaking countries The acre is a unit of Area in a number of different systems including the imperial and U

One favored method of controlling ragweed in the past was cutting it, leaving the cuts in the field, then burning them there once the stalks have dried^[4] since standing, live ragweed won't burn. It has become less popular today because the smoke produced is seen as unacceptable pollution, as with the decline in leaf-burning and trash burning. Pollution is the introduction of contaminants into an environment that causes instability disorder harm or discomfort to the physical systems or living organisms they are in But the method has the added benefit of killing off the stems so the plant does not grow back, which (as noted above) is otherwise almost inevitable.

Species

Flatspine Burr Ragweed
Ambrosia acanthicarpa

Western Ragweed
Ambrosia psilostachya

Laceleaf Ragweed
Ambrosia bidentata

• Ambrosia acanthicarpa – Flatspine Burr Ragweed, Annual Bursage
• Ambrosia ambrosioides – Ambrosia Burr Ragweed, Canyon Ragweed, chicura
  • Ambrosia ambrosioides ssp. Ambrosia acanthicarpa is a species of Ragweed known by the common names flatspine burr ragweed, annual burrweed, and annual bur-sage Ambrosia acanthicarpa is a species of Ragweed known by the common names flatspine burr ragweed, annual burrweed, and annual bur-sage Ambrosia ambrosioides, also known as canyon ragweed or chicura is a Ragweed found in the deserts of northern Mexico and ranging septentrionale
• Ambrosia artemisiifolia – Common Ragweed, Annual Ragweed, American Wormwood, Blackweed, Carrotweed
• Ambrosia aspera
• Ambrosia bidentata – Camphor Weed, Lanceleaf Ragweed
• Ambrosia canescens – Hairy Ragweed
• Ambrosia carduacea – Baja California Ragweed
• Ambrosia chamissonis – Silver Burr Ragweed, Silver Beachweed, Silver Beach Burr
• Ambrosia cheirnathifolia – Rio Grande Ragweed
• Ambrosia chenopodiifolia – San Diego Burr Ragweed, San Diego Burrsage
• Ambrosia confertiflora – Weakleaf Burr Ragweed
• Ambrosia cordifolia – Tucson Burr Ragweed
• Ambrosia coronopifolia
• Ambrosia deltoidea – Triangle Burr Ragweed, Triangleleaf Bursage, Rabbitbush
• Ambrosia dumosa – Burrobush, Burroweed, White Bursage
• Ambrosia grayi – Woollyleaf Burr Ragweed
• Ambrosia helenae
• Ambrosia hispida – Coastal Ragweed
• Ambrosia ilicfolia – Hollyleaf Burr Ragweed, Hollyleaf Bursage
• Ambrosia intergradiens
• Ambrosia johnstoniorum
• Ambrosia linearis – Streaked Burr Ragweed
• Ambrosia maritima (the type species)
• Ambrosia palustris
• Ambrosia pannosa
• Ambrosia parvifolia
• Ambrosia peruviana – Peruvian Ragweed
• Ambrosia psilostachya – Western Ragweed, Cuman Ragweed, Perennial Ragweed
• Ambrosia pumila – Dwarf Burr Ragweed, San Diego Ambrosia
• Ambrosia sandersonii
• Ambrosia scabra
  • Ambrosia scabra var. Common Ragweed ( Ambrosia artemisiifolia) is the most widespread plant of the genus Ambrosia in North America. Ambrosia dumosa, the burro-weed or white bursage, is a common constituent of the creosote-bush scrub community throughout the Mojave desert of California In Taxonomy, a type species is the species that originally defined a genus. robusta
  • Ambrosia scabra var. tenuior
• Ambrosia tarapacana
• Ambrosia tenuifolia – Slimleaf Burr Ragweed
• Ambrosia tomentosa – Skeletonleaf Burr Ragweed
• Ambrosia trifida – Great Ragweed, Giant Ragweed, Buffalo Weed
  • Ambrosia trifida texana – Texan Great Ragweed
• Ambrosia trifolia – Greater Ragweed
• Ambrosia velutina

Ambrosia mexicana is actually the Jerusalem Oak Goosefoot (Chenopodium botrys), an entirely unrelated plant. Ambrosia trifida, variously called Buffalo Weed, Great Ragweed, Giant Ragweed, Bitterweed, Bloodweed, Horse Cane Jerusalem Oak Goosefoot ( Chenopodium botrys) also called Feathered Geranium is a Flowering plant in the Genus Chenopodium,

Footnotes

References

• Lewis, Alan J. (1973): Ragweed Control Techniques: Effect on Old-Field Plant Populations. Bulletin of the Torrey Botanical Club 100(6): 333-338. doi:10.2307/2484099 (HTML abstract, first page image)
• Payne, Willard W. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. (1963): The Morphology of the Inflorescence of Ragweeds (Ambrosia-Franseria: Compositae). Am. J. Bot. 50(9): 872-880. The American Journal of Botany ( is a peer-reviewed scientific journal which includes research papers on all aspects of plant biology doi:10.2307/2439774 (HTML abstract, first page image)
• Wopfner, Nicole; Gadermaier, Gabriele; Egger, Matthias; Asero, Riccardo; Ebner, Christof; Jahn-Schmid, Beatrice & Ferreira, Fatima (2005): The spectrum of allergens in ragweed and mugwort pollen. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. International Archives of Allergy and Immunology 138(4): 337-346. doi:10.1159/000089188 PMID 16254437 (HTML abstract)
• Everitt, J. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. H. ; Lonard, R. L. , Little, C. R. (2007). Weeds in South Texas and Northern Mexico. Lubbock: Texas Tech University Press.   ISBN 0-89672-614-2 (Book)

External links

• Brightsurf - Ragweed Research Is Nothing to Sneeze At
• UVSC Herbarium - Ambrosia